motrixsim

Exceptions:

ActuatorOverrideDampingTypeError	Raised when the requested damping override does not match the actuator damping type
ActuatorOverrideError	Base class for actuator parameter override errors
ActuatorOverrideInvalidValueError	Raised when an actuator override value is outside the valid domain
ActuatorOverrideUnsupportedTypeError	Raised when an actuator type does not support the requested override

Classes:

Actuator	The base Actuator class provides access to common actuator properties and control.
AdhesionActuator	Adhesion actuator (MJCF <adhesion>).
Body	The Body object represents a rigid body in the scene.
Camera	The Camera object in the scene.
CameraMgr
ContactQuery
DisjointIndices(indices)
FloatingBase	The FloatingBase object represents a floating base in the scene.
GeneralActuator	General actuator (MJCF <general>).
Geom	The Geom object represents a geometry in the scene.
GeomCapsule	Capsule geometry.
GeomCuboid	Cuboid (box) geometry.
GeomCylinder	Cylinder geometry.
GeomEllipsoid	Ellipsoid geometry.
GeomHField	Height field geometry.
GeomInfinitePlane	Infinite plane geometry.
GeomMesh	Mesh geometry.
GeomPlane	Sized plane geometry.
GeomSphere	Sphere geometry.
HField	The HField object represents a height field terrain in the scene.
Joint	The Joint object represents a joint in the scene.
Keyframe	The Keyframe object represents a keyframe in the scene.
Link	The Link object represents a kinematic link in the scene.
Mocap	The Mocap object represents a motion capture body in the scene.
MotorActuator	Motor actuator (MJCF <motor>).
Options	The Options object represents the simulation options.
PositionActuator	Position actuator (MJCF <position>).
SceneData(model[, batch])	The SceneData object represents the simulation state.
SceneModel	The SceneModel object represents the entire simulation world.
Shape	The source shape type of a high-level geometry.
Site	The Site object represents a reference point or marker in the scene.
TerrainScanner(terrain, frame, offsets[, ...])	A scanner object for batched frame-relative terrain height sampling.
VelocityActuator	Velocity actuator (MJCF <velocity>).

Functions:

forward_kinematic(model, data)	Run forward kinematic only.
load_mjcf_str(mjcf)	Load a model from a string containing MJCF data.
load_model(path)	Load a model from the given file path.
step(model, data)	Advance the simulation by one step.

exception motrixsim.ActuatorOverrideDampingTypeError

基类：ActuatorOverrideError

Raised when the requested damping override does not match the actuator damping type

exception motrixsim.ActuatorOverrideError

基类：ValueError

Base class for actuator parameter override errors

exception motrixsim.ActuatorOverrideInvalidValueError

基类：ActuatorOverrideError

Raised when an actuator override value is outside the valid domain

exception motrixsim.ActuatorOverrideUnsupportedTypeError

基类：ActuatorOverrideError

Raised when an actuator type does not support the requested override

class motrixsim.Actuator

基类：object

The base Actuator class provides access to common actuator properties and control.

All actuator types share the same underlying force generation equation:

force = gain * activation + bias - stiffness * position - damping * velocity

where activation is derived from the control signal (possibly filtered by activation dynamics), and position / velocity are the current state of the actuator target (e.g., joint angle and joint velocity).

Typed subclasses provide type-specific parameter override methods:

Methods:

get_ctrl(data)	Get the control value of the actuator.
set_ctrl(data, ctrl)	Set the control value of the actuator.

Attributes:

ctrl_range	The control range of the actuator.
damping_type	The damping parameterization used by this actuator.
index	The index of the actuator in the simulation world.
name	The name of the actuator.
target_name	The name of the actuator target.
target_type	The type of the actuator target.
typ	The type of the actuator.

get_ctrl(data)

Get the control value of the actuator.

参数:

data (SceneData) -- The scene data.

返回:

The current control value of the actuator. Shape: (*data.shape, )

返回类型:

NDArray[float]

set_ctrl(data, ctrl)

Set the control value of the actuator.

参数:

• data (SceneData) -- The scene data to store the control value.

• ctrl (float | NDArray[float]) -- The control value to set. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

ctrl_range

The control range of the actuator.

Returns None if not set.

Type:

Optional[Tuple[float, float]]

damping_type

The damping parameterization used by this actuator.

DampingType.Kv means absolute damping coefficient, and DampingType.Dampratio means damping ratio relative to critical damping.

Type:

DampingType

index

The index of the actuator in the simulation world.

Type:

int

name

The name of the actuator.

Return "None" if not set.

Type:

Optional[str]

target_name

The name of the actuator target. (e.g., joint name, tendon name).

Type:

str

target_type

The type of the actuator target.

valid values are:

• "floating_base": For floating base actuators.

• "joint": For joint actuators.

• "tendon": For tendon actuators.

Type:

str

typ

The type of the actuator.

valid values are:

• "general": General actuator.

• "position": Position servo. The ctrl represents the target position

• "velocity": Velocity servo. The ctrl represents the target velocity

• "motor": The ctrl represents the torque or force

Type:

str

class motrixsim.AdhesionActuator

基类：Actuator

Adhesion actuator (MJCF <adhesion>). Generates adhesion force on contact surfaces.

No additional parameter override methods. The control value scales the adhesion force.

class motrixsim.Body

基类：object

The Body object represents a rigid body in the scene.

This class provides access to the properties and state of a rigid body in the simulation. It allows you to retrieve information about the body's name, floating base, pose, and DoF positions and velocities.

Methods:

get_dof_pos_indices([include_floatingbase])	Get the indices of the DoF positions of the body.
get_dof_vel_indices([include_floatingbase])	Get the indices of the DoF velocities of the body.
get_joint_dof_pos(data)	Get the DoF positions of all joints on the body.
get_joint_dof_vel(data)	Get the DoF velocities of all joints on the body.
get_pose(data)	Get the world pose of the body.
get_position(data)	Get the world position of the body.
get_rotation(data)	Get the world rotation of the body as a quaternion.
get_rotation_mat(data)	Get the world rotation of the body as a rotation matrix.
set_actuator_ctrls(data, ctrls)	Set the control values for all actuators on this body.
set_dof_pos(data, dof_pos[, ...])	Set the DoF positions of the body.
set_dof_vel(data, dof_vel[, ...])	Set the DoF velocities of the body.

Attributes:

actuators	The list of actuators associated with this body.
base_link	The base link of this body.
floatingbase	The floating base object.
index
is_mocap	Whether the body is a mocap (kinematic) body.
mocap	Convert this body to a mocap object if it is a mocap body.
model
name	The name of the body.
num_actuators	The number of actuators associated with this body.
num_joint_dof_pos	The number of DoF positions of all joints on the body.
num_joint_dof_vel	The number of DoF velocities of all joints on the body.
num_joints	The number of joints that belong to this body.
num_links	The number of links that belong to this body.

get_dof_pos_indices(include_floatingbase=True)

Get the indices of the DoF positions of the body.

参数:

include_floatingbase (bool) -- Whether to include the floating base DoF positions indices. If False, only the joint DoF positions indices are returned.

返回:

The DoF position indices. if include_floatingbase is true, shape =

(num_joint_dof_pos() + 6,), else shape = (num_joint_dof_pos(),).

返回类型:

NDArray[int]

get_dof_vel_indices(include_floatingbase=True)

Get the indices of the DoF velocities of the body.

参数:

include_floatingbase (bool) -- Whether to include the floating base DoF velocities indices. If False, only the joint DoF velocities indices are returned.

返回:

The DoF velocity indices. if include_floatingbase is true, shape =

(num_joint_dof_vel() + 6,), else shape = (num_joint_dof_vel(),).

返回类型:

NDArray[int]

get_joint_dof_pos(data)

Get the DoF positions of all joints on the body.

参数:

data (SceneData) -- The scene data to query.

返回:

The DoF positions. shape = (*data.shape, num_joint_dof_pos()).

返回类型:

NDArray[float]

备注

If the body has floating base, the floating base DoF positions are NOT included.

get_joint_dof_vel(data)

Get the DoF velocities of all joints on the body.

参数:

data (SceneData) -- The scene data to query.

返回:

The DoF velocities. shape = (*data.shape,:meth:

body.num_joint_dof_vel).

返回类型:

NDArray[float]

备注

If the body has floating base, the floating base DoF velocities are NOT included.

get_pose(data)

Get the world pose of the body.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 7). Each pose is a 7-element array with `[x,

返回类型:

NDArray[float]

y, z, i, j, k, w]`.

get_position(data)

Get the world position of the body.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 3).

返回类型:

NDArray[float]

get_rotation(data)

Get the world rotation of the body as a quaternion.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 4). Each rotation is a 4-element array with

返回类型:

NDArray[float]

[i, j, k, w].

get_rotation_mat(data)

Get the world rotation of the body as a rotation matrix.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 3, 3).

返回类型:

NDArray[float]

set_actuator_ctrls(data, ctrls)

Set the control values for all actuators on this body.

参数:

• data (SceneData) -- The scene data to modify.

• ctrls (NDArray[float]) -- The control values to set. Shape = (len(body.actuators),). If the data has batch dimension, ctrls must have the same shape as the data.

备注

The number of control values must match the number of actuators on the body. Use body.actuators to get the list of actuators and their count.

Example:

# For a body with 3 actuators:
body.set_actuator_ctrls(data, [1.0, 0.5, -0.3])  # Set controls for all 3 actuators

set_dof_pos(data, dof_pos, include_floatingbase=True)

Set the DoF positions of the body.

参数:

• data (SceneData) -- The scene data to modify.

• dof_pos (NDArray[float]) -- The DoF positions to set. Shape = (num_joint_dof_pos + 7,) if include_floatingbase is True, else shape = (num_joint_dof_pos,).

• include_floatingbase (bool) -- Whether the provided dof_pos includes the floating base DoF positions. If True, the first 7 elements of dof_pos are treated as the floating base DoF positions.

set_dof_vel(data, dof_vel, include_floatingbase=True)

Set the DoF velocities of the body.

参数:

• data (SceneData) -- The scene data to modify.

• dof_vel (NDArray[float]) -- The DoF velocities to set. Shape = (num_joint_dof_vel() + 6,) if include_floatingbase is True, else shape =(num_joint_dof_vel(),).

• include_floatingbase (bool) -- Whether the provided dof_vel includes the floating base DoF velocities. If True, the first 6 elements of dof_vel are treated as the floating base DoF velocities.

actuators

The list of actuators associated with this body.

Returns an empty list if the body has no actuators.

备注

Actuators are associated with a body through the joints on the body. Each actuator targets a specific joint, and this method returns all actuators that target joints belonging to this body.

Type:

List[Actuator]

base_link

The base link of this body.

Type:

Link

floatingbase

The floating base object.

Return None if not present.

备注

In mjcf, a body is free moving if it has <freejoint>

Type:

Optional[FloatingBase]

index

is_mocap

Whether the body is a mocap (kinematic) body.

Return True if the body has no joints and fixed to the world, False otherwise.

Type:

bool

mocap

Convert this body to a mocap object if it is a mocap body.

返回:

The mocap object if this body is a mocap, None otherwise.

返回类型:

Optional[PyMocap]

model

name

The name of the body.

Return None if not present.

Type:

Optional[str]

num_actuators

The number of actuators associated with this body.

Type:

int

num_joint_dof_pos

The number of DoF positions of all joints on the body.

备注

If the body has floating base, the floating base DoF positions are NOT included

Type:

int

num_joint_dof_vel

The number of DoF velocities of all joints on the body.

备注

If the body has floating base, the floating base DoF velocities are NOT included

Type:

int

num_joints

The number of joints that belong to this body.

备注

The <freejoint> is not counted as a joint in motrixsim but a floating base.

Type:

int

num_links

The number of links that belong to this body.

Type:

int

class motrixsim.Camera

基类：object

The Camera object in the scene.

Methods:

get_pose(data)	Get the world pose of the camera.
set_near_far(near, far)	Set the near and far plane of the camera.
set_render_target(target[, w, h])	Set the render target of the camera.

Attributes:

depth_only	Whether the camera is in depth-only mode.
far_plane	Get the far plane distance of the camera.
fovy	Get the vertical field of view of the camera in degrees.
index	The index of the camera in the motrixsim.SceneModel.cameras().
link	Get the link that this camera is attached to.
model	The scene model that this camera belongs to.
name	Get the name of the camera.
near_plane	Get the far plane distance of the camera.
position_track	Get or set the position track mode of the camera.
render_target	Get the render target of the camera, either "window" or "image".
rotation_track	Get or set the rotation track mode of the camera.
track_target_link	Get or set the link that the camera looks at.

get_pose(data)

Get the world pose of the camera.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 7). Each pose is represented as a 7 elements

array with [x, y, z, qx, qy, qz,qw] format.

返回类型:

NDArray[float]

set_near_far(near, far)

Set the near and far plane of the camera.

参数:

• near (float) -- The near plane distance. Must be positive.

• far (float) -- The far plane distance. Must be larger than near.

set_render_target(target, w=400, h=300)

Set the render target of the camera.

参数:

• target (str) -- The render target, either "window" or "image".

• w (int) -- The width of the image if the target is "image". ignored if the target is

• "window".

• h (int) -- The height of the image if the target is "image". ignored if the target is

• "window".

备注

This method must be called before you launch the render application.

depth_only

Whether the camera is in depth-only mode.

备注

This attribute must be set before you launch the render application.

Type:

bool

far_plane

Get the far plane distance of the camera.

Type:

float

fovy

Get the vertical field of view of the camera in degrees.

Type:

float

index

The index of the camera in the motrixsim.SceneModel.cameras().

Type:

int

link

Get the link that this camera is attached to.

备注

Returns None if the camera is not attached to any link (i.e., it's a world space camera).

Type:

Optional[Link]

model

The scene model that this camera belongs to.

Type:

SceneModel

name

Get the name of the camera.

Type:

Option[str]

near_plane

Get the far plane distance of the camera.

Type:

float

position_track

Get or set the position track mode of the camera.

Possible values are:

• "free": Free to move in all directions.

• "fixed_local": Fixed the relative position to parent in local frame.

• "fixed_world": Fixed the relative position to parent in world frame.

Type:

str

render_target

Get the render target of the camera, either "window" or "image".

Type:

str

rotation_track

Get or set the rotation track mode of the camera.

Possible values are:

• "free": Free to rotate.

• "fixed_local": Fixed the relative rotation to parent in local frame.

• "fixed_world": Fixed the relative rotation to parent in world frame.

• "look_at_link": Always look at the target link. This mode requires setting the track_target_link attribute.

Type:

str

track_target_link

Get or set the link that the camera looks at.

备注

This attribute is only valid when the rotation track mode is "look_at_link".

Type:

Optional[Link]

class motrixsim.CameraMgr

基类：object

Methods:

__getitem__(key, /)	Return self[key].
get_index(name)	Get the camera index by name.
set_system_render_target(target[, w, h])	Set the render target of the system camera.
tolist()	Convert the camera manager to a list of cameras.

Attributes:

cameras	All the cameras defined in the model.
model	The scene model that this camera manager belongs to.
system_render_target	Get the render target of the system camera, either "window" or "image".

__getitem__(key, /)

Return self[key].

get_index(name)

Get the camera index by name.

参数:

name (str) -- The name of the camera.

返回:

The index of the camera.

返回类型:

int

Panics:

If the camera name does not exist.

set_system_render_target(target, w=400, h=300)

Set the render target of the system camera.

参数:

• target (str) -- The render target, either "window" or "image".

• w (int) -- The width of the image if the target is "image". ignored if the target is

• "window".

• h (int) -- The height of the image if the target is "image". ignored if the target is

• "window".

备注

This method must be called before you launch the render application.

tolist()

Convert the camera manager to a list of cameras.

cameras

All the cameras defined in the model.

Type:

List[Camera]

model

The scene model that this camera manager belongs to.

Type:

SceneModel

system_render_target

Get the render target of the system camera, either "window" or "image".

Type:

str

class motrixsim.ContactQuery

基类：object

Methods:

is_colliding(geom_pairs)

Given a list of geometry pairs, check if they are colliding.

Attributes:

num_contacts

The number of contacts in the world.

is_colliding(geom_pairs)

Given a list of geometry pairs, check if they are colliding.

参数:

geom_pairs (NDArray[u32]) -- Pairs of geometry indices to check for collision. Shape = (N, 2) where N is the number of pairs.

返回:

Array of booleans indicating whether each pair is colliding.

返回类型:

NDArray[bool]

num_contacts

The number of contacts in the world.

Type:

int

class motrixsim.DisjointIndices(indices)

基类：object

Attributes:

size	The number of elements in the disjoint index set.

size

The number of elements in the disjoint index set. Alias to len(set).

class motrixsim.FloatingBase

基类：object

The FloatingBase object represents a floating base in the scene.

This class provides access to the properties and state of a floating base in the scene. It allows you to retrieve information about the base's name, DoF velocities and positions, and to set its world translation and rotation.

Methods:

get_dof_pos(data)	Get the DoF positions of the floating base.
get_dof_vel(data)	Get the DoF velocities of the floating base.
get_global_angular_velocity(data)	Extract the world angular velocity of the floating base from the dof velocity array.
get_global_linear_velocity(data)	Extract the world linear velocity of the floating base from the dof velocity array.
get_local_angular_velocity(data)	Extract the local angular velocity of the floating base from the dof velocity array.
get_rotation(data)	Extract the world rotation of the floating base from the dof position array.
get_translation(data)	Extract the world translation of the floating base from the dof position array.
set_global_angular_velocity(data, vel)	Set the global angular velocity of the floating base to dof velocity array directly.
set_global_linear_velocity(data, vel)	Set the global linear velocity of the floating base to dof velocity array directly.
set_local_angular_velocity(data, vel)	Set the local angular velocity of the floating base to dof velocity array directly.
set_rotation(data, quat)	Set the world rotation of the floating base.
set_translation(data, translation)	Set the world translation of the floating base.

Attributes:

dof_pos_indices	The DoF position indices of the floating base.
dof_pos_start	The DoF position address of the floating base in the motrixsim.SceneData.dof_pos().
dof_vel_indices	The DoF velocity indices of the floating base.
dof_vel_start	The DoF velocity address of the floating base in the motrixsim.SceneData.dof_vel().
index	The index of the floatingbase in the motrixsim.SceneModel.floating_bases().
model	The scene model this floating base belongs to.
name	The name of the floating base.

get_dof_pos(data)

Get the DoF positions of the floating base.

参数:

data (SceneData) -- The scene data to query.

返回:

The DoF positions with (x,y,z, i,j,k,w) format. shape = (data.shape, 7).

返回类型:

NDArray[float]

get_dof_vel(data)

Get the DoF velocities of the floating base.

参数:

data (SceneData) -- The scene data to query.

返回:

The DoF velocities with (vx,vy,vz wx,wy,wz) format. shape = (data.shape, 6).

返回类型:

NDArray[float]

get_global_angular_velocity(data)

Extract the world angular velocity of the floating base from the dof velocity array.

参数:

data (SceneData) -- The scene data to query.

返回:

The world angular velocity. shape = (data.shape, 3)

返回类型:

NDArray[float]

get_global_linear_velocity(data)

Extract the world linear velocity of the floating base from the dof velocity array.

参数:

data (SceneData) -- The scene data to query.

返回:

The world linear velocity. shape = (data.shape, 3)

返回类型:

NDArray[float]

get_local_angular_velocity(data)

Extract the local angular velocity of the floating base from the dof velocity array.

参数:

data (SceneData) -- The scene data to query.

返回:

The local angular velocity. shape = (data.shape, 3)

返回类型:

NDArray(float)

get_rotation(data)

Extract the world rotation of the floating base from the dof position array.

参数:

data (SceneData) -- The scene data.

返回:

A quaternion representing the rotation in the format [i, j, k, w].

返回类型:

NDArray[float]

get_translation(data)

Extract the world translation of the floating base from the dof position array.

参数:

data (SceneData) -- The scene data to query.

返回:

The world translation. shape = (data.shape, 3)

返回类型:

NDArray[float]

set_global_angular_velocity(data, vel)

Set the global angular velocity of the floating base to dof velocity array directly.

参数:

• data (SceneData) -- The scene data to store the velocity.

• vel (ArrayLink[float]) -- The global angular velocity to set. shape = (data.shape, 3)

备注

This method only updates the dof velocity array.

set_global_linear_velocity(data, vel)

Set the global linear velocity of the floating base to dof velocity array directly.

参数:

• data (SceneData) -- The scene data to store the velocity.

• vel (ArrayLink[float]) -- The world linear velocity to set. shape = (data.shape, 3)

备注

This method only updates the dof velocity array.

set_local_angular_velocity(data, vel)

Set the local angular velocity of the floating base to dof velocity array directly.

参数:

• data (SceneData) -- The scene data to store the velocity.

• vel (ArrayLink(float)) -- The local angular velocity, shape = (data.shape, 3).

备注

This method only updates the dof velocity array.

set_rotation(data, quat)

Set the world rotation of the floating base.

参数:

• data (SceneData) -- The scene data to store the rotation.

• quat (NDArray[float]) -- The quaternion [i, j, k, w]. shape = (data.shape, 4).

备注

This function only updates the DoF position of the floating base. The actual rotation is updated through the forward kinematic phase.

set_translation(data, translation)

Set the world translation of the floating base.

参数:

• data (SceneData) -- The scene data to store the translation.

• translation (NDArray[float]) -- The translation [x, y, z]. shape = (data.shape, 3).

备注

This function only updates the DoF position of the floating base. The actual translation of links is updated through the forward kinematic phase.

dof_pos_indices

The DoF position indices of the floating base. size = 7.

Type:

List[int]

dof_pos_start

The DoF position address of the floating base in the motrixsim.SceneData.dof_pos().

Type:

int

dof_vel_indices

The DoF velocity indices of the floating base. size = 6.

Type:

List[int]

dof_vel_start

The DoF velocity address of the floating base in the motrixsim.SceneData.dof_vel().

Type:

int

index

The index of the floatingbase in the motrixsim.SceneModel.floating_bases().

Type:

int

model

The scene model this floating base belongs to.

Type:

SceneModel

name

The name of the floating base.

Return None if not set.

Type:

Optional[str]

class motrixsim.GeneralActuator

基类：Actuator

General actuator (MJCF <general>).

MJCF parameter mapping (assumes gaintype="fixed" and biastype="affine"):

• gainprm[0] -> gain

• biasprm[0] -> bias

• -biasprm[1] -> stiffness (sign is negated because the force equation subtracts stiffness * position)

• -biasprm[2] -> damping (sign is negated because the force equation subtracts damping * velocity)

Methods:

get_bias_override(data)	Get the bias override value from the scene data.
get_damping_override(data)	Get the damping override value from the scene data.
get_gain_override(data)	Get the gain override value from the scene data.
get_stiffness_override(data)	Get the stiffness override value from the scene data.
set_bias_override(data, bias)	Override the bias value of the actuator.
set_damping_override(data, damping)	Override the damping value of the actuator.
set_gain_override(data, gain)	Override the gain value of the actuator.
set_stiffness_override(data, stiffness)	Override the stiffness value of the actuator.

get_bias_override(data)

Get the bias override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The bias value. Shape: (*data.shape,)

返回类型:

NDArray[float]

get_damping_override(data)

Get the damping override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The damping value. Shape: (*data.shape,)

返回类型:

NDArray[float]

get_gain_override(data)

Get the gain override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The gain value. Shape: (*data.shape,)

返回类型:

NDArray[float]

get_stiffness_override(data)

Get the stiffness override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The stiffness value. Shape: (*data.shape,)

返回类型:

NDArray[float]

set_bias_override(data, bias)

Override the bias value of the actuator.

参数:

• data (SceneData) -- The scene data to modify.

• bias (NDArray[float]) -- The new bias value. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

备注

Raises ValueError if the bias is NaN or infinite.

set_damping_override(data, damping)

Override the damping value of the actuator.

参数:

• data (SceneData) -- The scene data to modify.

• damping (NDArray[float]) -- The new damping value. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

备注

Raises ValueError if the damping is negative, NaN, or infinite.

set_gain_override(data, gain)

Override the gain value of the actuator.

参数:

• data (SceneData) -- The scene data to modify.

• gain (NDArray[float]) -- The new gain value. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

备注

Raises ValueError if the gain is NaN or infinite.

set_stiffness_override(data, stiffness)

Override the stiffness value of the actuator.

参数:

• data (SceneData) -- The scene data to modify.

• stiffness (NDArray[float]) -- The new stiffness value. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

备注

Raises ValueError if the stiffness is negative, NaN, or infinite.

class motrixsim.Geom

基类：object

The Geom object represents a geometry in the scene.

This class provides access to the properties and state of a geometry in the scene. It allows you to retrieve information about the geom and colliders belong to it.

Typed subclasses provide shape-specific properties:

• GeomSphere - spherical geometry with radius

• GeomCapsule - capsule geometry with radius and half_height

• GeomCylinder - cylindrical geometry with radius and half_height

• GeomCuboid - box geometry with half_extents

• GeomEllipsoid - ellipsoidal geometry with half_extents

• GeomPlane - sized plane geometry

• GeomMesh - mesh geometry with mesh_name and mesh_scale

• GeomHField - height field geometry with hfield

• GeomInfinitePlane - infinite plane geometry

Methods:

get_angular_velocity(data)	Get the world angular velocity of the geom.
get_friction_override(data)	Get the friction override value from the scene data.
get_linear_velocity(data)	Get the world linear velocity of the geom.
get_pose(data)	Get the world pose of the geom.
set_friction_override(data, friction)	Override the friction value of the geom.

Attributes:

collision_affinity	The collision affinity of the geom.
collision_group	The collision group of the geom.
gap	The contact gap of the geom.
hfield	The height field associated with this geom.
index	The index of the geom in the motrixsim.SceneModel.geoms().
link	The parent link this geometry is attached to.
local_pose	The local pose of the geom relative to its parent link or world.
margin	The contact margin of the geom.
model	The scene model that this geom belongs to.
name	The name of the geom.
shape	The shape type of the geom.
size	The size parameters of the geom.

get_angular_velocity(data)

Get the world angular velocity of the geom.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 3). The last axis is the angular velocity with

[wx, wy, wz] format.

返回类型:

NDArray[float]

get_friction_override(data)

Get the friction override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The friction override value. shape = (*data.shape, 3).

The last axis is [slide, spin, roll].

返回类型:

NDArray[float]

get_linear_velocity(data)

Get the world linear velocity of the geom.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 3). The last axis is the linear velocity with

[vx, vy, vz] format.

返回类型:

NDArray[float]

get_pose(data)

Get the world pose of the geom.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 7). Each pose is represented as a 7 elements

with [x, y, z, i, j, k, w] format.

返回类型:

NDArray[float]

set_friction_override(data, friction)

Override the friction value of the geom.

参数:

• data (SceneData) -- The scene data to modify.

• friction (NDArray[float]) -- The new friction values [slide, spin, roll]. - Shape (3,): Single value applied to all batches - Shape (*data.shape, 3): Per-batch values

备注

If any friction component is negative, NaN, or infinite, the override will be ignored.

collision_affinity

The collision affinity of the geom.

返回:

The collision affinity mask.

返回类型:

int

备注

The collision affinity (also called collide_with) is a bitmask that specifies which collision groups this geom can collide with. Two geoms will collide if (geom1.collision_group & geom2.collision_affinity) != 0 or (geom1.collision_affinity & geom2.collision_group) != 0.

collision_group

The collision group of the geom.

返回:

The collision group identifier.

返回类型:

int

备注

The collision group is used to filter which geometries can collide with each other. Two geoms will collide if (geom1.collision_group & geom2.collision_affinity) != 0 or (geom1.collision_affinity & geom2.collision_group) != 0.

gap

The contact gap of the geom.

返回:

The distance band that determines which contacts generate solver constraints.

返回类型:

float

备注

The gap controls the distance threshold for generating solver constraints. Contacts within this distance will generate constraints in the physics solver. This can be tuned to balance stability and performance.

hfield

The height field associated with this geom.

返回:

The HField object if this geom is a height field

geometry, otherwise None.

返回类型:

Optional[HField]

备注

This is a convenience accessor on the base Geom class so that code iterating over model.geoms can check g.hfield is not None without first testing the concrete subclass type. The same property is also available on GeomHField.

index

The index of the geom in the motrixsim.SceneModel.geoms().

Type:

int

link

The parent link this geometry is attached to. None if it is a world geometry.

Type:

Link

local_pose

The local pose of the geom relative to its parent link or world.

返回:

The local pose as a numpy array of shape (7,)

with [x, y, z, i, j, k, w] format where the first 3 elements are translation and the last 4 are quaternion rotation.

返回类型:

NDArray[float]

备注

The local pose represents the position and orientation of the geom in its parent frame. If the geom is attached to a link, this is relative to that link's frame. If the geom is a world geom (no parent link), this is in world coordinates.

margin

The contact margin of the geom.

返回:

The distance threshold for detecting contacts.

返回类型:

float

备注

The margin is used to control when contact constraints are generated. A larger margin will detect contacts earlier, potentially improving stability but may also increase computational cost.

model

The scene model that this geom belongs to.

Type:

SceneModel

name

The name of the geom. Must be unique within the scene.

返回:

The name of the geom, or "None" if not set.

返回类型:

Optional[str]

shape

The shape type of the geom.

返回:

The source shape type of the geom.

返回类型:

Shape

备注

The high-level shape type determines the source geometric representation of the geom. Possible values include: Sphere, Cylinder, Capsule, Cuboid, InfinitePlane, HField, Mesh, and Plane. Each shape type has different parameters and may lower to different low-level runtime collider shapes.

size

The size parameters of the geom.

返回:

The size parameters as a numpy array of shape (3,)

with [s0, s1, s2].

返回类型:

NDArray[float]

备注

The size represents half-size parameters for different shape types:

• Sphere: [radius, 0.0, 0.0] - spherical radius

• Capsule: [radius, half_height, 0.0] - radius and half-height

• Cylinder: [radius, half_height, 0.0] - radius and half-height

• Cuboid: [half_x, half_y, half_z] - half-extents in each axis

• Plane: [half_x, half_y, 0.0] - half-extents in x and y directions

• Mesh/HField/InfinitePlane: [0.0, 0.0, 0.0] - size is ignored for these types

When a primitive shape references a mesh file, the size is automatically computed from the mesh geometry and the geom size parameters are ignored.

class motrixsim.GeomCapsule

基类：Geom

Capsule geometry.

A capsule shape defined by a radius and half-height. The total height of the capsule is 2 * half_height + 2 * radius.

Methods:

get_size_override(data)	Get the effective size override for this capsule.
set_size_override(data, size)	Override the size of this capsule.

Attributes:

half_height	The half-height of the cylindrical part of the capsule.
radius	The radius of the capsule.

get_size_override(data)

Get the effective size override for this capsule.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape (*data.shape, 2). The effective [radius, half_height].

返回类型:

NDArray[float]

set_size_override(data, size)

Override the size of this capsule.

参数:

• data (SceneData) -- The scene data to modify.

• size (NDArray[float]) -- The new size [radius, half_height]. - Shape (2,): Single value applied to all batches. - Shape (*data.shape, 2): Per-batch values.

备注

If any component is non-positive, NaN, or infinite, the override is silently ignored.

half_height

The half-height of the cylindrical part of the capsule.

返回:

The half-height of the capsule cylinder.

返回类型:

float

radius

The radius of the capsule.

返回:

The capsule radius.

返回类型:

float

class motrixsim.GeomCuboid

基类：Geom

Cuboid (box) geometry.

A box shape defined by half-extents in each axis direction.

Methods:

get_size_override(data)	Get the effective size override for this cuboid.
set_size_override(data, size)	Override the size of this cuboid.

Attributes:

half_extents

The half-extents of the cuboid.

get_size_override(data)

Get the effective size override for this cuboid.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape (*data.shape, 3). The effective

[half_x, half_y, half_z].

返回类型:

NDArray[float]

set_size_override(data, size)

Override the size of this cuboid.

参数:

• data (SceneData) -- The scene data to modify.

• size (NDArray[float]) -- The new half-extents [half_x, half_y, half_z]. - Shape (3,): Single value applied to all batches. - Shape (*data.shape, 3): Per-batch values.

备注

If any component is non-positive, NaN, or infinite, the override is silently ignored.

half_extents

The half-extents of the cuboid.

返回:

A numpy array of shape (3,) with [half_x, half_y, half_z].

返回类型:

NDArray[float]

class motrixsim.GeomCylinder

基类：Geom

Cylinder geometry.

A cylindrical shape defined by a radius and half-height.

Methods:

get_size_override(data)	Get the effective size override for this cylinder.
set_size_override(data, size)	Override the size of this cylinder.

Attributes:

half_height	The half-height of the cylinder.
radius	The radius of the cylinder.

get_size_override(data)

Get the effective size override for this cylinder.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape (*data.shape, 2). The effective [radius, half_height].

返回类型:

NDArray[float]

set_size_override(data, size)

Override the size of this cylinder.

参数:

• data (SceneData) -- The scene data to modify.

• size (NDArray[float]) -- The new size [radius, half_height]. - Shape (2,): Single value applied to all batches. - Shape (*data.shape, 2): Per-batch values.

备注

If any component is non-positive, NaN, or infinite, the override is silently ignored.

half_height

The half-height of the cylinder.

返回:

The cylinder half-height.

返回类型:

float

radius

The radius of the cylinder.

返回:

The cylinder radius.

返回类型:

float

class motrixsim.GeomEllipsoid

基类：Geom

Ellipsoid geometry.

An ellipsoidal shape defined by semi-axis lengths in each direction.

Methods:

get_size_override(data)	Get the effective size override for this ellipsoid.
set_size_override(data, size)	Override the size of this ellipsoid.

Attributes:

half_extents

The half-extents (semi-axis lengths) of the ellipsoid.

get_size_override(data)

Get the effective size override for this ellipsoid.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape (*data.shape, 3). The effective semi-axis lengths

[semi_x, semi_y, semi_z].

返回类型:

NDArray[float]

set_size_override(data, size)

Override the size of this ellipsoid.

参数:

• data (SceneData) -- The scene data to modify.

• size (NDArray[float]) -- The new semi-axis lengths [semi_x, semi_y, semi_z]. - Shape (3,): Single value applied to all batches. - Shape (*data.shape, 3): Per-batch values.

备注

If any component is non-positive, NaN, or infinite, the override is silently ignored.

half_extents

The half-extents (semi-axis lengths) of the ellipsoid.

返回:

A numpy array of shape (3,) with [semi_x, semi_y, semi_z].

返回类型:

NDArray[float]

class motrixsim.GeomHField

基类：Geom

Height field geometry.

A geometry defined by a height field asset, used for terrain and elevation data.

Methods:

sample_height(data, xy[, out])

Sample the terrain surface height at world-space XY coordinates.

Attributes:

hfield

The height field associated with this geom.

sample_height(data, xy, out=None)

Sample the terrain surface height at world-space XY coordinates.

Transforms the given world XY points into the height field's local frame, performs bilinear interpolation on the grid, and returns the world-space Z height for each query point.

参数:

• data (SceneData) -- The scene data (provides current geom world pose).

• xy (NDArray[float]) -- World-space XY coordinates. - Shape (N, 2): N query points shared across all batches. - Shape (*data.shape, N, 2): per-batch query points.

• out (Optional[NDArray[float]]) -- Pre-allocated output array of shape (*data.shape, N). When provided the result is written into this array and returned directly, avoiding an internal allocation.

返回:

World-space surface heights.

Shape (*data.shape, N).

返回类型:

NDArray[float]

备注

Points that fall outside the height field boundary are clamped to the nearest edge cell.

hfield

The height field associated with this geom.

返回:

The HField object if this geom has an associated

height field, otherwise None.

返回类型:

Optional[HField]

class motrixsim.GeomInfinitePlane

基类：Geom

Infinite plane geometry.

An unbounded plane, typically used as a ground surface.

class motrixsim.GeomMesh

基类：Geom

Mesh geometry.

A geometry defined by a triangle mesh asset. The mesh can optionally be scaled.

Attributes:

mesh_name	The name of the referenced mesh asset.
mesh_scale	The scale applied to the mesh.

mesh_name

The name of the referenced mesh asset.

返回:

The mesh asset name, or None if not set.

返回类型:

Optional[str]

mesh_scale

The scale applied to the mesh.

返回:

A numpy array of shape (3,) with [sx, sy, sz],

or None if no scaling is applied.

返回类型:

Optional[NDArray[float]]

class motrixsim.GeomPlane

基类：Geom

Sized plane geometry.

A finite rectangular plane defined by half-extents in x and y directions.

class motrixsim.GeomSphere

基类：Geom

Sphere geometry.

A spherical shape defined by a single radius parameter.

Methods:

get_size_override(data)	Get the effective size override for this sphere.
set_size_override(data, size)	Override the size of this sphere.

Attributes:

radius

The radius of the sphere.

get_size_override(data)

Get the effective size override for this sphere.

Returns the overridden radius if a size override has been set, otherwise returns the model's original radius.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape (*data.shape, 1). The effective [radius].

返回类型:

NDArray[float]

set_size_override(data, size)

Override the size of this sphere.

参数:

• data (SceneData) -- The scene data to modify.

• size (NDArray[float]) -- The new size [radius]. - Shape (1,): Single value applied to all batches. - Shape (*data.shape, 1): Per-batch values.

备注

If the radius is non-positive, NaN, or infinite, the override is silently ignored.

radius

The radius of the sphere.

返回:

The sphere radius.

返回类型:

float

class motrixsim.HField

基类：object

The HField object represents a height field terrain in the scene.

This class provides access to height field (terrain) data used for ground interactions, terrain following, and surface-based physics. Height fields provide an efficient way to represent large terrain surfaces with elevation data.

Methods:

get(row, col)

Get the height value at the specified row and column.

Attributes:

bound	Get the bounding box of the height field in local space.
height_matrix	Get the height matrix data as a numpy array.
index	The index of the hfield in the scene.
model	The scene model that this hfield belongs to.
name	The name of the hfield.
ncol	The number of columns in the height field grid.
nrow	The number of rows in the height field grid.

get(row, col)

Get the height value at the specified row and column.

参数:

• row (int) -- The row index (0-based).

• col (int) -- The column index (0-based).

返回:

The height value at the specified grid cell.

返回类型:

float

bound

Get the bounding box of the height field in local space.

返回:

A 1D numpy array of shape (6,) representing the bounding box

in the format [-extent_x, -extent_y, 0, extent_x, extent_y, size_z].

返回类型:

NDArray[float]

height_matrix

Get the height matrix data as a numpy array.

备注

The returned array is a copy of the internal data. Modifying it will not affect the hfield.

返回:

A 2D numpy array of shape (nrow, ncol) containing the height values. Row 0 is the -Y side, matching MuJoCo's compiled hfield data order.

返回类型:

NDArray[float]

index

The index of the hfield in the scene.

Type:

int

model

The scene model that this hfield belongs to.

Type:

SceneModel

name

The name of the hfield. Must be unique within the scene.

返回:

The name of the hfield, or "None" if not set.

返回类型:

Optional[str]

ncol

The number of columns in the height field grid.

Type:

int

nrow

The number of rows in the height field grid.

Type:

int

class motrixsim.Joint

基类：object

The Joint object represents a joint in the scene.

This class provides access to the properties and state of a joint in the scene. It allows you to retrieve information about the joint's name, link index, number of DoF velocities and positions, and DoF velocity and position addresses.

Methods:

get_armature_override(data)	Get the armature override value from the scene data.
get_dof_pos(data)	Get the DoF positions of the joint.
get_dof_vel(data)	Get the DoF velocities of the joint.
get_frictionloss_override(data)	Get the friction loss override value from the scene data.
set_armature_override(data, armature)	Override the armature value of the joint.
set_dof_pos(data, position)	Set the DoF positions of the joint.
set_dof_vel(data, velocity)	Set the DoF velocities of the joint.
set_frictionloss_override(data, frictionloss)	Override the friction loss value of the joint.

Attributes:

armature	The model armature value of the joint.
axis	The motion axis of the joint.
dof_pos_index	The position DoF address of the joint.
dof_vel_index	The velocity DoF address of the joint.
frictionloss	The model friction loss value of the joint.
index	The index of the joint in the motrixsim.SceneModel.joints().
link	The link this joint is attached to.
link_index	The index of the link this joint is attached to.
model	The scene model this joint belongs to.
name	The name of the joint.
num_dof_pos	The number of position DoFs of the joint.
num_dof_vel	The number of velocity DoFs of the joint.
range	The range limits of the joint.

get_armature_override(data)

Get the armature override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The armature override value. Shape: (*data.shape,)

返回类型:

NDArray[float]

get_dof_pos(data)

Get the DoF positions of the joint.

参数:

data (SceneData) -- The scene data to query.

返回:

The DoF positions. shape = (data.shape, num_dof_pos())

返回类型:

NDArray[float]

get_dof_vel(data)

Get the DoF velocities of the joint.

参数:

data (SceneData) -- The scene data to query.

返回:

The DoF velocities. shape = (data.shape, num_dof_vel())

返回类型:

NDArray[float]

get_frictionloss_override(data)

Get the friction loss override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The friction loss override value. Shape: (*data.shape,)

返回类型:

NDArray[float]

set_armature_override(data, armature)

Override the armature value of the joint.

参数:

• data (SceneData) -- The scene data to modify.

• armature (NDArray[float]) -- The new armature value. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

备注

If the armature is negative, NaN, or infinite, the override will be ignored.

set_dof_pos(data, position)

Set the DoF positions of the joint.

参数:

• data (SceneData) -- The scene data to store the new positions.

• position (NDArray[float]) -- The new DoF positions. shape = (data.shape, num_dof_pos())

set_dof_vel(data, velocity)

Set the DoF velocities of the joint.

参数:

• data (SceneData) -- The scene data to store the new velocities.

• velocity (NDArray[float]) -- The new DoF velocities. shape = (data.shape, num_dof_vel())

set_frictionloss_override(data, frictionloss)

Override the friction loss value of the joint.

参数:

• data (SceneData) -- The scene data to modify.

• frictionloss (NDArray[float]) -- The new friction loss value. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

备注

If the value is negative, NaN, or infinite, the override will be ignored.

armature

The model armature value of the joint.

Type:

float

axis

The motion axis of the joint.

Returns a 3-element array representing the motion axis of the joint in the successor body coordinate frame. This is primarily used for hinge and slide joints.

备注

The axis is normalized automatically when the joint is created. For spherical joints, the axis concept doesn't apply in the same way as they have full rotational freedom.

Type:

NDArray[float]

dof_pos_index

The position DoF address of the joint.

Return the starting index of the position DoFs.

Type:

int

dof_vel_index

The velocity DoF address of the joint.

Return the starting index of the velocity DoFs.

Type:

int

frictionloss

The model friction loss value of the joint.

Type:

float

index

The index of the joint in the motrixsim.SceneModel.joints().

Type:

int

link

The link this joint is attached to.

Type:

Link

link_index

The index of the link this joint is attached to.

Type:

int

model

The scene model this joint belongs to.

Type:

SceneModel

name

The name of the joint.

Return the name of the joint, or None if not set.

Type:

Optional[str]

num_dof_pos

The number of position DoFs of the joint.

Type:

int

num_dof_vel

The number of velocity DoFs of the joint.

Type:

int

range

The range limits of the joint.

Returns a 2-element array containing the lower and upper bounds of the joint range. Array format: [lower_bound, upper_bound] If the joint has no limits, returns [f32::NEG_INFINITY, f32::INFINITY].

Example:

joint.range
# array([[-1.57,  1.57]])  # Hinge joint with ±π/2 limits

Type:

NDArray[float]

class motrixsim.Keyframe

基类：object

The Keyframe object represents a keyframe in the scene.

This class provides access to the properties of a keyframe, including its name, simulation time, joint positions, velocities, and control values.

Methods:

apply(data)

Apply the keyframe to scene data.

Attributes:

ctrl	The actuator control values of the keyframe.
dof_pos	The dof positions of the keyframe.
dof_vel	The joint velocities of the keyframe.
index	The index of the keyframe in the keyframe list.
model	The scene model this keyframe belongs to.
name	The name of the keyframe, or None if not set.
time	The simulation time of the keyframe, or None if not set.

apply(data)

Apply the keyframe to scene data.

参数:

data (SceneData) -- Scene data to apply the keyframe to.

备注

This method does NOT automatically call forward_kinematic. Users should call model.forward_kinematic(data) after applying the keyframe if they need to update the scene transforms (e.g., for visualization or getting correct link poses).

Example:

model = motrixsim.load_model("scene.xml")
data = motrixsim.SceneData(model)
# Apply first keyframe
model.keyframes[0].apply(data)
model.forward_kinematic(data)

ctrl

The actuator control values of the keyframe.

Returns a numpy array with shape (num_actuators,) containing the actuator control values for all actuators in the scene.

Type:

NDArray[float]

dof_pos

The dof positions of the keyframe.

Returns a numpy array with shape (num_dof_pos,) containing the dof positions for all degrees of freedom in the scene.

Type:

NDArray[float]

dof_vel

The joint velocities of the keyframe.

Returns a numpy array with shape (num_dof_vel,) containing the joint velocities for all degrees of freedom in the scene.

Type:

NDArray[float]

index

The index of the keyframe in the keyframe list.

Type:

int

model

The scene model this keyframe belongs to.

Type:

SceneModel

name

The name of the keyframe, or None if not set.

Type:

Optional[str]

time

The simulation time of the keyframe, or None if not set.

Type:

float

class motrixsim.Link

基类：object

The Link object represents a kinematic link in the scene.

This class provides access to the properties and state of a kinematic link in the scene. It allows you to retrieve information about the link's name, index, joint indices, number of joints, and the joints associated with the link.

Methods:

add_external_force(data, force[, point, local])	Add an external force to the link.
add_external_torque(data, torque[, local])	Add an external torque to the link.
get_angular_velocity(data)	Get the world angular velocity of the link.
get_center_of_mass_override(data)	Get the center of mass override of the link in the link local frame.
get_joint(index)	Get the joint at the specified index if the link has multiple joints.
get_linear_velocity(data)	Get the world linear velocity of the link.
get_mass_override(data)	Get the overrided mass of the link in the scene data.
get_pose(data)	Get the world pose of the link.
get_position(data)	Get the world position of the link.
get_rotation(data)	Get the world rotation of the link as a quaternion (i, j, k, w).
get_rotation_mat(data)	Get the world rotation matrix of the link.
joints()	The joints associated with this link.
set_center_of_mass_override(data, center_of_mass)	Override the center of mass of the link.
set_mass_override(data, mass)	Override the mass of the link.

Attributes:

center_of_mass	Get the center of mass of the link in the link local frame.
geoms	The geometries directly attached to this link.
index	The index of the link in the motrixsim.SceneModel.links().
joint_indices	The joint indices of this link in the motrixsim.SceneModel.joints().
mass	Get the mass of the link in the model.
model	The scene model that this link belongs to.
name	The name of the link.
num_joints	The number of joints associated with this link.

add_external_force(data, force, point=None, local=True)

Add an external force to the link.

参数:

• data (SceneData) -- The scene data to modify.

• force (NDArray[float]) -- The force vector. - Shape: (*data.shape, 3): Per-batch force vectors

• point (NDArray[float], optional) -- Application point. - Shape: (*data.shape, 3): Per-batch points

• local (bool) -- Whether the force and point are in local coordinates. Default: True.

备注

The force is applied at the specified point in link coordinates. If point is None, force is applied at the link's center of mass. Forces applied to mocap-type links will be ignored.

add_external_torque(data, torque, local=True)

Add an external torque to the link.

参数:

• data (SceneData) -- The scene data to modify.

• torque (NDArray[float]) -- The torque vector. - Shape: (*data.shape, 3): Per-batch torque vectors

• local (bool) -- Whether the torque is in local coordinates. Default: True.

备注

Torques applied to mocap-type links will be ignored.

get_angular_velocity(data)

Get the world angular velocity of the link.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 3). The last axis is the angular velocity with

[wx, wy, wz] format.

返回类型:

NDArray[float]

get_center_of_mass_override(data)

Get the center of mass override of the link in the link local frame.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 3). The center of mass override value.

返回类型:

NDArray[float]

get_joint(index)

Get the joint at the specified index if the link has multiple joints.

参数:

index (int) -- The local index of the joint.

返回:

The joint object, or "None" if not found.

返回类型:

Optional[Joint]

get_linear_velocity(data)

Get the world linear velocity of the link.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 3). The last axis is the linear velocity with

[vx, vy, vz] format.

返回类型:

NDArray[float]

get_mass_override(data)

Get the overrided mass of the link in the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

shape = (1,). The mass override value.

返回类型:

NDArray[float]

get_pose(data)

Get the world pose of the link.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 7). Each pose is represented as a 7 elements

with [x, y, z, i, j, k, w] format.

返回类型:

NDArray[float]

get_position(data)

Get the world position of the link.

参数:

data (SceneData) -- The scene data to query.

返回:

Shape: (*data.shape, 3).

返回类型:

NDArray[float]

get_rotation(data)

Get the world rotation of the link as a quaternion (i, j, k, w).

参数:

data (SceneData) -- The scene data to query.

返回:

A numpy array with shape (*data.shape, 4).

返回类型:

NDArray[float]

get_rotation_mat(data)

Get the world rotation matrix of the link.

参数:

data (SceneData) -- The scene data to query.

返回:

A numpy array with shape (*data.shape, 3, 3).

返回类型:

NDArray[float]

joints()

The joints associated with this link.

返回:

A list of joint objects.

返回类型:

List[Joint]

set_center_of_mass_override(data, center_of_mass)

Override the center of mass of the link.

参数:

• data (SceneData) -- The scene data to modify.

• center_of_mass (NDArray[float]) -- The new center of mass. - Shape (3,): Single center of mass value applied to all batches - Shape: (*data.shape, 3): Per-batch center of mass vectors

备注

If the center_of_mass components are not finite (NaN or infinity), or the link is mocap type, or the link is fixed to world, the override will be ignored.

set_mass_override(data, mass)

Override the mass of the link.

参数:

• data (SceneData) -- The scene data to modify.

• mass (NDArray[float]) -- The new mass. - Shape (): Single mass value applied to all batches - Shape: (*data.shape,): Per-batch mass values

备注

If the mass is non-positive or the link is mocap type, or the link is fixed to world, the override will be ignored.

center_of_mass

Get the center of mass of the link in the link local frame.

返回:

shape = (3,). The center of mass position

返回类型:

NDArray[float]

geoms

The geometries directly attached to this link.

返回:

A list of geometry objects whose parent link is this link.

返回类型:

List[Geom]

index

The index of the link in the motrixsim.SceneModel.links().

Type:

int

joint_indices

The joint indices of this link in the motrixsim.SceneModel.joints().

返回:

The size of the list must be equal to num_joints()

返回类型:

List[int]

mass

Get the mass of the link in the model.

返回:

The mass of the link.

返回类型:

Real

model

The scene model that this link belongs to.

Type:

SceneModel

name

The name of the link. Must be unique within the scene.

返回:

The name of the link, or "None" if not set.

返回类型:

Optional[str]

num_joints

The number of joints associated with this link.

返回:

number of joints associated with this link.

返回类型:

int

class motrixsim.Mocap

基类：object

The Mocap object represents a motion capture body in the scene. it can will participate in the collision and apply force to other bodies, but will not be affected by the physics simulation.

Methods:

set_pose(data, pose)

Set the pose of the mocap.

Attributes:

body	The body associated with this mocap.
model	The scene model this mocap belongs to.

set_pose(data, pose)

Set the pose of the mocap.

参数:

• data (SceneData) -- The scene data to store the pose.

• pose (NDArray[float]) -- The pose to set, as a 7-element array (x, y, z, qx, qy, qz, qw). shape = (data.shape,7)

body

The body associated with this mocap.

Type:

Body

model

The scene model this mocap belongs to.

Type:

SceneModel

class motrixsim.MotorActuator

基类：Actuator

Motor actuator (MJCF <motor>). Direct torque/force control with fixed gain = 1.0.

No additional parameter override methods. The control value is applied directly as force.

class motrixsim.Options

基类：object

The Options object represents the simulation options.

This class is used to configure the simulation options. You can access it through model.options.

Attributes:

disable_contacts	Is all contact constraints disabled in the simulation?
disable_gravity	Is the gravity disabled in the simulation?
gravity	The gravity vector applied to the simulation.
max_iterations	The maximum number of iterations for the solver.
solver_tolerance	The tolerance for the solver.
timestep	The delta time for each simulation step.

disable_contacts

Is all contact constraints disabled in the simulation?

Type:

bool

disable_gravity

Is the gravity disabled in the simulation?

Type:

bool

gravity

The gravity vector applied to the simulation.

A numpy array of shape (3,) or a list of three floats representing the gravity vector.

Type:

NDArray[float]

max_iterations

The maximum number of iterations for the solver.

抛出:

ValueError -- The set max iterations is zero.

Type:

int

solver_tolerance

The tolerance for the solver.

抛出:

ValueError -- The set tolerance is not positive.

Type:

float

timestep

The delta time for each simulation step.

抛出:

ValueError -- The set timestep is not positive.

Type:

float

class motrixsim.PositionActuator

基类：Actuator

Position actuator (MJCF <position>).

MJCF parameter mapping:

• kp -> kp (writes both gain and stiffness internally)

• kv -> kd (writes damping internally, defaults to 0)

Methods:

get_dampratio_override(data)	Get the dampratio override value from the scene data.
get_kd_override(data)	Get the kd override value from the scene data.
get_kp_override(data)	Get the kp override value from the scene data.
set_damping_override(data, damping)	Override the damping value for a position actuator.
set_kp_override(data, kp)	Override the kp value for a position actuator.

get_dampratio_override(data)

Get the dampratio override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The dampratio value. Shape: (*data.shape,).

Returns None when this actuator stores DampingType.Kv in the model.

返回类型:

Optional[NDArray[float]]

get_kd_override(data)

Get the kd override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The kd value. Shape: (*data.shape,).

Returns None when this actuator stores DampingType.Dampratio in the model.

返回类型:

Optional[NDArray[float]]

get_kp_override(data)

Get the kp override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The kp value. Shape: (*data.shape,)

返回类型:

NDArray[float]

set_damping_override(data, damping)

Override the damping value for a position actuator.

The meaning of the damping value depends on the actuator's damping_type:

• DampingType.Kv: The value is the absolute damping coefficient (kv).

• DampingType.Dampratio: The value is the damping ratio relative to critical damping.

参数:

• data (SceneData) -- The scene data to modify.

• damping (NDArray[float]) -- The new damping value. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

备注

if the value is negative, NaN, infinite, or the actuator type does not support independent damping overrides, the override will be ignored.

set_kp_override(data, kp)

Override the kp value for a position actuator. Writes both gain and stiffness.

参数:

• data (SceneData) -- The scene data to modify.

• kp (NDArray[float]) -- The new kp value. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

备注

if the value is negative, NaN, infinite, or the actuator is not a position actuator, the override will be ignored.

class motrixsim.SceneData(model, batch=Ellipsis)

基类：object

The SceneData object represents the simulation state.

This class provides access to the dynamic state of the simulation, including joint positions, velocities, and other runtime data. Users can query or modify the simulation state, reset the scene to its initial state, and access low-level simulation data for advanced use cases. The state can be accessed via properties such as qpos, qvel, and via methods like reset(). For advanced control, the low property exposes the low-level data object.

Methods:

__getitem__(key, /)	Return self[key].
get(index)	Get sub-data by index.
reset(model)	Reset the scene data with the given model.
set_dof_pos(dof_pos, model)	Set the dof position for the whole world data.
set_dof_vel(dof_vel)	Set the dof velocity for the whole world data.

Attributes:

actuator_ctrls	The all the actuator control values.
dof_pos	The dof position array of the world.
dof_vel	The dof velocity array of the world.
low	The low-level data object for advanced simulation control.
ndim	The number of dimensions of the data.
shape	The shape of the data.

__getitem__(key, /)

Return self[key].

get(index)

Get sub-data by index. Alias to __getitem__

参数:

index (int | ndarray[bool] | DisjointIndices) -- The index to select. Following types are

supported:

• int: Select a single element. Raise error if the data has no batch dimension.

• ndarray[bool]: Select multiple elements based on a boolean mask.

• DisjointIndices: Select multiple non-contiguous elements.

reset(model)

Reset the scene data with the given model.

Reinitializes all simulation state variables using the provided model.

参数:

model (SceneModel) -- The scene model to reset the data with.

set_dof_pos(dof_pos, model)

Set the dof position for the whole world data.

参数:

• dof_pos (NDArray[float]) -- The dof position array to set. If Shape: (*data.shape, num_dof_pos), each data will use the corresponding slice. If Shape: (num_dof_pos,), all data will use the same dof position.

• model (SceneModel) -- The scene model to validate the dof position.

抛出:

Exception -- When the dof position data is invalid.(e.g. quaternion not normalized)

备注

The dof_pos array must follow the same format as the getter method:

• Floating base/free body: 7 elements [tx, ty, tz, qx, qy, qz, qw]

• Ball joint: 4 elements [qx, qy, qz, qw] for quaternion rotation

• Hinge joint: 1 element for angular position

• Slide joint: 1 element for linear position

Elements should be concatenated in order: [floating_base_dofs..., joint1_dofs..., joint2_dofs..., ...]

set_dof_vel(dof_vel)

Set the dof velocity for the whole world data.

参数:

dof_vel (NDArray[float]) -- The dof velocity array to set. Shape: ``(*data.shape,

num_dof_vel)``.

actuator_ctrls

The all the actuator control values. (Get&Set)

Array of actuator control values. Shape: (*data.shape, num_ctrls).

备注

If the model is created from MJCF, the order of the control values matches the order of actuators in the MJCF file.

抛出:

TypeError -- When the shape of the setted values is not invalid.

Type:

NDArray[float]

dof_pos

The dof position array of the world.

Array of DoF positions. Shape: (*data.shape, num_dof_pos)

备注

The dof_pos array contains position coordinates for all degrees of freedom in the simulation, with format varying by joint type:

• Floating base/free body: 7 elements [tx, ty, tz, qx, qy, qz, qw]

• Ball joint: 4 elements [qx, qy, qz, qw] for quaternion rotation

• Hinge joint: 1 element for angular position

• Slide joint: 1 element for linear position

Elements are concatenated in order: [floating_base_dofs..., joint1_dofs..., joint2_dofs..., ...]

Type:

NDArray[float]

dof_vel

The dof velocity array of the world.

Array of DoF velocities. Shape: (*data.shape, num_dof_vel).

Type:

NDArray[float]

low

The low-level data object for advanced simulation control.

备注

Only modify the low-level data if you understand the implications. Incorrect modifications may lead to unstable simulation behavior.

Type:

LowData

ndim

The number of dimensions of the data.

Type:

int

shape

The shape of the data.

If the data is batched, the shape is (batch_size,). If not batched, the shape is ().

Type:

Tuple[int]

class motrixsim.SceneModel

基类：object

The SceneModel object represents the entire simulation world.

This class provides a high-level interface to access and manipulate the simulation world model, including all bodies, joints, actuators, links, and sites. Users can query the scene structure and configuration, modify simulation options, and access components through properties (joints, options) or methods (get_body(), get_sensor_values()).

Methods:

compute_init_dof_pos()	Compute the initial DoF positions for the world.
enable_constraints_report()	Enable constraint report generation for subsequent simulation steps.
forward_kinematic(data)	Perform forward kinematic calculations using the current model and data.
get_actuator(arg)	Get an actuator by name or index.
get_actuator_ctrls(data)	Alias to SceneData.actuator_ctrls()
get_actuator_index(name)	Get actuator index by its name.
get_body(key)	Get a body by name or index.
get_body_index(name)	Get the body index by its name.
get_camera_poses(data)	Get the world poses of all cameras.
get_contact_query(data)	Get a contact query object for the current model and data.
get_geom(arg)	Get a geom by name or index.
get_geom_index(name)	Get the geometry index by its name.
get_gravity_override(data)	Get the effective gravity override from the scene data.
get_hfield(arg)	Get an hfield by name or index.
get_hfield_index(name)	Get hfield index by its name.
get_joint(key)	Get a joint by name or index.
get_joint_index(name)	Get the joint index by its name.
get_link(arg)	Get a link by name or index.
get_link_angular_velocities(data)	Get the world angular velocities of all links.
get_link_index(name)	Get the link index by its name.
get_link_linear_velocities(data)	Get the world linear velocities of all links.
get_link_poses(data)	Get the world poses of all links.
get_link_rotation_mats(data)	Get all link rotation matrices.
get_link_velocities(data)	Get the world velocities (linear and angular) of all links.
get_sensor_value(id, data)	Get the value of a specific sensor by its ID.
get_sensor_values(names, data)	Get the values of multiple sensors by their names, concatenated into a single array.
get_site(key)	Get a site by name or index.
get_site_index(name)	Get site index by name.
set_gravity_override(data, gravity)	Override the gravity vector for the scene data.
step(data)	Advance the simulation by one step using the current model and data.
step_n(data, n)	Advance the simulation by n steps using the current model and data.

Attributes:

actuator_ctrl_limits	The actuator control ranges.
actuator_names	The list of actuator names in the world.
actuators	Get all actuators defined in the model.
bodies	The list of all bodies in the world.
body_names	The list of all body names in the world.
cameras	The camera manager for accessing cameras by name.
floating_bases	The list of all floating bases in the world.
geom_names	The list of all geoms names in the world.
geoms	The list of all geoms in the world.
joint_dof_pos_indices	The start dof index for each joint in the dof positions array.
joint_dof_pos_nums	The number of DoF positions for each joint.
joint_dof_vel_indices	The start dof index for each joint in the dof velocities array.
joint_dof_vel_nums	The size of DoF velocities of each joint.
joint_limits	The joint position limits for each joint.
joint_names	The list of all joint names in the world.
joints	The list of all joints in the world.
keyframes	The list of all keyframes in the model.
link_names	The list of all link names in the world.
links	The list of all links in the world.
low	The low-level model for advanced or internal simulation access.
num_actuators	The number of actuators in the world.
num_bodies	The number of bodies in the world.
num_dof_pos	The number of DoF positions in the world.
num_dof_vel	The number of DoF velocities in the world.
num_geoms	The number of geoms in the world.
num_hfields	The number of height fields in the world.
num_joints	The number of joints in the world.
num_keyframes	The number of keyframes in the model.
num_links	The number of links in the world.
num_sensors	The number of sensors in the world.
num_sites	The number of sites in the world.
options	The simulation options of the model.
site_names	The list of all site names in the world.
sites	The list of all sites in the world.

compute_init_dof_pos()

Compute the initial DoF positions for the world.

返回:

shape=(num_dof_pos,). Initial DoF positions.

返回类型:

NDArray[float]

enable_constraints_report()

Enable constraint report generation for subsequent simulation steps.

备注

This is a model-wide persistent switch shared by all report consumers.

forward_kinematic(data)

Perform forward kinematic calculations using the current model and data.

备注

This method only updates the world poses of all links and bodies based on the current joint positions.

get_actuator(arg)

Get an actuator by name or index.

参数:

key (str or int) -- Name or index of the actuator.

返回:

The actuator object, or None if not found.

返回类型:

Optional[Actuator]

get_actuator_ctrls(data)

Alias to SceneData.actuator_ctrls()

get_actuator_index(name)

Get actuator index by its name.

参数:

name (str) -- Name of the actuator.

返回:

Index of the actuator, or None if not found.

返回类型:

Optional[int]

get_body(key)

Get a body by name or index.

参数:

key (str or int) -- Name or index of the body.

返回:

The body object, or None if not found.

返回类型:

Optional[Body]

get_body_index(name)

Get the body index by its name.

参数:

name (str) -- Name of the body.

返回:

Index of the body, or None if not found.

返回类型:

Optional[int]

get_camera_poses(data)

Get the world poses of all cameras.

参数:

data (SceneData) -- Scene data.

返回:

A numpy array with shape (*data.shape,num_cameras, 7). Each pose is composed of [x, y, z, qx, qy, qz, qw],

返回类型:

NDArray[float]

备注

If there are no cameras in the scene, returns an array with shape (*data.shape, 0, 7).

get_contact_query(data)

Get a contact query object for the current model and data.

参数:

data (SceneData) -- Scene data.

返回:

A contact query object that can be used to query contacts in the world.

返回类型:

ContactQuery

get_geom(arg)

Get a geom by name or index.

参数:

key (str or int) -- Name or index of the geom.

返回:

The geom object, or None if not found.

返回类型:

Optional[Geom]

get_geom_index(name)

Get the geometry index by its name.

参数:

name (str) -- Name of the geometry.

返回:

Index of the geometry, or None if not found.

返回类型:

Optional[int]

get_gravity_override(data)

Get the effective gravity override from the scene data.

参数:

data (SceneData) -- Scene data.

返回:

Gravity vector. Shape: (*data.shape, 3).

返回类型:

NDArray[float]

get_hfield(arg)

Get an hfield by name or index.

参数:

key (str or int) -- Name or index of the hfield.

返回:

The hfield object, or None if not found.

返回类型:

Optional[HField]

get_hfield_index(name)

Get hfield index by its name.

参数:

name (str) -- Name of the hfield.

返回:

Index of the hfield, or None if not found.

返回类型:

Optional[int]

get_joint(key)

Get a joint by name or index.

参数:

key (str or int) -- Name or index of the joint.

返回:

The joint object, or None if not found.

返回类型:

Optional[Joint]

get_joint_index(name)

Get the joint index by its name.

参数:

name (str) -- Name of the joint.

返回:

Index of the joint, or None if not found.

返回类型:

Optional[int]

get_link(arg)

Get a link by name or index.

参数:

key (str or int) -- Name or index of the link.

返回:

The link object, or None if not found.

返回类型:

Optional[Link]

get_link_angular_velocities(data)

Get the world angular velocities of all links.

参数:

data (SceneData) -- Scene data.

返回:

A numpy array with shape (*data.shape, num_links, 3). Each velocity is composed of [wx, wy, wz].

返回类型:

NDArray[float]

get_link_index(name)

Get the link index by its name.

参数:

name (str) -- Name of the link.

返回:

Index of the link, or None if not found.

返回类型:

Optional[int]

get_link_linear_velocities(data)

Get the world linear velocities of all links.

参数:

data (SceneData) -- Scene data.

返回:

A numpy array with shape (*data.shape, num_links, 3). Each velocity is composed of [vx, vy, vz].

返回类型:

NDArray[float]

get_link_poses(data)

Get the world poses of all links.

参数:

data (SceneData) -- Scene data.

返回:

A numpy array with shape (*data.shape,num_links, 7). Each pose is composed of [x, y, z, i, j, k, w],

返回类型:

NDArray[float]

get_link_rotation_mats(data)

Get all link rotation matrices.

参数:

data (SceneData) -- Scene data.

返回:

A numpy array with shape (*data.shape,num_links, 3, 3). Each rotation

返回类型:

NDArray[float]

matrix is in column-major order.

get_link_velocities(data)

Get the world velocities (linear and angular) of all links.

参数:

data (SceneData) -- Scene data.

返回:

A numpy array with shape (*data.shape, num_links, 6). Each velocity is composed of [vx, vy, vz, wx, wy, wz].

返回类型:

NDArray[float]

get_sensor_value(id, data)

Get the value of a specific sensor by its ID.

参数:

• id (str) -- Sensor ID.

• data (SceneData) -- Scene data.

返回:

Sensor values. Shape: (*data.shape, sensor_value_size)

返回类型:

NDArray[float]

get_sensor_values(names, data)

Get the values of multiple sensors by their names, concatenated into a single array.

参数:

• names (List[str]) -- List of sensor names.

• data (SceneData) -- Scene data.

返回:

Concatenated sensor values with shape (*data.shape, total_sensor_values) where total_sensor_values is the sum of all queried sensors' value sizes.

返回类型:

NDArray[float]

get_site(key)

Get a site by name or index.

参数:

key (str or int) -- Name or index of the site.

返回:

The site object, or None if not found.

返回类型:

Optional[Site]

get_site_index(name)

Get site index by name.

参数:

name (str) -- Name of the site.

返回:

Index of the site, or None if not found.

返回类型:

Optional[int]

set_gravity_override(data, gravity)

Override the gravity vector for the scene data.

参数:

• data (SceneData) -- Scene data to modify.

• gravity (NDArray[float]) -- The new gravity vector. - Shape (3,): Single value applied to all batches - Shape (*data.shape, 3): Per-batch values

备注

If any gravity component is NaN or infinite, the override will be ignored.

step(data)

Advance the simulation by one step using the current model and data.

备注

If the data has batch dimension, motrixsim will run simulation in parallel

step_n(data, n)

Advance the simulation by n steps using the current model and data.

参数:

• data (SceneData) -- Scene data.

• n (int) -- Number of steps to advance the simulation.

备注

This method can skip the python overhead when stepping multiple times.

actuator_ctrl_limits

The actuator control ranges.

Return a 2-dimensional numpy array with shape (2, num_actuators). The first dimension is the minimum control value, and the second dimension is the maximum control value. If the limits do not set for a actuator, (-inf, inf) will be used as the limits.

Type:

NDArray[float]

actuator_names

The list of actuator names in the world.

Return list of actuator names, can be None if the actuator does not have a name.

Type:

List[Optional[str]]

actuators

Get all actuators defined in the model.

返回:

A list of all actuator objects in the world.

返回类型:

List[Actuator]

bodies

The list of all bodies in the world.

备注

don't confuse the body in motrixsim with the body in mjcf. See 🤖 刚体 for more details.

Type:

List[Body]

body_names

The list of all body names in the world.

Return list of body names, can be None if the body does not have a name.

Type:

List[Optional[str]]

cameras

The camera manager for accessing cameras by name.

Type:

CameraMgr

floating_bases

The list of all floating bases in the world.

Type:

List[FloatingBase]

geom_names

The list of all geoms names in the world.

A list of geom names, can be None if the geom does not have a name.

Type:

List[Optional[str]]

geoms

The list of all geoms in the world.

Type:

List[Geom]

joint_dof_pos_indices

The start dof index for each joint in the dof positions array.

A list of start indices for each joint's dof positions in the dof positions array. size = num_joints.

备注

The DoF of floating base is not included.

Type:

List[int]

joint_dof_pos_nums

The number of DoF positions for each joint.

List of position DoF sizes for each joint. size = num_joints

Type:

List[int]

joint_dof_vel_indices

The start dof index for each joint in the dof velocities array.

A list of start indices for each joint's dof velocities in the dof velocities array.

备注

The DoF of floating base is not included.

Type:

List[int]

joint_dof_vel_nums

The size of DoF velocities of each joint.

List of velocity DoF sizes for each joint. size = num_joints.

Type:

List[int]

joint_limits

The joint position limits for each joint.

A 2-dimensional numpy array with shape (2, num_joints).

The first dimension is the minimum position limit, and the second dimension is the maximum position limit. If the limits are not set for a joint, -inf, inf will be used as the limits.

Type:

NDArray[float]

joint_names

The list of all joint names in the world.

Return list of joint names, can be None if the joint does not have a name.

Type:

List[Optional[str]]

joints

The list of all joints in the world.

Type:

List[Joint]

keyframes

The list of all keyframes in the model.

Type:

List[Keyframe]

link_names

The list of all link names in the world.

A list of link names, can be None if the link does not have a name.

Type:

List[Optional[str]]

links

The list of all links in the world.

Type:

List[Link]

low

The low-level model for advanced or internal simulation access.

This property exposes the underlying low-level scene model, which provides direct access to internal simulation data and advanced features.

备注

Do not use this property unless you know what you are doing.

Type:

LowSceneModel

num_actuators

The number of actuators in the world.

Type:

int

num_bodies

The number of bodies in the world.

Type:

int

num_dof_pos

The number of DoF positions in the world.

Type:

int

num_dof_vel

The number of DoF velocities in the world.

备注

This value may be different from the [num_dof_pos] because for some joint (like ball joint), we use Quaternion to represent the rotation, which has 4 components.

Type:

int

num_geoms

The number of geoms in the world.

Type:

int

num_hfields

The number of height fields in the world.

Type:

int

num_joints

The number of joints in the world.

备注

freejoint in MJCF is not considered as a joint but a floating base.

Type:

int

num_keyframes

The number of keyframes in the model.

Type:

int

num_links

The number of links in the world.

备注

The worldbody in MJCF is not considered as a link.

Type:

int

num_sensors

The number of sensors in the world.

Type:

int

num_sites

The number of sites in the world.

Type:

int

options

The simulation options of the model.

Type:

Options

site_names

The list of all site names in the world.

Type:

List[str]

sites

The list of all sites in the world.

Type:

List[Site]

class motrixsim.Shape

基类：object

The source shape type of a high-level geometry.

This mirrors Rust's msd::geom::ShapeType / GeometryShape and describes the user-facing geometry before compile-time lowering. A mesh high-level shape may lower to one or more low-level runtime collider shapes.

Methods:

type_names()	Returns all high-level source shape type names as a list of strings.
types()	Returns all high-level source shape types as a list.

Attributes:

Capsule
Cuboid
Cylinder
Ellipsoid
HField
InfinitePlane
Mesh
Plane
Sphere

static type_names()

Returns all high-level source shape type names as a list of strings.

返回:

All high-level source shape type names.

返回类型:

List[str]

static types()

Returns all high-level source shape types as a list.

返回:

All high-level source shape types.

返回类型:

List[Shape]

Capsule = Shape.Capsule

Cuboid = Shape.Cuboid

Cylinder = Shape.Cylinder

Ellipsoid = Shape.Ellipsoid

HField = Shape.HField

InfinitePlane = Shape.InfinitePlane

Mesh = Shape.Mesh

Plane = Shape.Plane

Sphere = Shape.Sphere

class motrixsim.Site

基类：object

The Site object represents a reference point or marker in the scene.

Methods:

get_jacobian(data)	Get the compact Jacobian matrix of the site.
get_pose(data)	Get the pose of the site in the world frame.
get_position(data)	Get the position of the site in the world frame.
get_rotation_mat(data)	Get the rotation matrix of the site in the world frame.

Attributes:

dof_vel_indices	Global DoF velocity indices that affect this site.
index	The index of the site in the site list.
local_pos	The local position of the site in the parent frame in (x, y, z).
local_quat	The local orientation of the site as a quaternion (i, j, k, w).
model	The model that this site belongs to.
name	The name of the site, or None if not set.
parent_link	The parent link of the site, or None if the site is attached to the world frame.

get_jacobian(data)

Get the compact Jacobian matrix of the site.

The Jacobian maps DoF velocities to the site's spatial velocity in world frame. Only columns corresponding to dof_vel_indices are included.

参数:

data (SceneData) -- The scene data containing the current state.

返回:

Shape (*data.shape, 6, k) where k equals

len(self.dof_vel_indices). The first 3 rows are angular velocity, the last 3 rows are linear velocity.

返回类型:

NDArray[float]

get_pose(data)

Get the pose of the site in the world frame.

参数:

data (SceneData) -- The scene data to query.

返回:

The pose of the site in the world frame. Shape: (*data.shape,7). The last axis is 7-element array with [x, y, z, i, j, k, w].

返回类型:

NDArray[float]

get_position(data)

Get the position of the site in the world frame.

参数:

data (SceneData) -- The scene data to query.

返回:

The position of the site in the world frame. Shape: (*data.shape,3).

返回类型:

NDArray[float]

get_rotation_mat(data)

Get the rotation matrix of the site in the world frame.

参数:

data (SceneData) -- The scene data to query.

返回:

The rotation matrix of the site in the world frame. shape =

(*data.shape,3,3).

返回类型:

NDArray[float]

dof_vel_indices

Global DoF velocity indices that affect this site.

返回:

Shape (k,) where k is the number of DoFs on the kinematic path

from root to this site's parent link.

返回类型:

NDArray[int]

备注

This is a model property determined by the kinematic tree topology. It does not depend on simulation state and can be cached by the user.

index

The index of the site in the site list.

Type:

int

local_pos

The local position of the site in the parent frame in (x, y, z).

Type:

NDArray[float]

local_quat

The local orientation of the site as a quaternion (i, j, k, w).

Type:

NDArray[float]

model

The model that this site belongs to.

name

The name of the site, or None if not set.

Type:

Optional[str]

parent_link

The parent link of the site, or None if the site is attached to the world frame.

Type:

Link

class motrixsim.TerrainScanner(terrain, frame, offsets, alignment='yaw', output='height')

基类：object

A scanner object for batched frame-relative terrain height sampling.

TerrainScanner caches all static parameters (terrain geom, reference frame, scan offsets, alignment mode, output mode) at construction time so that the hot-path scan() call only reads batched poses and writes results — no parameter parsing, no temporary array allocation.

Typical usage for RL locomotion height-scan:

scanner = motrixsim.TerrainScanner(
    terrain=hfield_geom,
    frame=base_link,
    offsets=scan_offsets,       # shape (N, 2)
    alignment="yaw",
    output="height",
)

# in step loop (hot path)
heights = scanner.scan(data, out=buffer)

参数:

• terrain (GeomHField) -- The height-field geom to sample.

• frame (Link) -- The reference frame whose pose drives the scan.

• offsets (NDArray[float]) -- Frame-local XY scan points, shape (N, 2).

• alignment (str) -- How the frame orientation is projected. "yaw" — only the heading (rotation about world Z) is used; roll and pitch are ignored.

• output (str) -- What quantity to return. "height" — terrain surface world-Z coordinate. "clearance" — frame_z - terrain_height, i.e. vertical distance from the frame origin to the terrain surface below each scan point.

Methods:

scan(data[, out])

Perform a batched terrain height scan.

scan(data, out=None)

Perform a batched terrain height scan.

For each batch instance the method reads the frame link pose, extracts the yaw heading, rotates each local offset into world XY, samples the terrain height via bilinear interpolation, and writes the result.

参数:

• data (SceneData) -- The scene data (batched or single).

• out (Optional[NDArray[float]]) -- Pre-allocated output buffer of shape (*data.shape, N) where N is the number of scan points. When provided, the result is written in-place and returned directly, avoiding an internal allocation.

返回:

Shape (*data.shape, N).

When output="height", each element is the terrain surface world-Z at the corresponding scan point. When output="clearance", each element is frame_z - terrain_height.

返回类型:

NDArray[float]

class motrixsim.VelocityActuator

基类：Actuator

Velocity actuator (MJCF <velocity>).

MJCF parameter mapping:

• kv -> kv (writes both gain and damping internally)

Methods:

get_kv_override(data)	Get the kv override value from the scene data.
set_kv_override(data, kv)	Override the kv value for a velocity actuator.

get_kv_override(data)

Get the kv override value from the scene data.

参数:

data (SceneData) -- The scene data to query.

返回:

The kv value. Shape: (*data.shape,)

返回类型:

NDArray[float]

set_kv_override(data, kv)

Override the kv value for a velocity actuator. Writes both gain and damping.

参数:

• data (SceneData) -- The scene data to modify.

• kv (NDArray[float]) -- The new kv value. - Shape (): Single value applied to all batches - Shape: (*data.shape,): Per-batch values

备注

Raises ValueError if the value is negative, NaN, infinite, or the actuator is not a velocity actuator.

motrixsim.forward_kinematic(model, data)

Run forward kinematic only.

参数:

• model (SceneModel) -- The scene model.

• data (SceneData) -- The scene data.

motrixsim.load_mjcf_str(mjcf)

Load a model from a string containing MJCF data.

参数:

mjcf (str) -- The MJCF data as a string.

返回:

The loaded scene model.

返回类型:

SceneModel

motrixsim.load_model(path)

Load a model from the given file path.

参数:

• path (str) -- The path to the model file.

• supported. (currently mjcf and urdf are)

返回:

The loaded scene model.

返回类型:

SceneModel

motrixsim.step(model, data)

Advance the simulation by one step.

参数:

• model (SceneModel) -- The scene model.

• data (SceneData) -- The scene data.