motrixsim

Classes:

Actuator	The Actuator object represents a controllable actuator in the simulation.
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.
Geom	The Geom object represents a geometry in the scene.
HField	The HField object represents a height field terrain in the scene.
Joint	The Joint object represents a joint 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.
Options	The Options object represents the simulation options.
SceneData(model[, batch])	The SceneData object represents the simulation state.
SceneModel	The SceneModel object represents the entire simulation world.
Site	The Site object represents a reference point or marker in the scene.

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.

class motrixsim.Actuator

基类：object

The Actuator object represents a controllable actuator in the simulation.

This class provides access to the properties and methods of an actuator, allowing users to query its name, index, control range, and set the control value.

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.
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. If the data has batch dimension, ctrl must have the same shape as the data.

ctrl_range

The control range of the actuator.

Returns None if not set.

Type:

Optional[Tuple[float, float]]

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.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_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:

floatingbase	The floating base object.
is_mocap	Whether the body is a mocap (kinematic) body.
mocap	Convert this body to a mocap object if it is a mocap body.
name	The name of the 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, y, z, i, j, k, w].

返回类型:

NDArray[float]

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 [i, j, k, w].

返回类型:

NDArray[float]

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_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.

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]

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]

name

The name of the body.

Return None if not present.

Type:

Optional[str]

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.
index	The index of the camera in the motrixsim.SceneModel.cameras().
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.
render_target	Get the render target of the camera, either "window" or "image".

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

index

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

Type:

int

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

render_target

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

Type:

str

class motrixsim.CameraMgr

基类：object

Attributes:

cameras	All the cameras defined in the model.
model	The scene model that this camera manager belongs to.

cameras

All the cameras defined in the model.

Type:

List[Camera]

model

The scene model that this camera manager belongs to.

Type:

SceneModel

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.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.

Methods:

get_angular_velocity(data)	Get the world angular velocity of the geom.
get_linear_velocity(data)	Get the world linear velocity of the geom.
get_pose(data)	Get the world pose of the geom.

Attributes:

index	The index of the geom in the motrixsim.SceneModel.geoms().
model	The scene model that this geom belongs to.
name	The name 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_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]

index

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

Type:

int

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]

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.

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_dof_pos(data)	Get the DoF positions of the joint.
get_dof_vel(data)	Get the DoF velocities 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.

Attributes:

dof_pos_index	The position DoF address of the joint.
dof_vel_index	The velocity DoF address 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.

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]

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())

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

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

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:

get_angular_velocity(data)	Get the world angular velocity of the link.
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_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_mass(mass)	Set the custom mass for a link.

Attributes:

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

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_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_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_mass(mass)

Set the custom mass for a link.

参数:

mass (Real) -- The new mass.

返回:

True if the set operation success. False if fail due to the setting opearation on a Mocap type link or an internal virtual link.

返回类型:

bool

备注

This function change the model directly.

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]

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:

the 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.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?
disable_impedance	Is impedance effects 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

disable_impedance

Is impedance effects 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.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.
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. shape = (*data.shape, num_dof_pos).

• 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

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.
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_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_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_index(name)	Get the link index by its name.
get_link_poses(data)	Get the world poses of all links.
get_link_rotation_mats(data)	Get all link rotation matrices.
get_sensor_value(id, data)	Get the value of a specific sensor by its ID.
get_site(key)	Get a site by name or index.
get_site_index(name)	Get site index by name.
step(data)	Advance the simulation by one step 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	All the cameras in the scene.
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.
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_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]

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_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_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_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_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_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_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]

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

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（Body） 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

All the cameras in the scene.

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]

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_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.Site

基类：object

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

Methods:

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:

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_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]

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

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.