Configuration

Configuration space of a robot model.

The Configuration class encapsulates a MuJoCo model and data, offering easy access to frame transforms and frame Jacobians. A frame refers to a coordinate system that can be attached to various parts of the robot, such as a body, geom, or site.

class mink.configuration.Configuration

Encapsulates a model and data for convenient access to kinematic quantities.

This class provides methods to access and update the kinematic quantities of a robot model, such as frame transforms and Jacobians. It performs forward kinematics at every time step, ensuring up-to-date information about the robot’s state.

Key functionalities include:

Running forward kinematics to update the state.
Checking configuration limits.
Computing Jacobians for different frames.
Retrieving frame transforms relative to the world frame.
Integrating velocities to update configurations.

update(q: ndarray | None = None) → None

Run forward kinematics.

Parameters:: q (ndarray | None) – Optional configuration vector to override internal data.qpos with.
Return type:: None

update_from_keyframe(key_name: str) → None

Update the configuration from a keyframe.

Parameters:: key_name (str) – The name of the keyframe.
Return type:: None

check_limits(tol: float = 1e-06, safety_break: bool = True) → None

Check that the current configuration is within bounds.

Parameters:

tol (float) – Tolerance in [rad].
safety_break (bool) – If True, stop execution and raise an exception if the current configuration is outside limits. If False, print a warning and continue execution.

Return type:

None

get_frame_jacobian(frame_name: str, frame_type: str) → ndarray

Compute the Jacobian matrix of a frame velocity.

Denoting our frame by \(B\) and the world frame by \(W\), the Jacobian matrix \({}_B J_{WB}\) is related to the body velocity \({}_B v_{WB}\) by:

\[{}_B v_{WB} = {}_B J_{WB} \dot{q}\]

Parameters:

frame_name (str) – Name of the frame in the MJCF.
frame_type (str) – Type of frame. Can be a geom, a body or a site.

Returns:

Jacobian \({}_B J_{WB}\) of the frame.

Return type:

ndarray

get_transform_frame_to_world(frame_name: str, frame_type: str) → SE3

Get the pose of a frame at the current configuration.

Parameters:

frame_name (str) – Name of the frame in the MJCF.
frame_type (str) – Type of frame. Can be a geom, a body or a site.

Returns:

The pose of the frame in the world frame.

Return type:

SE3

get_transform(source_name: str, source_type: str, dest_name: str, dest_type: str) → SE3

Get the pose of a frame with respect to another frame at the current configuration.

Parameters:

source_name (str) – Name of the frame in the MJCF.
source_type (str) – Source type of frame. Can be a geom, a body or a site.
dest_name (str) – Name of the frame to get the pose in.
dest_type (str) – Dest type of frame. Can be a geom, a body or a site.

Returns:

The pose of source_name in dest_name.

Return type:

SE3

integrate(velocity: ndarray, dt: float) → ndarray

Integrate a velocity starting from the current configuration.

Parameters:

velocity (ndarray) – The velocity in tangent space.
dt (float) – Integration duration in [s].

Returns:

The new configuration after integration.

Return type:

ndarray

integrate_inplace(velocity: ndarray, dt: float) → None

Integrate a velocity and update the current configuration inplace.

Parameters:

velocity (ndarray) – The velocity in tangent space.
dt (float) – Integration duration in [s].

Return type:

None

property q: ndarray: The current configuration vector.

property nv: int: The dimension of the tangent space.

property nq: int: The dimension of the configuration space.