franky.CartesianImpedanceMotion

class franky.CartesianImpedanceMotion

Bases: CartesianImpedanceBase

Cartesian impedance motion.

This motion implements a cartesian impedance controller on the client side and does not use Franka’s internal impedance controller. Instead, it uses Franka’s internal torque controller and calculates the torques itself.

Analogous to JointImpedanceMotion, this motion regulates toward a fixed target pose (and optional target twist) and does not terminate on its own. It runs until it is preempted or stopped.

__init__(self: franky._franky.CartesianImpedanceMotion, target: franky._franky.Affine, target_twist: franky._franky.Twist | None = None, target_type: franky._franky.ReferenceType = _franky.ReferenceType.Absolute, translational_stiffness: SupportsFloat | SupportsIndex = 500, rotational_stiffness: SupportsFloat | SupportsIndex = 50, force_constraints: Annotated[collections.abc.Sequence[SupportsFloat | SupportsIndex | None], 'FixedSize(6)'] | None = None, posture_task: franky._franky.PostureTask | None = None, manipulability_task: franky._franky.ManipulabilityTask | None = None, max_delta_tau: SupportsFloat | SupportsIndex = 1.0, lower_joint_limits: Annotated[numpy.typing.ArrayLike, numpy.float64, '[7, 1]'] | None = None, upper_joint_limits: Annotated[numpy.typing.ArrayLike, numpy.float64, '[7, 1]'] | None = None, joint_limit_activation_distance: SupportsFloat | SupportsIndex = 0.1, joint_limit_stiffness: SupportsFloat | SupportsIndex = 4.0, joint_limit_damping: SupportsFloat | SupportsIndex = 1.0, joint_limit_max_torque: SupportsFloat | SupportsIndex = 5.0, translational_error_clip: Annotated[numpy.typing.ArrayLike, numpy.float64, '[3, 1]'] = array([0.1, 0.1, 0.1]), rotational_error_clip: Annotated[numpy.typing.ArrayLike, numpy.float64, '[3, 1]'] = array([0.25, 0.25, 0.25]), friction: franky._franky.FrictionCompensationParams | None = None) → None

Construct a Cartesian impedance motion that regulates toward a fixed target pose.

Like JointImpedanceMotion, this motion does not finish on its own; it keeps regulating toward the target until it is preempted or stopped.

If target_twist is provided, it is interpreted as the desired end-effector twist in the base frame and the damping term acts on twist error rather than damping all motion toward zero.

Cartesian damping is chosen internally as critically damped with respect to the requested stiffness.

The optional posture_task adds a secondary joint-posture objective (a PostureTask) that is projected into the Jacobian nullspace, biasing the redundant arm posture without changing the Cartesian task to first order. Its per-joint stiffness leaves zero-stiffness joints unpushed. manipulability_task adds a manipulability-maximization objective in the same nullspace. At most one of each is supported.

add_reaction(self: franky._franky.BaseTorqueMotion, reaction: franky._franky.TorqueReaction) → None

Add a reaction to the motion.

Reactions are evaluated in every step of the motion and can replace the current motion with a new motion.

Parameters:

reaction – The reaction to add.

Warning

Do not call this function synchronously from a condition, motion function, or reaction callback while this motion’s reactions are being evaluated. Reaction evaluation holds the reaction-list mutex, so doing so would deadlock.

get_gains(self: franky._franky.CartesianImpedanceBase) → franky._franky.CartesianImpedanceGains

Get a copy of the current target impedance gains.

Mutating the returned object has no effect on the motion; pass it to setGains to apply changes.

get_nullspace_gains(self: franky._franky.CartesianImpedanceBase) → franky._franky.NullspaceGains

Get a copy of the current target nullspace gains.

Mutating the returned object has no effect on the motion; pass it to setNullspaceGains to apply changes.

register_callback(self: franky._franky.BaseTorqueMotion, callback: collections.abc.Callable[[franky._franky.RobotState, franky._franky.Duration, franky._franky.Duration, franky._franky.Duration, franky._franky.Torques], None]) → None

Register a callback that is called in every step of the motion.

Parameters:

callback – The callback to register. Callbacks are called with the robot state, the time step [s], the relative time [s], the absolute time [s] and the control signal computed in this step.

set_gains(self: franky._franky.CartesianImpedanceBase, gains: franky._franky.CartesianImpedanceGains) → None

Set the target impedance gains.

The gains are validated and then smoothed in the control loop via exponential interpolation.

Parameters:

gains – The new target gains.

set_nullspace_gains(self: franky._franky.CartesianImpedanceBase, gains: franky._franky.NullspaceGains) → None

Set the target nullspace gains.

The gains are smoothed in the control loop via exponential interpolation.

Parameters:

gains – The new target nullspace gains.

property params

property reactions

Currently registered reactions of the motion.

property target

The target pose of the motion.

property target_twist