LTVUnicycleController

class wpimath.controller.LTVUnicycleController(*args, **kwargs)

Bases: pybind11_object

The linear time-varying unicycle controller has a similar form to the LQR, but the model used to compute the controller gain is the nonlinear model linearized around the drivetrain’s current state.

See section 8.9 in Controls Engineering in FRC for a derivation of the control law we used shown in theorem 8.9.1.

Overloaded function.

  1. __init__(self: wpimath._controls._controls.controller.LTVUnicycleController, dt: seconds, maxVelocity: meters_per_second = 9.0) -> None

Constructs a linear time-varying unicycle controller with default maximum desired error tolerances of (0.0625 m, 0.125 m, 2 rad) and default maximum desired control effort of (1 m/s, 2 rad/s).

Parameters:

  • dt – Discretization timestep.

  • maxVelocity – The maximum velocity for the controller gain lookup table. @throws std::domain_error if maxVelocity <= 0.

  1. __init__(self: wpimath._controls._controls.controller.LTVUnicycleController, Qelems: Tuple[float, float, float], Relems: Tuple[float, float], dt: seconds, maxVelocity: meters_per_second = 9.0) -> None

Constructs a linear time-varying unicycle controller.

Parameters:

  • Qelems – The maximum desired error tolerance for each state.

  • Relems – The maximum desired control effort for each input.

  • dt – Discretization timestep.

  • maxVelocity – The maximum velocity for the controller gain lookup table. @throws std::domain_error if maxVelocity <= 0.

atReference() → bool

Returns true if the pose error is within tolerance of the reference.

calculate(*args, **kwargs)

Overloaded function.

  1. calculate(self: wpimath._controls._controls.controller.LTVUnicycleController, currentPose: wpimath.geometry._geometry.Pose2d, poseRef: wpimath.geometry._geometry.Pose2d, linearVelocityRef: meters_per_second, angularVelocityRef: radians_per_second) -> wpimath.kinematics._kinematics.ChassisSpeeds

Returns the linear and angular velocity outputs of the LTV controller.

The reference pose, linear velocity, and angular velocity should come from a drivetrain trajectory.

Parameters:

  • currentPose – The current pose.

  • poseRef – The desired pose.

  • linearVelocityRef – The desired linear velocity.

  • angularVelocityRef – The desired angular velocity.

  1. calculate(self: wpimath._controls._controls.controller.LTVUnicycleController, currentPose: wpimath.geometry._geometry.Pose2d, desiredState: wpimath._controls._controls.trajectory.Trajectory.State) -> wpimath.kinematics._kinematics.ChassisSpeeds

Returns the linear and angular velocity outputs of the LTV controller.

The reference pose, linear velocity, and angular velocity should come from a drivetrain trajectory.

Parameters:

  • currentPose – The current pose.

  • desiredState – The desired pose, linear velocity, and angular velocity from a trajectory.

setEnabled(enabled: bool) → None

Enables and disables the controller for troubleshooting purposes.

Parameters:

enabled – If the controller is enabled or not.

setTolerance(poseTolerance: wpimath.geometry._geometry.Pose2d) → None

Sets the pose error which is considered tolerable for use with AtReference().

Parameters:

poseTolerance – Pose error which is tolerable.