lqr_controller

Static state-feedback controller for an lqr artifact.

Law. u = u_eq − K·(x − x_ref), where x = [q − q_eq, q̇] is the deviation state and x_ref the (deviation) setpoint. With the default reference the controller regulates to the operating point (x_ref = 0), so u = u_eq − K·x.

Artifact. Requires a static gain K of shape n_actuated × 2·n_joints (no ctrl_*). Loading an lqg/hinf artifact is rejected at configure time.

Interfaces.

  • Commands: effort on each actuated joint.

  • States: position and velocity on every joint (the law needs the full state).

  • References (chainable): <joint>/position then <joint>/velocity, absolute units; defaults are q_eq / 0.

Parameters. artifact_path, command_interface (default effort), state_position_interface, state_velocity_interface, and the validity.* guard settings. No discretization, so update_rate is irrelevant here.

Demo

ros2 launch lqr_controller lqr_demo.launch.py

Balances the cart–double-inverted-pendulum on mock hardware (plumbing proof). For physics stabilization, drive the same artifact through Gazebo Fortress (headless, in CI) or Isaac Sim (local GPU).