feat(controls): PID auto-tuner (Issue #213) #215

sl-controls · 2026-03-02T11:47:13-05:00

sl-controls commented

2026-03-02 11:47:13 -05:00

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sl-controls added 1 commit 2026-03-02 11:47:14 -05:00

feat: Add Issue #213 - PID auto-tuner (Astrom-Hagglund relay oscillation) fd7eddd44d

Implements PID auto-tuning ROS2 node using relay feedback (Astrom-Hagglund) method.
Service-triggered relay oscillation measures ultimate gain (Ku) and ultimate period
(Tu), then computes Ziegler-Nichols PD gains. Safety abort on >25deg tilt.

Features:
  - Service /saltybot/autotune_pid (std_srvs/Trigger) starts tuning
  - Relay oscillation method for accurate gain measurement
  - Measures Ku (ultimate gain) and Tu (ultimate period)
  - Computes Z-N PD gains: Kp=0.6*Ku, Kd=0.075*Ku*Tu
  - Real-time safety abort >25° tilt angle
  - JSON telemetry on /saltybot/autotune_info
  - Relay commands on /saltybot/autotune_cmd_vel

Tuning Process:
  1. Settle phase: zero command, allow oscillations to die
  2. Relay oscillation: apply +/-relay_magnitude commands
  3. Measure peaks: detect zero crossings, record extrema
  4. Analysis: calculate Ku from peak amplitude, Tu from period
  5. Gain computation: Ziegler-Nichols formulas
  6. Publish results: Ku, Tu, Kp, Kd

Safety Features:
  - IMU tilt monitoring (abort >25°)
  - Max tuning duration timeout
  - Configurable settle time and oscillation cycles

Published Topics:
  - /saltybot/autotune_info (std_msgs/String) - JSON with Ku, Tu, Kp, Kd
  - /saltybot/autotune_cmd_vel (geometry_msgs/Twist) - Relay control

Subscribed Topics:
  - /imu/data (sensor_msgs/Imu) - IMU tilt safety check
  - /saltybot/balance_feedback (std_msgs/Float32) - Balance feedback

Package: saltybot_pid_autotune
Entry point: pid_autotune_node
Service: /saltybot/autotune_pid

Tests: 20+ unit tests covering:
  - IMU tilt extraction
  - Relay oscillation analysis
  - Ku/Tu measurement
  - Ziegler-Nichols gain computation
  - Peak detection and averaging
  - Safety limits (tilt, timeout)
  - State machine transitions
  - JSON telemetry format

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

sl-jetson merged commit a05c93669e into main

2026-03-02 11:48:03 -05:00

sl-jetson referenced this issue from a commit

2026-03-02 11:48:04 -05:00

Merge pull request 'feat(controls): PID auto-tuner (Issue #213)' (#215) from sl-controls/issue-213-autotune into main

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Reference: seb/saltylab-firmware#215