pid_control

The pid_control package provides a ROS 2 node that implements dual PID control loops for steering and velocity. It is designed to interface with the OSCC (Open Source Car Control) system by outputting combined control commands.

Overview

The pid_control_node subscribes to desired vehicle states (steering angle and speed) and real-time feedback from sensors. It computes error signals for both steering and velocity independently, applies PID control logic with anti-windup, and publishes a Roscco message containing the required steering torque and velocity commands.

Node: pid_control_node

Subscriptions

Publishers

Parameters

General

• update_rate (double, default: 100.0): Frequency (Hz) of the PID control loop.

PID Configuration (steering_pid and velocity_pid namespaces)

Both steering and velocity controllers share the same parameter structure:

• p (double): Proportional gain.
• i (double): Integral gain.
• d (double): Derivative gain.
• i_clamp_max (double): Upper bound for the integrator term (anti-windup).
• i_clamp_min (double): Lower bound for the integrator term.
• u_clamp_max (double): Upper saturation limit for the controller output.
• u_clamp_min (double): Lower saturation limit for the controller output.
• saturation (bool): Whether to enforce output saturation limits.
• antiwindup (bool): Enable anti-windup/integrator correction.
• antiwindup_strategy (string): Strategy for anti-windup (recommended: conditional_integration).

Usage

Launching the node

The node can be launched using the provided launch file, which automatically loads the configuration from pid_control.yaml:

ros2 launch pid_control pid_control.launch.yaml

Anti-Windup Strategy

This package uses the conditional_integration strategy by default. This is a modern anti-windup method provided by control_toolbox that silences legacy deprecation warnings while providing robust integrator behavior during actuator saturation.