PID Controller Module

Author: Pranav Rayapureddi

Purpose

A generic, reusable PID controller for any closed-loop control application. Integral windup is clamped to configurable limits set at initialization.

How It Works

computePID() implements a standard discrete PID:

• dt is computed from FreeRTOS tick counts via xTaskGetTickCount() / configTICK_RATE_HZ.
• Anti-windup: integral is hard-clamped each iteration to the limits set in pidConfig().
• Caller is responsible for clamping to actuator limits.

Integration

PID myController;
pidConfig(&myController, WINDUP_MAX, WINDUP_MIN);

// In control loop:
float output = computePID(&myController, setPoint, input, KP, KI, KD);

pidReset() zeroes the integral, previous error, and timestamp — use it when re-enabling a controller after a fault or mode switch to prevent state carryover.

Limitations

• Gains (Kp, Ki, Kd) are passed per-call rather than stored in the struct — caller must ensure consistent gains across iterations.