Overview

A proportional-integral-derivative (PID) controller.

Inspired by pid-rs

With cleaner API and assumptions (constant time delta, symmetrical limits) dropped.

Features

• Discrete time PID controller
• Defined for generic float types
• Attempts to conform to rust API Guidelines
• #![no_std]
• Limits for each of p, i, d terms and output
• Calculates derivative term using measurement over error (no derivative kick on new setpoint)
• Clamps time interval to between Float::epsilon() and Float::infinity()

Installation

cargo add pid-ctrl

Examples

```rust let mut pid = super::PidCtrl::newwithpid(3.0, 2.0, 1.0);

let setpoint = 5.0; let prevmeasurement = 0.0; // calling init optional. Setpoint and prevmeasurement set to 0.0 by default. // Recommended to avoid derivative kick on startup pid.init(setpoint, prev_measurement);

let measurement = 0.0; let timedelta = 1.0; asserteq!( pid.step(super::PidIn::new(measurement, time_delta)), super::PidOut::new(15.0, 10.0, 0.0, 25.0) );

// changing pid constants pid.kp.setscale(4.0); asserteq!( pid.step(super::PidIn::new(measurement, time_delta)), super::PidOut::new(20.0, 20.0, 0.0, 40.0) );

// setting symmetrical limits around zero pid.kp.limits.setlimit(10.0); asserteq!( pid.step(super::PidIn::new(measurement, time_delta)), super::PidOut::new(10.0, 30.0, 0.0, 40.0) );

let timedelta = 0.5; asserteq!( pid.step(super::PidIn::new(measurement, time_delta)), super::PidOut::new(10.0, 35.0, 0.0, 45.0) );

// setting upper limits returns error if new value conflicts with lower limit pid.ki.limits.trysetupper(28.0).unwrap();
asserteq!( pid.step(super::PidIn::new(measurement, timedelta)), super::PidOut::new(10.0, 28.0, 0.0, 38.0) );

// timedelta gets clamped to Float::epsilon() - Float::infinity() let measurement = 1.0; let timedelta = -7.0; pid.kd.setscale(numtraits::Float::epsilon()); asserteq!(pid.step( super::PidIn::new(measurement, timedelta)), super::PidOut::new(10.0, 28.0, -1.0, 37.0) );

// configure setpoint directly pid.setpoint = 1.0; asserteq!(pid.step( super::PidIn::new(measurement, timedelta)), super::PidOut::new(0.0, 28.0, 0.0, 28.0) ); ```

Contribute

Feel free to raise issues.

Would like to make #![no_std] optional so types can impl Display trait.