147 lines
4.1 KiB
Rust
147 lines
4.1 KiB
Rust
use serde::{Serialize, Deserialize};
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#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
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pub struct Parameters {
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/// Gain coefficient for proportional term
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pub kp: f32,
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/// Gain coefficient for integral term
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pub ki: f32,
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/// Gain coefficient for derivative term
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pub kd: f32,
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/// Output limit minimum
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pub output_min: f32,
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/// Output limit maximum
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pub output_max: f32,
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}
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impl Default for Parameters {
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fn default() -> Self {
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Parameters {
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kp: 0.0,
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ki: 0.0,
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kd: 0.0,
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output_min: -2.0,
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output_max: 2.0,
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}
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}
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}
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#[derive(Clone)]
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pub struct Controller {
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pub parameters: Parameters,
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pub target : f64,
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u1 : f64,
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x1 : f64,
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x2 : f64,
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pub y1 : f64,
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}
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impl Controller {
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pub const fn new(parameters: Parameters) -> Controller {
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Controller {
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parameters: parameters,
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target : 0.0,
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u1 : 0.0,
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x1 : 0.0,
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x2 : 0.0,
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y1 : 0.0,
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}
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}
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// Based on https://hackmd.io/IACbwcOTSt6Adj3_F9bKuw PID implementation
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// Input x(t), target u(t), output y(t)
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// y0' = y1 - ki * u0
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// + x0 * (kp + ki + kd)
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// - x1 * (kp + 2kd)
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// + x2 * kd
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// + kp * (u0 - u1)
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// y0 = clip(y0', ymin, ymax)
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pub fn update(&mut self, input: f64) -> f64 {
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let mut output: f64 = self.y1 - self.target * f64::from(self.parameters.ki)
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+ input * f64::from(self.parameters.kp + self.parameters.ki + self.parameters.kd)
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- self.x1 * f64::from(self.parameters.kp + 2.0 * self.parameters.kd)
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+ self.x2 * f64::from(self.parameters.kd)
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+ f64::from(self.parameters.kp) * (self.target - self.u1);
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if output < self.parameters.output_min.into() {
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output = self.parameters.output_min.into();
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}
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if output > self.parameters.output_max.into() {
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output = self.parameters.output_max.into();
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}
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self.x2 = self.x1;
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self.x1 = input;
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self.u1 = self.target;
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self.y1 = output;
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output
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}
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pub fn summary(&self, channel: usize) -> Summary {
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Summary {
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channel,
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parameters: self.parameters.clone(),
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target: self.target,
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}
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}
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pub fn update_ki(&mut self, new_ki: f32) {
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self.parameters.ki = new_ki;
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}
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}
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#[derive(Clone, Serialize, Deserialize)]
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pub struct Summary {
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channel: usize,
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parameters: Parameters,
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target: f64,
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}
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#[cfg(test)]
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mod test {
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use super::*;
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const PARAMETERS: Parameters = Parameters {
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kp: 0.03,
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ki: 0.002,
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kd: 0.15,
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output_min: -10.0,
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output_max: 10.0,
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};
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#[test]
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fn test_controller() {
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// Initial and ambient temperature
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const DEFAULT: f64 = 20.0;
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// Target temperature
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const TARGET: f64 = 40.0;
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// Control tolerance
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const ERROR: f64 = 0.01;
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// System response delay
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const DELAY: usize = 10;
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// Heat lost
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const LOSS: f64 = 0.05;
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// Limit simulation cycle, reaching this limit before settling fails test
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const CYCLE_LIMIT: u32 = 1000;
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let mut pid = Controller::new(PARAMETERS.clone());
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pid.target = TARGET;
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let mut values = [DEFAULT; DELAY];
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let mut t = 0;
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let mut total_t = 0;
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let mut output: f64 = 0.0;
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let target = (TARGET - ERROR)..=(TARGET + ERROR);
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while !values.iter().all(|value| target.contains(value)) && total_t < CYCLE_LIMIT {
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let next_t = (t + 1) % DELAY;
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// Feed the oldest temperature
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output = pid.update(values[next_t]);
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// Overwrite oldest with previous temperature - output
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values[next_t] = values[t] - output - (values[t] - DEFAULT) * LOSS;
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t = next_t;
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total_t += 1;
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println!("{}", values[t].to_string());
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}
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assert_ne!(CYCLE_LIMIT, total_t);
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}
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}
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