M-Labs/thermostat
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pid: anti-windup when compliance voltage reached

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This commit is contained in:
topquark12 2021-01-11 14:00:52 +08:00
parent 3067b356c5
commit 193d54a0a6
3 changed files with 18 additions and 8 deletions
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6
src/channel_state.rs
View File

@ -3,11 +3,13 @@ use uom::si::{
f64::{
ElectricPotential,
ElectricalResistance,
ElectricCurrent,
ThermodynamicTemperature,
Time,
},
electric_potential::volt,
electrical_resistance::ohm,
// electric_current::ampere,
thermodynamic_temperature::degree_celsius,
time::millisecond,
};
@ -66,10 +68,10 @@ impl ChannelState {
}
/// Update PID state on ADC input, calculate new DAC output
pub fn update_pid(&mut self) -> Option<f64> {
pub fn update_pid(&mut self, current: ElectricCurrent) -> Option<f64> {
let temperature = self.get_temperature()?
.get::<degree_celsius>();
let pid_output = self.pid.update(temperature, self.get_adc_interval());
let pid_output = self.pid.update(temperature, self.get_adc_interval(), current);
Some(pid_output)
}

4
src/channels.rs
View File

@ -73,10 +73,10 @@ impl Channels {
pub fn poll_adc(&mut self, instant: Instant) -> Option<u8> {
self.adc.data_ready().unwrap().map(|channel| {
let data = self.adc.read_data().unwrap();
let current = self.get_tec_i(channel.into());
let state = self.channel_state(channel);
state.update(instant, data);
match state.update_pid() {
match state.update_pid(current) {
Some(pid_output) if state.pid_engaged => {
// Forward PID output to i_set DAC
self.set_i(channel.into(), ElectricCurrent::new::<ampere>(pid_output));

16
src/pid.rs
View File

@ -1,9 +1,13 @@
use serde::{Serialize, Deserialize};
use uom::si::{
f64::Time,
f64::{Time, ElectricCurrent},
time::second,
electric_current::ampere,
};
/// Allowable current error for integral accumulation
const CURRENT_ERROR_MAX: f64 = 0.1;
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct Parameters {
/// Gain coefficient for proportional term
@ -56,7 +60,7 @@ impl Controller {
}
}
pub fn update(&mut self, input: f64, time_delta: Time) -> f64 {
pub fn update(&mut self, input: f64, time_delta: Time, current: ElectricCurrent) -> f64 {
let time_delta = time_delta.get::<second>();
// error
@ -67,8 +71,12 @@ impl Controller {
// integral
if let Some(last_output_val) = self.last_output {
let electric_current_error = ElectricCurrent::new::<ampere>(last_output_val) - current;
// anti integral windup
if last_output_val < self.parameters.output_max.into() && last_output_val > self.parameters.output_min.into() {
if last_output_val < self.parameters.output_max.into() &&
last_output_val > self.parameters.output_min.into() &&
electric_current_error < ElectricCurrent::new::<ampere>(CURRENT_ERROR_MAX) &&
electric_current_error > -ElectricCurrent::new::<ampere>(CURRENT_ERROR_MAX) {
self.integral += error * time_delta;
}
}
@ -168,7 +176,7 @@ mod test {
while !values.iter().all(|value| target.contains(value)) && total_t < CYCLE_LIMIT {
let next_t = (t + 1) % DELAY;
// Feed the oldest temperature
let output = pid.update(values[next_t], Time::new::<second>(1.0));
let output = pid.update(values[next_t], Time::new::<second>(1.0), values[next_t]);
// Overwrite oldest with previous temperature - output
values[next_t] = values[t] + output - (values[t] - DEFAULT) * LOSS;
t = next_t;