README
¶
PID Controller
A PIDController implementation in Go.
Credits
Initially done by Felix Geisendörfer (felix@debuggable.com)
Refer to his original: https://github.com/felixge/pidctrl
Documentation
¶
Overview ¶
Package pidctl implements a proportional–integral–derivative (PID) controller using rational numbers. Refer to https://en.wikipedia.org/wiki/PID_controller.
Example ¶
A car whose PID controller is going to act to try to stabilize its speed to the given setpoint.
package main
import (
"fmt"
"math"
"math/big"
"time"
"cirello.io/pidctl"
)
func main() {
car := pidctl.Controller{
P: big.NewRat(1, 5),
I: big.NewRat(1, 100),
D: big.NewRat(1, 15),
Min: big.NewRat(-1, 2), // min acceleration rate: 0.5 mps
Max: big.NewRat(10, 2), // max acceleration rate: 5 mps
Setpoint: big.NewRat(60, 1), // target speed: 60 mph
}
speed := float64(20) // the car starts in motion. 20mph
const travel = 15 * time.Second
for i := time.Second; i <= travel; i += time.Second {
desiredThrottle := car.Compute(new(big.Rat).SetFloat64(speed))
actualThrottle, _ := desiredThrottle.Float64()
actualThrottle = math.Ceil(actualThrottle)
fmt.Printf("%s speed: %.2f throttle: %.2f (desired: %s)\n", i, speed, actualThrottle, desiredThrottle.FloatString(2))
speed += actualThrottle
switch i % 5 {
case 0:
// head wind starts strong: 2mps
speed -= 2
case 1:
// head wind ends weak: 1mps
speed -= 1
}
}
}
Output: 1s speed: 20.00 throttle: 5.00 (desired: 5.00) 2s speed: 23.00 throttle: 5.00 (desired: 5.00) 3s speed: 26.00 throttle: 5.00 (desired: 5.00) 4s speed: 29.00 throttle: 5.00 (desired: 5.00) 5s speed: 32.00 throttle: 5.00 (desired: 5.00) 6s speed: 35.00 throttle: 5.00 (desired: 5.00) 7s speed: 38.00 throttle: 5.00 (desired: 5.00) 8s speed: 41.00 throttle: 5.00 (desired: 5.00) 9s speed: 44.00 throttle: 5.00 (desired: 5.00) 10s speed: 47.00 throttle: 5.00 (desired: 5.00) 11s speed: 50.00 throttle: 5.00 (desired: 4.55) 12s speed: 53.00 throttle: 5.00 (desired: 4.02) 13s speed: 56.00 throttle: 4.00 (desired: 3.46) 14s speed: 58.00 throttle: 4.00 (desired: 3.15) 15s speed: 60.00 throttle: 3.00 (desired: 2.75)
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Controller ¶
type Controller struct {
// P is the proportional gain
P *big.Rat
// I is integral reset
I *big.Rat
// D is the derivative term
D *big.Rat
// Setpoint is the chased target
Setpoint *big.Rat
// Min the lowest value acceptable for the Output
Min *big.Rat
// Max the highest value acceptable for the Output
Max *big.Rat
// contains filtered or unexported fields
}
Controller implements a PID controller.
func (*Controller) Accumulate ¶
Accumulate updates the controller with the given process value and duration since the last update. It returns the new output that should be used by the device to reach the desired set point.
func (*Controller) Compute ¶
func (p *Controller) Compute(pv *big.Rat) *big.Rat
Accumulate updates the controller with the given process value since the last update. It returns the new output that should be used by the device to reach the desired set point. Internally it assumes the duration between calls is constant.
Source Files