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Node.js PID controller


Simple Node.js PID controller.

$ npm install node-pid-controller

Let's take the example of a car cruise control. We want the car driving at 120km/h.

k_p, k_i and k_d are the proportional, integral and derivative terms. dt is the interval of time between two measures. If not set, it will be automatically calculated.

let Controller = require('node-pid-controller');
let ctr = new Controller({
  k_p: 0.25,
  k_i: 0.01,
  k_d: 0.01,
  dt: 1

You can also pass options as arguments:

let ctr = new Controller(0.25, 0.01, 0.01, 1); // k_p, k_i, k_d, dt 
ctr.setTarget(120); // 120km/h 
let correction = ctr.update(110); // 110km/h is the current speed 

Normally, you use the correction to a measure, in a closed loop.

let goalReached = false
while (!goalReached) {
  let output = measureFromSomeSensor();
  let input  = ctr.update(output);
  goalReached = (input === 0) ? true : false; // in the case of continuous control, you let this letiable 'false' 
  • k_p, k_i, k_d: the PID's coefficients
  • dt: interval of time (in seconds) between two measures. If not provided, it will be automatically calculated.
  • i_max: the maximum absolute value of the integral term (optional)
mocha test

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