let fast_jitter = [0.0, 0.0]; // init to zero

let slow_pointing = [0.0, 0.0]; // init to zero

let jitter_gain = 0.5;

let offload_fraction = 0.1;

let noise_std = 5.0;

let jitter_gain_slider, offload_fraction_slider, noise_std_slider;

​

function setup() {

  frameRate(30);

  createCanvas(400, 400);

  createDiv("Jitter Gain:");

  jitter_gain_slider = createSlider(0, 1, 0.5, 0.001);

  createDiv("Offload Fraction:");

  offload_fraction_slider = createSlider(0, 1, 0.1, 0.001);

  createDiv("Measurement Noise STD:");

  noise_std_slider = createSlider(0, 20, 0, 0.1);

  ellipseMode(CENTER);

}

​

function draw() {

  prep_display();

  read_sliders();

​

  let t = frameCount / 100;

​

  // true position: (bounded random walk)

  let pos = [];

  for (let p in [0,1]){

    pos.push(sf * (noise(t, p) - 0.5));

  }

  fill(255, 0, 0);

  ellipse(...pos, 20, 20);

​

  // noisy measurement: (additive gaussian noise, plus residual tip/tilt)

  let meas = [];

  for (let p in [0,1]) {

    meas.push(

      pos[p] - slow_pointing[p] - fast_jitter[p] + randomGaussian(0, noise_std)

    );

  }

  fill(0, 0, 255);

  noStroke();

  ellipse(...meas, 20, 20);

​

  // slow_pointing: (pure integral of offloaded jitter)

  for (let p in [0,1]) {

    slow_pointing[p] += offload_fraction * fast_jitter[p];

    fast_jitter[p] -= offload_fraction * fast_jitter[p];

  }

  stroke(0);

  strokeWeight(10);

  line(0, 0, ...slow_pointing);

​

  push();

  translate(...slow_pointing);

  // fast jitter: (pure integral of gain * measurement)

  for (let p in [0,1]) {

    fast_jitter[p] += jitter_gain * meas[p];

  }

  stroke(0);

  strokeWeight(5);

  line(0, 0, ...fast_jitter);

​

  // overkill plotting stuff:

  fill(255);

  ellipse(0, 0, 10, 10);

  ellipse(...fast_jitter, 10, 10);

  pop();

  strokeWeight(5);

  fill(255);

  ellipse(0, 0, 10, 10);

}

​

function prep_display() {

  background(220);

  noStroke();

  fill(0, 0, 255);

  ellipse(20, 20, 20, 20);

  fill(0);

  text("Closed-loop measurement", 35, 25);

​

  fill(255, 0, 0);

  ellipse(20, 43, 20, 20);

  fill(0);

  text("True disturbance", 35, 48);

​

  stroke(0);

  strokeWeight(10);

  line(width - 70, 20, width - 30, 20);

  noStroke();

  text("Pointing", width - 125, 23);

​

  stroke(0);

  strokeWeight(5);

  line(width - 70, 43, width - 30, 43);

  noStroke();

  text("Jitter mirror", width - 140, 47);

  translate(width / 2, height / 2);

  noStroke();

}

​

function read_sliders() {

  jitter_gain = jitter_gain_slider.value();

  offload_fraction = offload_fraction_slider.value();

  noise_std = noise_std_slider.value();

}

​