Smoothing Jaw Via Websocket Client

Yes - the recommended ARC pattern is exactly what you described:

• WebSocket Client should only store the latest target amplitude
• A separate loop script should drive the jaw at a fixed rate
• Don’t move the servo directly inside the WebSocket Response Script

That is the clean, proven way to handle high-frequency input in ARC. If you try to animate the servo inside the WebSocket callback, you’ll get exactly what you’re seeing: chatter, lag, and dropped responsiveness.

Why your current approach jitters

Your WebSocket is sending 40-60 updates/sec, which means the Response Script is being fired constantly. If that script:

• reads servo position,
• computes easing,
• moves the servo,
• and especially if it sleeps,

then you’re mixing network reception with motion control. That causes timing conflicts and backlog.

Better architecture in ARC

1) WebSocket Client Response Script

Make it do only this:

• parse the amplitude
• save it to a global variable like $jaw_target

Example:

var amp = parseInt(getVar("$ws_amp", "0"));
if (isNaN(amp)) amp = 0;

setVar("$jaw_target", amp);

If you want to clamp it:

var amp = parseInt(getVar("$ws_amp", "0"));
if (isNaN(amp)) amp = 0;

if (amp < 0) amp = 0;
if (amp > 100) amp = 100;

setVar("$jaw_target", amp);

2) Separate jaw loop script

Run a loop script from a dedicated skill button, init script, or startup script. This script should:

• read $jaw_target
• read $lip_smooth
• smooth toward the target
• update D5 at a fixed rate like 25-30 Hz
• avoid blocking the WebSocket

Example JavaScript:

var jawPort = d5;
var minJaw = 40;
var maxJaw = 85;

while (true) {
  var amp = parseInt(getVar("$jaw_target", "0"));
  var smooth = parseInt(getVar("$lip_smooth", "5"));

  if (isNaN(amp)) amp = 0;
  if (isNaN(smooth) || smooth < 1) smooth = 1;

  if (amp < 0) amp = 0;
  if (amp > 100) amp = 100;

  var target = minJaw + ((amp / 100) * (maxJaw - minJaw));
  var current = Servo.getPosition(jawPort);

  if (current < 1) current = target;

  var next = current + ((target - current) / smooth);
  Servo.setPosition(jawPort, Math.round(next));

  sleep(33); // ~30 Hz
}

Important note

Your example uses GetServo(D5) and Servo(D5, next) - that’s not the preferred ARC approach. In ARC JavaScript, use the official API:

• Servo.getPosition(d5)
• Servo.setPosition(d5, value)

Also, don’t use Sleep(30) in a way that blocks the WebSocket response path. Use the separate loop instead.

Even better: add a deadband

To reduce chatter near small movements, only move the jaw if the difference is significant enough:

var jawPort = d5;
var minJaw = 40;
var maxJaw = 85;
var deadband = 1;

while (true) {
  var amp = parseInt(getVar("$jaw_target", "0"));
  var smooth = parseInt(getVar("$lip_smooth", "5"));

  if (isNaN(amp)) amp = 0;
  if (isNaN(smooth) || smooth < 1) smooth = 1;

  if (amp < 0) amp = 0;
  if (amp > 100) amp = 100;

  var target = minJaw + ((amp / 100) * (maxJaw - minJaw));
  var current = Servo.getPosition(jawPort);

  if (current < 1) current = target;

  var next = current + ((target - current) / smooth);

  if (Math.abs(next - current) >= deadband) {
    Servo.setPosition(jawPort, Math.round(next));
  }

  sleep(33);
}

Recommended ARC setup

WebSocket Client skill

• Response Variable: $ws_amp
• Response Script: update $jaw_target only

Slide Script skill

• Variable: $lip_smooth
• Range: 1 to 10
• Bonus button: set jaw to neutral or set $jaw_target to 0

Separate script skill

Use a script skill to continuously animate the jaw.

If you want it even cleaner

You can also have the WebSocket script write a latest target only, and let the loop script do all servo math. That keeps the WebSocket handler extremely lightweight.

On your neck servos

You’re right that D0/D1 are fine because they aren’t being hit at the same rate. But if you later want head movement to also follow streaming data, use the same pattern: latest target in one script, motion update in another.

Best practice summary

• Do not move servos directly in the WebSocket response
• Do not sleep inside the response script
• Store target values only
• Use a timed loop script to interpolate toward the target
• Use Slide Script for live smoothing control
• Add a deadband to stop micro-jitter

One more question

What do you want the jaw behavior to feel like overall:

• robotic and snappy
• natural speech-like movement
• or very smooth/cinematic

That changes the best update rate and smoothing math.

If you want, I can write you a complete ARC JavaScript solution using:

• WebSocket Client response script
• Slide Script integration
• jaw loop script
• neutral reset button