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Robot PU Follows the Leader

Here’s a clean, practical example showing multiple Robot PU robots acting as followers, all controlled by one gamepad robot that broadcasts:

Compass heading → direction Joystick Y → speed Every follower receives the radio message, extracts the heading + speed, and drives accordingly.

This pattern scales to any number of robots.

🕹️ Leader Robot (Gamepad Controller)​

The leader reads:

  • Compass heading using input.compassHeading()
  • Joystick speed using robotPu.joystickY() (or your own joystick input)

Then it broadcasts both values in a single radio packet.

// Leader (Gamepad) Robot
radio.setGroup(42)

basic.forever(function () {
    // Compass heading: 0–359 degrees
    let heading = input.compassHeading()

    // Joystick Y: -100 to +100 (forward/backward)
    let speed = robotPu.joystickY()

    // Pack into a string: "heading,speed"
    let msg = heading + "," + speed

    radio.sendString(msg)
    basic.pause(80)
})

The leader does not move — it only broadcasts control signals.

🤖 Follower Robots (All Other Robots)​

Each follower robot:

  1. Receives "heading,speed"
  2. Parses the two numbers
  3. Converts heading into a turn value
  4. Converts speed into a forward velocity
  5. Drives toward the leader's heading

📡 Step 1 — Radio Setup​

radio.setGroup(42)

All robots must use the same group.

📨 Step 2 — Receive and Parse Messages​

let targetHeading = 0
let targetSpeed = 0

radio.onReceivedString(function (msg) {
    let parts = msg.split(",")
    targetHeading = parseInt(parts[0])
    targetSpeed = parseInt(parts[1])
})

🧭 Step 3 — Heading Error → Turn Command​

Followers compare:

leader heading – my heading

This gives a heading error that we convert into a turn value.

function headingError(): number {
    let myHeading = input.compassHeading()
    let error = targetHeading - myHeading

    // Wrap error to [-180, +180]
    if (error > 180) error -= 360
    if (error < -180) error += 360

    return error
}

🚗 Step 4 — Convert Error → Turn Amount​

function computeTurn(): number {
    let err = headingError()

    // Scale error to turn value (-1 to +1)
    let turn = err / 90
    if (turn > 1) turn = 1
    if (turn < -1) turn = -1

    return turn
}

🏎️ Step 5 — Convert Joystick Speed → Forward Speed​

function computeSpeed(): number {
    // joystick Y is -100..100 → convert to -2..2
    return targetSpeed / 50
}

🔁 Step 6 — Main Follower Loop​

basic.forever(function () {
    let fwd = computeSpeed()
    let turn = computeTurn()

    robotPu.walk(fwd, turn)
    basic.pause(20)
})

🎉 What You Now Have​

With this setup:

  • The leader robot acts like a wireless gamepad
  • All followers align themselves to the leader's compass heading
  • Joystick Y controls speed
  • Heading controls direction
  • The swarm stays synchronized
  • Any number of followers can join

This is the foundation for:

  • leader‑follower swarms
  • formation control
  • synchronized robot movement
  • remote teleoperation of multiple robots

You can extend this into:

  • V‑formation swarm
  • Boids flocking behavior
  • Obstacle‑avoiding followers
  • Leader handoff (dynamic leadership)