RoboMat Simulator

Ready

Reset to Base on Run Show ultrasonic ray 10 cm grid Real-world noise Drive by hand: ↑↓←→ when no program is running

Gyro heading

0°

total turned 0°

Ultrasonic

---

Color sensor

white

reflected light 0%

Left motor

0°

power 0% · tacho

Right motor

0°

power 0% · tacho

Position x, y (cm)

0, 0

sim time 0.0 s

JavaScript with the same commands as the blocks. Robot commands take time, so put await in front of them. In your own loops, always await tick().

The robot

A two-wheel differential-drive robot (40 × 40 px ≈ 12 × 12 cm) with a free caster at the back. The color sensor looks down from the front bumper, and the ultrasonic sensor looks straight ahead (range 45 cm). The field is 240 × 120 cm, and 1 px = 0.3 cm.

Real-world noise makes the right motor about 3 % weaker, adds gyro drift and sensor jitter. drive(), driveUntilColor() and line following correct for it. Raw setMotors() and startDriving() don't, so watch the robot curve.

Speeds are motor power from −100 to 100 %. Angles are degrees, and right turns are positive. The gyro reads 0° in the direction the robot faced at the start.

Movement (await these)

`drive(cm, speed=50)`	Drive straight using the wheel encoders. Negative cm drives backward.
`turn(deg, speed=30)`	Spin in place using the gyro. Positive = right, negative = left.
`turnTo(heading)`	Turn to an absolute gyro heading.
`driveUntilColor(c, speed=40)`	Drive straight until the color sensor sees color `c`.
`wait(seconds)`	Do nothing for a while (the motors keep doing what they were doing).

Line following (await these)

`followLineUntilDistance(cm, speed=35, edge='left')`	Follow the black line's edge until the ultrasonic reads less than `cm`.
`followLineUntilColor(c, speed=35, edge='left')`	Follow the line until the sensor sees color `c` (not black or white).
`followLineFor(cm, speed=35, edge='left')`	Follow the line for a distance.

Motors (instant)

`startDriving(speed, steer=0)`	Start moving and keep going. Steer −100…100: 50 pivots on one wheel, 100 spins in place.
`setMotors(left, right)`	Set each wheel's power directly.
`stop()`	Brake both motors.

Waiting for sensors (await these)

`waitUntilColor(c)`	Wait until the color sensor sees `c`.
`waitUntilDistance(cm)`	Wait until the ultrasonic reads less than `cm`.
`tick()`	Wait one simulation step (5 ms). Use it inside every loop you write.

Sensors (instant)

`color()`	`'black' 'white' 'red' 'green' 'blue' 'yellow'` or `'none'`
`reflected()`	Reflected light 0–100 % (black ≈ 8, white ≈ 96)
`rgb()`	`[r, g, b]` under the sensor, 0–255
`distance()`	Ultrasonic distance in cm, or `Infinity` when nothing is in range
`heading()`	Gyro heading, −180…180°
`angle()`	Total degrees turned since the last reset (keeps counting past 360)
`leftTacho()`, `rightTacho()`	Wheel encoder degrees
`resetGyro()`, `resetTachos()`	Zero the gyro or the encoders
`time()`	Simulated seconds since Run
`log(...values)`	Print to the console below

Example: your own line follower

setMotors(30, 30);
await waitUntilColor('black');
while (distance() > 20) {
  const error = reflected() - 50;   // + on white
  setMotors(30 + error * 0.6, 30 - error * 0.6);
  await tick();                      // let time pass!
}
stop();

Console