12 / Driver Control

Driver Control

Turn gamepad input into predictable mecanum movement.

60 minCoreDriver Control

You will

01Read joystick axes correctly.
02Combine drive, strafe, and turn values.
03Normalize motor powers before writing to hardware.

Why Driver Control matters

This lesson is about the interface between drivers and robot behavior. Good TeleOp code is not just mathematically correct; it is predictable under pressure, easy to recover, and readable enough that the drive team can describe what the robot is supposed to do.

Starting point

Driver code should feel boring

A driver should not need to understand your math during a match. Good TeleOp code makes common movement predictable and keeps surprises out of competition.

Normalize before sending power

Mecanum formulas can produce values above 1.0. Normalizing keeps the ratio between wheels while staying inside the legal motor power range.

Build path

Test driver code in movement primitives and mechanism primitives instead of full-match chaos. Add deadbands, slow modes, edge detection, and safe states only after students can explain the raw input and final output for each control.

For this specific lesson, students should first restate the goal in robot terms, then identify the value or behavior they expect to observe, then run the smallest test that proves the idea. The lesson should feel like a guided lab: predict, run, observe, explain, and only then extend.

MecanumTeleOp.java · Java

double drive = -gamepad1.left_stick_y;
double strafe = gamepad1.left_stick_x;
double turn = gamepad1.right_stick_x;

double fl = drive + strafe + turn;
double fr = drive - strafe - turn;
double bl = drive - strafe + turn;
double br = drive + strafe - turn;

double max = Math.max(1.0, Math.max(
  Math.max(Math.abs(fl), Math.abs(fr)),
  Math.max(Math.abs(bl), Math.abs(br))
));

frontLeft.setPower(fl / max);
frontRight.setPower(fr / max);
backLeft.setPower(bl / max);
backRight.setPower(br / max);

Debugging and failure modes

When TeleOp feels wrong, translate driver feedback into small tests: forward, strafe, rotate, precision mode, button press, held button, and safe recovery. Print raw inputs and final commands so the team can separate driver feel from wiring, math, and mechanism bugs.

Checks

Forward on the stick moves the robot forward.
Strafe does not rotate the robot badly.
No motor receives power outside -1.0 to 1.0.

Check your understanding

Module check

What should you check first when robot code does not behave as expected?

0 of 1 answered

References

FIRST FTC DocsOfficial FTC SDK and robot programming documentation.Learn Road RunnerFTC autonomous and trajectory reference.