Signs and units

Robot code goes wrong most often when two parts disagree about which way is “positive”. This library uses ONE set of rules everywhere. Learn these and you can read any of it.

Driving

Value	Positive means	Where you see it
forward	robot moves forward	MecanumDrive.drive, TankDrive.arcade, the mixers
strafeRight	robot moves to its right (mecanum only)	MecanumDrive.drive, MecanumMixer.mix
turnClockwise	robot turns right (clockwise, seen from above)	same
IMU heading	robot turned left (counterclockwise)	ImuSetup.headingDeg, AutoDrive.turn, AutoDrive.turnTo, FieldPose.headingDeg
move(..., directionDeg, ...)	clockwise from forward: 0 forward, 90 right, 180 back, -90 left	AutoDrive.move, AutoDrive.moveWithTurn

Why is turning clockwise-positive but heading counterclockwise-positive?

• The right stick’s X is positive when pushed right, and pushing right should turn the robot right. So drive(forward, strafe, gamepad1.right_stick_x) just works.
• The FTC SDK’s IMU says heading grows when the robot turns left. That is the math rule (counterclockwise = positive) and we do not fight the SDK.

The names tell you which one you have: turnClockwise, headingCcwDeg (“CCW” = counterclockwise).

Gamepad sticks

The SDK gives negative left_stick_y when you push the stick UP (away from you). So “forward” is -gamepad1.left_stick_y. Every example in these docs has the minus sign.

Units

Thing	Unit
Distances (drive)	inches
Angles	degrees
Motor power	-1 to 1
Servo position	0 to 1
Mechanism positions (lifts, arms)	encoder ticks (counts)
Time	seconds, unless the name ends in Ms (milliseconds) or Nanos

Wheel order

Any array of four wheel values is in this order:

[front-left, front-right, back-left, back-right]

Standard (tank) drive left/right arrays are [left, right].

MecanumMixer.FRONT_LEFT (0), FRONT_RIGHT (1), BACK_LEFT (2), BACK_RIGHT (3) name the positions.