Driving Feels Wrong: Inversions, Drift, and Field-Relative Confusion

Symptom A — everything is backwards. Push forward, the robot reverses; turn left, it turns right. Cause: Xbox sticks report +1 toward the driver, so forward needs a negative sign; one missing negation flips an axis. Fix: Negate getLeftY() for forward and verify each axis independently on blocks: push forward -> robot drives away from you; push left -> strafes left. Change one sign, retest, repeat. Don't flip three signs at once or you'll chase your own tail.

Symptom B — the robot creeps when the sticks are centered. Cause: joysticks don't return to exactly 0.0; residual drift commands motion. Fix: apply a deadband. MathUtil.applyDeadband(value, 0.1) zeros out small inputs. DifferentialDrive applies 0.02 by default, but swerve code should add its own (0.05–0.10). If a stick drifts past your deadband, the controller hardware is worn — swap it; don't crank the deadband so high the robot feels numb.

Symptom C — field-relative points the wrong way after a bump or reboot. Cause: the gyro heading reference is wrong. Field-relative drive rotates joystick inputs by the gyro angle, so if zero isn't "downfield," everything is rotated. Fix: bind a gyro-reset button (driver.start().onTrue(drive.runOnce(drive::zeroHeading))) and press it while the robot faces directly downfield at match start. If heading drifts over a match, your gyro may need calibration time at boot (keep the robot still during robotInit) or a better-mounted IMU.

Diagnostic discipline: treat each of these as a one-variable experiment. Reproduce the symptom on blocks, form a specific hypothesis ("the Y axis sign is wrong"), make exactly one change, and re-test the same motion. Driving bugs feel mysterious because three small bugs at once produce chaos — but isolated, each one is trivial.

Prevent it: Write a 90-second pre-practice control check the drivers run every session: forward/back, left/right strafe, rotate both ways, slow mode, gyro reset facing downfield. If any axis is off, you catch it in the pit, not in a qualification match. The best drive teams treat the control scheme as flight-critical software and pre-flight it every single time.