If the left‑hand switch is released, the Program is inhibited and the Grounding Plate is freed. The servo holds the last commanded steer angle between vehicle and Sprint handwheels. With release of the right‑hand switch, the system is de-energized: the Grounding Plate is freed and the motor fail‑safe brake locks the motor position, restoring full manual control. Releasing either or both switches produces the same driving condition.
It is important from a human factors standpoint that the driver's hands remain on the handwheel. This feature is made possible by use of a "Series Servo", in which the Machine adds to the rotation of the Sprint Handwheel. During programmed steer the vehicle steering wheel rotates while the Sprint handwheel remained "grounded" to the vehicle windshield. During violent maneuvers the driver's hands remain on the stationary Sprint handwheel, for body support and machine control. In our competition's steering robots, the handwheel spins: in violent maneuvers the driver must avoid contact with the spinning handwheel while "hanging on" to a joystick or stop switch along with the door panel.