Patent ID: RE39581

Claim:
An apparatus for use on a surface and responsive to an operator, said apparatus comprising: a vehicle adapted to ride on the surface; a head assembly adapted to carry a device for engaging and treating the surface; a support; a connector assembly interconnecting the head assembly and the support; an actuator on the vehicle for raising and lowering the support relative to the surface; a sensor detecting a distance between the support and the head assembly; a head position control, responsive to input from the operator, indicating a desired position of the head assembly relative to the support; and a driving circuit responsive to the head position control and responsive to the sensor for energizing the actuator to raise and lower the support so that the distance between the support and the head assembly as detected by the sensor corresponds to the desired position as indicated by the head position control thereby controlling the relative engagement between the head assembly and the surface and thereby controlling the treatment of the surface by the head assembly.