Abstract: Servo Control System (24) for positioning a load (35). A velocity drive signal (50), derived from a positional error signal, is provided by the outer loop (28) as the input to a velocity servo inner loop (26). The velocity drive signal is non-linear (48) and of the form V=.sqroot.2AD where A is the acceleration of the load and D is positional error (46).

Abstract: The disclosure describes an impact sensor having an electrical switch for actuation when an optical probe to which it is attached comes within a predetermined distance of an obstruction. An impact or contact element connected with the electrical switch sets the predetermined distance to actuate the switch. A resilient connector, such as piano wires, interconnect the contact element with the electrical switch, whereby the electrical switch is maintained in a non-actuation condition until the optical probe comes within the predetermined distance to the obstruction.