Abstract: An electrical system, such as a motor control system for a motorized wheelchair, includes a two-part electrical connector which connects a first sub-system to a second sub-system. A reference terminal of one part of the connector is connected to a voltage detecting circuit but is otherwise unconnected: in the event of the connector terminals corroding, a conductive path develops between the reference terminal and one of the other, active terminals and the voltage detecting circuit detects the resulting change in voltage at the reference terminal.

Abstract: A control system current (DC) motor in which driving signals are supplied to the stator windings of the motor in accordance with a measurement of the rotational speed of the motor and the position of the rotor of the motor. The speed measurement is obtained by combining a first signal representing the rotational speed of the motor derived from a measurement of the back-EMF developed in the stator windings of the motor and a second signal representing the rotational speed of the motor derived from the output of a sensor which senses the position of the rotor of the motor.