Electrically driven invalid chair - uses voltage derived from current through motor to represent its speed

摘要

The vehicle, particularly an electric chair, is driven by a direct-current motor, there being a control circuit to keep motor speed at a selected value and the current to the motor regulated dependent on the difference. The signal representing motor speed is a voltage derived from the current through it. The control circuit can have a feedback such that its initial impedance is equal in value to that of the motor, but negative.