An electromechanical chest compressor is provided with a reciprocating member for contacting a patients chest the reciprocating member extends from and retracts into a housing positioned on a patients chest maintained in contact with a patient by a circumscribing thoracic cavity belt. The reciprocating member is driven by a follower in contact with a rotating drive screw. The drive screw is mounted coaxially with and internally of a permanent magnet DC motor and is connected to the motors rotor. The current supplied to each of the individual stator windings of the motor is independently controlled by a control system that accesses addresses in a look-up table to determine the value of the current to be supplied to the individual windings.
