Abstract: A piezoelectric flexible arm member is mounted to a base at one end and supports a torque coil in a magnetic field at its other end. The torque coil comprises a seismic element disposed to be moved in accordance with acceleration forces applied thereto. A voltage is produced across the piezoelectric flexure arm when movement of the torque coil causes it to flex. The torque coil may include means to induce a signal in a position detector circuit representative of the position thereof. Both the signals from the piezoelectric member and the position detector may be used as error signals in a servo amplifier system to provide restoring forces to the torque coil and to produce an output signal representative of acceleration forces. A third conventional error signal may also be employed in the system.

Abstract: A servo amplifier system for an accelerometer includes a torque coil. A torque coil is included in the output circuit of a first amplifier. A position sensor circuit develops a signal corresponding to the position of the coil which is applied to the input circuit of the first amplifier. An element, which may be a resistor, senses the current through to the coil and produces a voltage which is applied to a second amplifier having a low impedance output circuit. The output signal from the second amplifier is fed back to the input circuit of the first amplifier. Means are associated with the second amplifier to comply with the scaling and bandwidth requirements of the system.