Proposal of accelerometer using zero-compliance mechanism

Accelerometer using zero-compliance mechanism is proposed. The zero-compliance mechanism is a series connection of a positive-stiffness suspension and a negative-stiffness suspension with the same amplitude of stiffness. In the proposed accelerometer, an inertial mass is suspended with this mechanism. Force acting on the inertial mass is proportional to the displacement of the connection point of two suspensions (detection point). The acceleration is given by dividing the force by the inertial mass. Therefore, the acceleration is estimated by the product of the displacement of the detection point and the amplitude of stiffness divided by the inertial mass. An experimental apparatus according to the principle is fabricated to study basic characteristics of the proposed accelerometer. To achieve the zero-compliance state, a voice coil motor is incorporated into the mechanism, and PID control is applied. In the experiment, static acceleration is given to the apparatus by gravity. The static acceleration measurement shows that the displacement of the detection point is proportional to the acceleration while the displacement of the point of force is virtually zero. A dynamic acceleration is also given to the apparatus. The measurement result shows that the acceleration estimated by the proposed method is almost same as that of a conventional servo-type accelerometer. These results demonstrate the feasibility of the acceleration measurement with a zero-compliance mechanism.