Identification and adjustment of the position and attitude for the electrostatic accelerometer's proof mass

Abstract In an electrostatic force feedback accelerometer (EFFA 1 ) system, nonlinearities in the transfer function between the input acceleration and the output voltage signal are mainly brought in by the detection circuit, demodulation circuit, and unsatisfactory closed-loop position of the proof mass. Closed-loop control can overcome the first two effect factors but remains ineffective to the last. The traditional way to adjust the closed-loop position is rolling the EFFA on the turntable, and then experientially adjusting according to the output feedback voltages to make the proof mass gradually approach the ideal closed-loop position by repeated times. This paper proposes a novel method which can simplify the complex process and save the turntable. According to the feedback voltages changing with the varying preload-voltage, the relative closed-loop position of the proof mass can be calculated and the proof mass can be adjusted to any required positions including the ideal one. The whole test process turns to be automatical and quantitative by using digital controllers such as DSP. Applying this novel way to the electrostatic levitation accelerometer which cannot be placed on the turntable because of its extremely low range, the problem of position adjustment can be solved.