Research On Measure System Of Six-axis Piezoelectric Accelerometer Based On Parallel Mechanism

The measurement of six-axis acceleration becomes increasingly necessary, with the trend ofaerospace, robotics, bio-medical and other fields towards the high precision and advanced direction.In view of the characteristics of parallel mechanism and piezoelectric ceramic, a measure system for apiezoelectric six-axis accelerometer, which is based on the9-SPS redundant parallel mechanism, wasdesigned to integrate of charge amplifier, signal acquisition and processing. Compared to traditionalmeasure system, this system not only has the advantages of low cost, small size and strong flexibility,but also reduces the distrurbance during the measurement, achieving the intelligent measurement.Firstly, the paper presented a deep and systematical analyzation about the state-of-arts researcheson six-axis accelerometer and measure system of piezoelectric sensors, and gave the content to bestudied in this paper. Based on the kinematics and dynamics model of the9-SPS redundant parallelmechanism, an acceleration decoupling algorithm was obtained. Then summarized the features of thepreamplifier circuits of the piezoelectric sensor, achieved sensor measurement diagram with9-SPSparallel piezoelectric accelerometer as an specific application object. The measure system was dividedinto charge amplifier module, signal acquisition and processing module. In contrast to the traditionalcharge amplifier, the charge amplifier module in this paper was improved by increasing the bufferstage and deleting the normalized stage. It can control the charge amplifier including the measurementrange, the filter parameters and gain automatically, with the advantages of small volume, highmeasure precision and ability to measure at a very low frequency. The signal acquisition andprocessing module was designed to sample and filter the output signal of charge amplifiers andcalculate the acceleration by means of the field programmable gate arrays and digital signalprocessors. The combination considered both execution speed and flexibility can ensure the ability tocalculate the acceleration real-timely. At the same time, it is easy to modify some parts of the programto measure other kinds of piezoelectric sensors. Finally, the performance of the measure system wasverified by experimental analysis.The measure system designed in this paper can achieve real-time measurement, display and savethe results automatically, thus, it has a high value in application.