Design Of Control Loop For Quartz Flexure Accelerometer Based On Model Identification

Quartz flexure accelerometer is a kind of high precision accelerometer in inertialtechnology. It should be combined with the rebalance loop when used to doacceleration measurement. A reasonably designed Rebalance loop necessarilyachieves different performance indicators to meet different application needs.In this paper, a control circuit of quartz flexure accelerometer based on modelidentification was designed. This method solved the problem of unknown parametersof traditional rebalance loop design process and inconvenience of parameteradjustment. It stated the Quartz flexure accelerometer closed-loop system’s workingprinciple, and found the main factors impacting acceleration measurement accuracy,then deeply analyzed the signal detection circuit, the analog part of the rebalanc e loopdesign. From a mechanical point of view, general type of quartz flexure accelerometerheader model was analyzed, then a model identification experiment was designed toachieve the parameter for the uncompensated open-loop system. The reliability of theidentification result was tested through lots of experiments. Three differentcompensation methods for system control was analyzed, then the optimal was choseto adjust the structure of quartz flexure accelerometer system. Simulation experimentwas developed to determine the controller parameters, the incremental PID controllerwas designed to real-timely adjust the loop bandwidth and stability margin of thequartz flexure accelerometer, as to compensate for negative effects to the performanceof the closed-loop system resulted from the header parameter changes.After the design of the control loop, series of experiments for testing andevaluating the system performance was undertook to further verify the validity andreliability of model identification results and controller design. Calibrationexperiments evaluated the system’s input and output relation. The effectiveness of thecircuit was proved by comparison with the given indicators of header manufacturers.Repetitive experiment was done in different conditions of the same input acceleration,and the stability experiment tested the stability of the scale factor and zero bias value.Finally, data analysis was done to determine the main factors affect the circuitperformance, and provided a necessary basis for the loop improvement.