Research On Noise Suppression Method Of Control Loop Used In Closed Loop Sensor

The control loop noise is the main factor that affects the noise performance of the closed-loop sensor and has an important influence on the measurement accuracy of the closed-loop sensor.It is very difficult to improve the noise performance of closed-loop sensor from the point of view of noise source,which leads to the bottleneck of improving the accuracy of closed-loop sensor.In order to reduce the noise of the closed-loop sensor and lay a foundation for further improving the accuracy of the closed-loop sensor,this paper deeply studies the noise shaping mechanism of the control loop and proposes to optimize the noise transfer path of the control loop.The main contents of this paper are as follows:(1)The control loop noise shaping mechanism of closed-loop sensor is studied.By analyzing the transfer function of detection noise and driving noise in the control loop,the spectrum characteristics of detection noise and driving noise after passing through the closed loop and the key factors affecting the spectrum characteristics are obtained,and the control loop noise shaping model of closed-loop sensor is established.In order to verify the model,a prototype of acceleration closed-loop sensor is developed.The control loop noise and closed-loop sensor noise of the prototype are tested separately,and the results are compared with the prediction results of the model.The experimental results are in good agreement with the prediction results,which proves the efficiency of the control loop noise shaping model of closed-loop sensor.(2)The optimization method of control loop noise transfer path in closed-loop sensor is studied.Based on the control loop noise shaping model of closed-loop sensor,the optimization method and effect of each key factor are studied through theoretical analysis and simulation verification,aiming at the five key factors:swing of sensitive structure,gain of detection structure,gain of detection module,bending stiffness of sensitive structure and integral coefficient of control module.The acceleration closed-loop sensor prototype is improved by the proposed optimization method.The standard deviation of noise in the 100 Hz bandwidth of the prototype is 11.8 ?g,which proves the effectiveness of the optimization method(3)The data fusion algorithm of low drift closed-loop sensor and high dynamic sensor is studied.Through combining different sampling frequency and noise complementary sensors,the data fusion algorithm is studied,so that the combination scheme has low drift and high dynamic measurement ability.The experimental device combining the quartz flexible accelerometer and the piezoelectric accelerometer is designed to make the drift of the piezoelectric accelerometer converge to the level of the quartz flexible accelerometer,which proves the validity of the data fusion algorithm.(4)The parameter identification method of the closed-loop sensor with time delay is studied.The time-delay identification method based on the monotonic number of time series is studied,which makes the time-delay identification robust to the measurement noise.Then,the parameters of the controlled loop are identified based on the least square method.In this paper,the method is used to test the quartz flexible accelerometer,and the time delay in the controlled loop of the quartz flexible accelerometer is confirmed.