Design And Research Of Dissimilar Redundant Displacement Sensor

With the development of aerospace industry,servo actuator system has been widely used.Displacement sensor is an important component of actuator,and its reliable measurement plays a very important role in the performance of actuator.In this paper,LVDT and magnetic-grid-like measurement technology are taken as the starting point to carry out research on the key technologies of redundancy design of displacement sensor based on different principles.From theoretical model establishment to simulation analysis design,the sensor has the characteristics of tolerance to different failure mechanisms,which has important practical significance.The main research work of this paper is as follows:1)The theoretical model of non-similar redundant displacement sensor is established.Using magnetic field theory,mathematical models of LVDT and magnetic-grid measuring unit were established respectively,and parameters related to the output characteristics of the sensor were obtained,which provided theoretical support for the optimization of the structural parameters of the sensor.In order to realize the absolute measurement of magnetic-grid measuring unit,a coarse positioning coding method based on M sequence is proposed to realize the absolute measurement.2)The influence of structural parameters on output characteristics was quantitatively analyzed,and simulation analysis was carried out using Ansys Maxwell,such as the influence of coil turns,iron core size,ruler width and depth on output characteristics;At the same time,the influence of redundant structure on each measurement unit is analyzed and the feasibility of shielding structure is verified.3)Aiming at the nonlinear problem of LVDT output,the least square method and RBF neural network were used to correct it,and the results showed that the error of neural network correction was small;According to the characteristics of the response of Hall sensor,a preprocessing method of pulse interference filtering is proposed.According to the characteristics of induction signal of coarse positioning coding and fine positioning coding,the coarse positioning coding is analyzed by amplitude comparison method,and the fine positioning scale induction signal is subdivided by electronic subdivision method to improve the measurement accuracy.The CORDIC algorithm theory is used to realize the electronic subdivision which occupies less memory space.The adaptive weighted fusion algorithm is used to achieve the optimal output of the sensor.According to the above theories and methods,the sensor prototype was made,the calibration test platform was built,and the precision performance test,stability test and repeatability test were carried out.The test results show that the designed non-similar redundant displacement sensor can achieve a high measurement accuracy of 0.03 mm.