Research On Sensor Signal Processing For LOS Motion Control Of Airborne Photoelectric Platform

Airborne photoelectric platform is an important pay load for unmanned aerial vehicle and manned aircraft to perform tasks.It is always applied in disaster prevention and rescue,geographic mapping,precision agriculture and other fields.Gyro and accelerometer are the key sensors to construct the feedback loop of light of sight(LOS)control system of airborne photoelectric platform.However,due to the influence of drift,a large cumulative error exists in the attitude information obtained by the direct integration of the inertial angular velocity data measured by gyro.Accelerometers can also be used to measure angular attitude.However,due to the influence of maneuvering acceleration,there are also large errors in the inertial angular attitude measurement of practical application.It has an adverse impact on the control.In addition,it is necessary to process the sensor data in order to realize various control algorithms,such as PID control and signal differentiation.In order to obtain high precision attitude measurement signals and differential signals,it is necessary to process the sensor signals of LOS motion control of airborne photoelectric platform.This thesis focuses on sensor data differential processing and inertial attitude measurement.The following research are studied:(1)According to the performance requirements of small volume,low power consumption and fast operation speed of airborne photoelectric platform,the signal acquisition circuit of the actual system is designed.STM32F407IGH6 is used as the main control chip to carry out the software and hardware design of sensor measurement signal acquisition circuit and signal processing algorithm.The signal reading and processing of inertial measurement unit ICM20602 and encoder are realized,then the signal processing algorithm studied in this paper is verified.(2)The characteristics and applicable environment of quaternion method and Euler method are analyzed.The coordinate transformation of measurement vectors of gyro and accelerometer is studied.In order to compensate for gyro drift and maneuvering acceleration interference,an adaptive attitude algorithm based on multi-sensor data fusion is proposed.The adaptive threshold criterion is designed by accelerometer data to judge whether the influence of maneuver acceleration can be ignored.Based on this,the attitude is estimated by multi-sensor data fusion method and gyro drift modeling method,and a filter is designed to compensate the phase lag.The experimental results show that this method can effectively suppress the gyro drift and maneuver acceleration interference.It can solve the attitude in real time and accurately without obvious phase lag.(3)Sensor calibration compensation and the improvement of nonlinear tracking differentiator are carried out from the perspective of sensor data processing.Gyro and accelerometer are compensated by six position static calibration method.Experiments show that this method can effectively compensate the deterministic errors.In order to solve the difficulty of high-quality differential signal measurement in practical engineering,the nonlinear tracking differentiator is improved based on arctangent function and low-pass filter feedforward.The simulation results show that the improved method has good tracking and differential characteristics and certain filtering ability,and there is no obvious phase lag error.Based on the airborne photoelectric platform,a systematic method of inertial sensor measurement signal processing is proposed in this paper in order to solve the problems of gyro drift and maneuvering acceleration interference.The signal differentiation method proposed in this study can obtain more accurate tracking and differentiation signals with strong filtering ability.The experimental results show that the root mean square error(RMSE)of the proposed method is reduced by 32.27% and 22.97% respectively compared with the differential characteristics of the existing tracking differentiators based on power function and arctangent function.The attitude measurement method proposed in this study can obtain accurate attitude angle in real time under the interference of gyro drift and maneuvering acceleration.The experimental results show that the RMSE of the proposed method is reduced by 44.23%,49.91% and 46.21% respectively compared with the 3-axis angular attitude calculated by the gyroscope.The algorithm proposed in this thesis can improve the LOS stability control accuracy of airborne photoelectric platform from the perspective of signal processing.This method can meet the performance requirements of airborne photoelectric platform without introducing additional sensors and changing the mechanical structure.