Research And Design Of The Hillside Crawler Tractor Attitude Leveling Control System

The terrain in the hilly areas is complicated and undulating.The stability of the crawler tractor in the hillside areas is closely related to the degree of the body attitude leveling.This paper takes the hillside crawler tractor developed by school of mechanical and electronic engineering in Northwest A&F University as the research object,and studies the hillside crawler tractor attitude leveling control system to improve the tractor’s stability and convenience of operation.The main contents of this research include:(1)The overall design plan of the hillside crawler tractor attitude leveling control system was determined.Combined with the research platform of hillside crawler tractors and the actual needs of tractors,the overall design and main hardware selection design of the attitude leveling control system of hillside crawler tractors was carried out,and related technologies involved in the control system including attitude calculation methods and Wi-Fi wireless network technology were briefly analyzed.(2)The information fusion filtering algorithm based on MEMS inertial sensors was studied.Firstly,the gyroscope and accelerometer of the inertial sensor MPU6050 were measured and corrected,and the preprocessing algorithms of the gyroscope and accelerometer were designed,implementing preliminary filtering of raw data from gyroscopes and accelerometers.Secondly,three filter algorithms based on conjugate gradient complementary filtering algorithm,quaternion-based extended kalman filter and Euler angle-based extended kalman filter were studied to perform fusion filtering on data of inertial sensor MPU6050,and the static test,vibration resistance test and dynamic response test were designed to compare and analyze the performance of the three filtering algorithms.The test results showed that the extended kalman filtering algorithm based on Euler angles performance best.In the static test,the average error of the attitude angle was reduced from0.04° before filtering to 0.01° after the filtering.In the dynamic test,the average error of the attitude angle was reduced from 0.96° before the filtering to 0.34° after the filtering.(3)The automatic leveling scheme design of the hillside crawler tractor was studied.Firstly,the principle of the body attitude adjustment of the hillside crawler tractor was analyzed,and the lateral limit attitude angle of the tractor was 15° and the longitudinal limit attitude angle was 8° by calculating.Secondly,based on the typical situation of tractor body tilt,the tractor’s automatic leveling strategy was proposed,and a mathematical model was set up for the tractor’s actuator.Finally,the fuzzy control was used to achieve the automatic leveling of the vehicle body,and the simulation analysis was performed on the MATLAB/Simulink software.The simulation results showed that the fuzzy control could better track the predetermined angular trajectory,and control effects were good.(4)The software and hardware integration and performance tests of the hillside crawler tractor’s attitude leveling control system were carried out.Firstly,the main software and hardware of the lower computer control system were designed,which the hardware design included power module circuit,serial communication module circuit,storage module circuit,relay module circuit design,and the software design includes storage module,serial communication module,other module designs;Then,the mobile phone APP interface was developed in the Android environment,and the design of the upper computer monitoring system was completed.Finally,the performance test of the attitude leveling control system was carried out.The test results showed that: when the hillside crawler tractor performed static automatic leveling on a flat ground to a steady state,the maximum error of its lateral attitude angle was 2.47°,and the maximum error of its longitudinal attitude angle was 2.68°;when performing dynamic automatic leveling on slopes,hillside crawler tractors ran at first gear speed(2.13 km / h).The lateral attitude angle of the body could be controlled within ±3.28 °,and the longitudinal attitude angle can be controlled within ± 2.73 °.The leveling process of the body was relatively stable,which could meet the operation demand.