Research On Active Attitude Adjustment System Of Tractors In Hilly Mountains

Agricultural machinery equipment is one of the ten key areas of development proposed in "Made in China 2025".The acceleration of modern agricultural construction process and the improvement of market competitiveness of agricultural products depend on the development of agricultural machinery equipment.The autonomous attitude adjustment technology of tractor in hilly area is an important part of the intelligent research of agricultural machinery equipment.In this paper,based on the traditional wheeled torsional tractor for hills and mountains,the active attitude adjustment system is realized,and the control system,active attitude adjustment control algorithm and vehicle management system are studied in depth.The main research contents are as follows:(1)The active attitude adjustment system of tractor is realized.In view of the structural characteristics of the existing wheeled torsional tractor for hills and mountains and the drawbacks of heavy weight and lack of attitude adjustment function,the active attitude adjustment system is designed.To meet the needs of active attitude adjustment,it includes the active attitude adjustment mechanism,hydraulic drive system and control system.(2)The hardware of the main controller is designed,the working principle and driving technology of electro-hydraulic proportional valve are studied.In view of the problem that the "dead zone" of the electro-hydraulic proportional valve will reduce the stability of the control system,a method to overcome the "dead zone" by using the low-frequency PWM self-contained parasitic chatter is proposed.According to the functional requirements of the main controller,the problems of component selection and hardware circuit design of the core module of the main controller are solved.(3)According to the working condition and active attitude adjustment demand of hilly tractor,the control algorithm of active attitude adjustment system is studied,and the swing angle control algorithm of the swing mechanism based on PID control algorithm and fuzzy PID control algorithm is proposed respectively,as well as the vehicle body horizontal leveling control algorithm based on double closed-loop PID control algorithm and double closed-loop fuzzy PID control algorithm.The experimental results show that the dynamic response performance of the double closed-loop fuzzy PID control algorithm is better.When the tractor is running at a speed of 5km/h in the real farming environment of hills and mountains,the inclination angle of the tractor body can be controlled within±1° and the absolute value difference of the swing angle of the swing mechanism is within ±2°.In the bad working environment,the inclination angle of the tractor body can be controlled within ±3° and the absolute value difference of the swing angle of the swing mechanism is within ± 5°,which meet the requirements of the operation in hilly and mountainous areas.(4)According to the user’s requirements to the tractor in hilly area of attitude adjustment control,running state monitoring,debugging algorithm control performance and so on,the vehicle management system is realized.The communication architecture between the vehicle management system and the main controller,tractor ECU,sensor system is studied,and a reliable communication management mechanism is designed.The functions of the working mode and debugging mode of the vehicle management system are realized.