Design And Simulation Of Track Chassis And Active Levelling Device In Hilly Region

Most cultivated areas in southern China are located in hilly and mountainous areas.Hilly and mountainous terrain is complex and the slope varies greatly.The complex environment makes the agricultural mechanization rate in hilly areas low.Now,hilly mountain orchard in plant protection and picking still rely on manual labor.At present,there is a lack of agricultural machinery suitable for complex terrain in China,so it is very important to study a carrier chassis which can work stably in hilly areas.Based on the analysis of the structure and principle of the mountain carrier chassis mechanism at home and abroad,the track structure is widely used in hilly areas for its better transmissibility and adaptability to the environment.In this paper,combined with the characteristics of the track structure,in order to reduce the risk of backflip and rollover of the track chassis in the working process,a device capable of active leveling is designed,which can effectively improve the running stability of the track chassis.The research content is as follows:(1)Design of mechanical structure.By reading literature,the research trend and progress of crawler chassis and active leveling mechanism at home and abroad are analyzed,and the main structure of crawler chassis and leveling mechanism is designed in combination with the actual demand.The main research content is to control the leveling mechanism to reduce track rollover,and the corresponding technical route is formulated.It focuses on the structure design of the four wheel belt of the track chassis and the active leveling.At the same time,it selects the steering mechanism and the power mechanism.(2)Dynamic modeling of track chassis and active levelling device.The dynamics model of the crawler chassis and the active levelling device is established,and the relationship between the tilting Angle of the levelling device and the expansion length of the end actuator as well as the force relationship between the crawler chassis and the ground is analyzed.The lateral load transfer rate(LLTR)is used as the evaluation index of vehicle stability according to the change of vertical load of left and right track.The feasibility of the model is verified by establishing a virtual prototype in Recur Dyn.(3)Design of control system.The corresponding control strategy is developed according to the nonlinearity,uncertainty and time-varying parameters in the track chassis operation process.Fuzzy control principle is added on the basis of PID algorithm.By comparing the control characteristics of the two algorithms,fuzzy PID is selected as the control algorithm of the active levelling device.Through the co-simulation of Matlab/Simulink and Recur Dyn and the fuzzy PID control algorithm,the simulation results of the model in three road conditions were analyzed,and it was concluded that the active leveling device can enhance the stability of the track chassis.(4)The construction of the prototype.The prototype of track chassis and active levelling device was built,and the effectiveness of active levelling device was judged by analyzing the motion results of active levelling device on different slopes.The results show that the motion error of the active leveling device will increase with the increase of slope,but all are within the allowable error range,which proves the effectiveness and accuracy of the device on slope.