| Aimed at the problem of the traditional herringbone structure of the crawler combine harvester chassis working in hilly mountains,undulating,soft and muddy environments,there are problems such as large body tilt angle,low harvest efficiency,poor driving comfort,and easy rollover accidents.A posture-controlled chassis of the tracked combine harvester was designed,which can adjust the ground clearance and tilt angle of the chassis online.The main contents and conclusions of this thesis are as follows:1)The principle of the chassis leveling system was analyzed,design the overall structure and leveling scheme of the posture-controlled chassis.The chassis structure was designed based on the four-point support platform,and the chassis body coordinate system was established to obtain the relationship between the distance from the four control points of the chassis to the horizontal plane and the inclination of the chassis from horizontal and longitudinal directional.Six basic combination actions were designed to meet the requirements of manual adjustment,and they are overall rise,overall fall,forward rise and back fall,forward fall and back rise,left rise and right fall,left fall and right rise.The automatic leveling scheme based on the four-point leveling principle was designed.2)The working principle of chassis lifting mechanism and hydraulic control system was analyzed,design and model selection key components.A chassis lifting mechanism based on a hinged five-bar mechanism was designed,and the lengths of the frame,the front arm,the rear arm,the link and the walking beam in the lifting mechanism are 880 mm,230 mm,230 mm,166 mm,947.63 mm,the theoretical motion angles are 0 °,9 ~ 46 °,180 ~ 212 °,270 ~ 290 °,-7 ~ 7 °.According to the structural parameters of the lifting mechanism,the track and the wheel system were designed and model selected.Design hydraulic control schematic diagram and determine the specific type of hydraulic components.3)The electronic control system for posture-controlled chassis was designed.Build the hardware circuit of the control system,mainly including the power management module,the minimum system of the single-chip microcomputer,the digital-to-analog conversion circuit,the solenoid valve drive circuit,the communication circuit,the storage circuit,and the input and output circuit.The inclination sensor data sending and receiving program,displacement sensor digital-to-analog conversion program,chassis manual adjustment,and automatic leveling program.The controller-related messages were designed based on the ISO11783 communication protocol.4)The electro-hydraulic co-simulation for posture-controlled chassis was carried out.Build a cosimulation system based on ADAMS and AMESim,and perform lifting simulation and leveling simulation.The lifting simulation shows that the longitudinal adjustment range of the chassis is-6.1 ~ 7.3 °,the lateral adjustment range is-6.9 ~ 6.9 °,and the ground clearance adjustment range is 0 ~ 129.9 mm.The leveling simulation shows that,compared with the traditional chassis,the maximum longitudinal inclination of the leveling chassis is reduced by about 68 % on the longitudinal slope of 10 °,and the maximum lateral inclination of the chassis is reduced by about 77.5 % when the lateral drop is 130 mm.5)The working performance of the posture-controlled chassis through prototype manufacturing and test analysis was tested.The prototype of the posture-controlled chassis was manufactured,the test evaluation index was designed,and the chassis performance was tested in laboratory and field.The static lift test shows that the longitudinal adjustment range of the chassis is-5.9 ~ 6.7 °,and the horizontal adjustment range is-6.1 ~ 6.9 °.The static leveling test shows that in 8 main directions,the chassis automatically adjusts in an average time of 4.2 s and the maximum steady-state error is 0.67 °.Field tests show that,relative to the non-leveling mode,the average chassis inclination in the auto-leveling mode is reduced by 83.1 %,57.1 %,and 82.9 %,and the standard deviation is reduced by 71.9 %,33.3 %,and 33.3 %;compared with the non-leveling mode In the manual leveling mode,the average chassis inclination is reduced by 61.9 %,38.1 %,and 42.3 %,and the standard deviation is not significantly improved. |
