Analysis And Experimental Study On The Running Performance Of The Small Crawler Chassis For Mountain On Slope

Rubber track chassis has the advantages of low specific ground pressure,flexible steering and strong off-road capability,and it is a preferred option for power chassis of agricultural machinery in Hilly and mountainous areas.In view of the special working environment in Hilly and mountainous areas which seriously affects the driving performance of track chassis,at present,the trafficable test of track chassis mainly relies on road test method,requiring professional test site,which has problems such as high cost,poor repeatability and great limitations,so it is not convenient to assess the driving characteristics of track chassis.Therefore,it is of great theoretical significance and demand background to carry out the research on the slope driving performance of track chassis by combining theoretical analysis and experimental research.This paper takes a small mountainous track chassis independently developed as the object,combines the topographic and geomorphic characteristics of Hilly and mountainous areas,through theoretical analysis,simulation analysis and real-vehicle test,explores the main factors influencing the dynamic characteristics of its sloping land,such as trafficability,steering and stability,and comprehensively evaluates its sloping driving performance.The main research work of this paper is:1.The dynamic model of the track chassis traveling on the soft slope road surface with a slope angle of 25 degrees was established,and the influence of slope angle,offset angle and soil environment on the key parameters such as support force,ground pressure and traction was analyzed.The results show that the slope angle and offset angle affect the distribution of ground pressure of the track chassis,which further affects its traction and motion state.Under the same soil environment,the driving force required by the track chassis on the road with different slope angles is relatively close.And the trafficability evaluation index of the test track chassis on the soft road with 25 degrees slope angle is more than 0.268,which can operate normally.2.The model of crawler chassis crossing vertical obstacles and trenches on slope was established,and the influence of slope angle and center of gravity position on ultimate obstacle-crossing height and width of ultimate trench was analyzed.The results show that the ability to cross vertical obstacles such as steps is stronger when the center of gravity of the track chassis is forward or down.The ability to cross ditches is stronger when the center of gravity is positioned centrally or down.The limit overcoming height of the self-made track chassis is about 250 mm,and the limit width of the ditches that can be crossed when the slope angle is 0,5,10,15,20 and 25 degrees is 538 mm,516mm,494 mm,471mm,447 mm,422mm,strong ability to cross obstacles.3.Considering centrifugal force,sliding between track and ground,a steering model in soft slope pavement environment of track chassis was established,and the influence of main factors such as slope angle,steering radius,steering angle and soil environment on steering performance of track chassis slope was analyzed.The results show that with the increase of the slope angle,the key parameters such as traction,braking force,steering drive torque and resistance torque will increase.With the increase of steering radius,the above key parameters will decrease.With the steering angle at [0,360)degrees,all of the above key parameters change periodically,usually increasing on uphill slope and decreasing on downhill slope.Soil environment has a greater influence on the steering performance of the slope land of the track chassis.4.Discussed the stability of track chassis slope during straight driving and steering movement,and analyzed the influence of main factors such as slope angle,steering radius,steering angle and soil environment on the steering stability of track chassis slope.The results show that the larger the slope angle,the smaller the steering radius and the larger the slip rate.In the case of slower speed,the steering angle has a significant influence on the longitudinal offset by soil environment and slope angle.The largest longitudinal offset occurs at the steering angle of 90 and 270 respectively.The longitudinal and transverse ultimate tilt angles of the track chassis for test are 65 and 60 respectively,which have a good stability.5.Based on RecurDyn,the multi-body dynamic model of the test track chassis was established.And the validity of that model was verified by combining the vehicle test and simulation analysis,as well as the correctness of the theoretical analysis of the above-mentioned track chassis slope trafficability,steering and stability.The results show that the average driving speed and driving wheel torque of the track chassis have good consistency in straight driving on soft road surface with a relative error of less than 3%,which indicates that the multi-body dynamic model of the track chassis established is effective.The driving performance of the track chassis obtained by different analysis methods is better consistent in straight driving and steering on soft slope road surface.Property,which indicates that the established kinematic model of driving and steering on soft slope road surface of tracked vehicle has high accuracy.Although the values of the chassis crossing ditches and obstacle-crossing heights obtained by different analysis methods are different,they all show similar variation laws.In clay road,the simulated longitudinal and transverse ultimate slip angle is close to the theoretical calculation value.