| With the development of agricultural equipment to intelligent direction,its automatic driving technology has become a research hotspot.Drivability is usually determined by the walking mechanism,so it is necessary to study the motion characteristics of agricultural equipment for a class of walking mechanism to provide technical support for its automatic driving.Agricultural equipment complex ground condition,even if is the automated driving technology is relatively mature wheel machines,such as tractors,research methods and lay particular stress on machines and path tracking,deviation correction algorithm based on experience and so on,but not much research on the causes of deviation,lead to autopilot design method of versatility and adaptability is not strong,the field debugging workload big.Straight line driving performance is an important index to evaluate the level of agricultural equipment automatic driving technology,and the steering characteristics of different agricultural equipment and different working ground are the main factors affecting the straight line driving performance.In the design of automatic driving system,if the characteristic parameters can be predicted,it can improve the efficiency of development and debugging of the same kind of machine and enhance adaptability.Crawler wheel is a kind of typical walking mechanism in agricultural equipment.It not only has the characteristics of flexible steering of wheeled mechanism,but also has the advantages of small ground pressure and good passability,which can adapt to a wider operating environment.Based on the intelligent agricultural equipment group previously developed by jiangsu university a caterpillar wheeled mobile platform as the research object,the moving platform is in the nature of agricultural machine tools,functions similar to the tractor,can be articulated plough,fertilizer,pesticide and so on the many kinds of machines,its performance is theoretical analysis,simulation calculation and field test,specific work contents and results are as follows:(1)Refer to the literature to understand and summarize the development situation,steering kinematics and dynamics research status of all kinds of machinery and tools with crawler wheel structure at home and abroad.(2)The steering characteristics of tracked wheeled mobile platform are analyzed,and the calculation method of turning radius is deduced under ideal conditions and actual working conditions with the influence of slippage.The force of tracked wheeled mobile platform was simplified,the steering resistance was analyzed,the steering dynamics equation was established,and the theoretical steering radius was obtained..(3)A steering parameter measurement method based on machine vision is designed and verified by Beidou navigation satellite system.The results show that the error of machine vision measurement method is less than 10 cm,which can meet the requirements of field test and has good economy.At the same time,soil characteristic parameters and steering resistance were measured for the analysis of steering characteristics.(4)Using Recurdyn software,the virtual prototype and ground model of tracked wheeled mobile platform were created.The simulation results of steering radius and steering resistance were obtained under different speed and ground parameters.(5)Through the field steering test of tracked wheeled mobile platform,the simulation is verified and modified with the test results of steering resistance and steering radius.The influence of ground parameters and steering speed on steering resistance and steering radius was calculated and analyzed by using the modified simulation method.The formula of the relationship between ground parameters,steering speed and steering radius represented by soil moisture content was fitted.The maximum error was 5.43% of the test value. |
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