Design And Optimization Of Steering System Of Wheeled Transporter In Mountainous Orchard

As hilly mountain fruit industry has became a kind of typical hilly agriculture in China,and the mechanization of transport has became a core requirement in hilly mountain orchard operation.In order to improve the handling stability in transport operation,wheel conveyor of hilly orchard was analyzed in this paper to design steering system,which was relying on the public welfare industry(agriculture)research projects 'Development and Demonstration of Key Equipment in Field Mechanization'.First of all,according to the work requirements of conveyor of mountainous orchard,combined with the vehicle situation from the economic considerations to design mechanical steering system,which focused on the steering gear design of steering system.Then established Vehicle dynamics model through the simulation software CarSim,and validation test was conducted according to GB standard.Results showed that the response time of yaw rate(body-fixed)was too long for 0.88 s,so it was necessary to optimize the steering system.Therefore,the booster unit was added on mechanical steering system to shorten the response time of the yaw rate.In various forms of booster,Electric Powe r Steering System(EPS)is a new kind of intelligent Power Steering System.It has solved the long-standing conflict between steering portability and sensitiveness,which has enhanced the handling stability of vehicles in driving,especially in steering.The n,assist characteristics of EPS were studied based of the analysis of the structure of electric power steering system.According to semi-empirical formulas,the curve parameter of linear assist characteristics were determined and built up EPS control system mode by MATLAB,then united vehicle dynamics model and EPS control system mode.A joint simulation was presented by EPS model,constructed by MATLAB,and vehicle model,constructed by CarSim,and validation test was conducted according to GB standard.Results showed that the stable value of yaw rate(body-fixed)and lateral acceleration value of optimized vehicle in steering transient response(step input)test and steady static circular test had decreased obviously.So,compared with mechanical steering system,the design of the steering system and optimization scheme is reasonable and effective.In this paper,virtual prototype simulation experiment was adopted in the design and optimization of steering system,which shortened the design cycle and saved the design cost.It can provide reference for the design and optimization of other agricultural steering system to a certain extent.