Research On Optimal Design Of Large Steering Angle Steering Mechanism Of Garden Tractor

With the development of modern agriculture,horticultural tractor as an indispensable power machine for agricultural production,often needs to work in the environment with steep slopes and many bends,such as orchards,tea groves and fields.However,the steering angle is small and the steering performance is poor because of the steering mechanism of the existing horticultural tractor,so it is unable to complete some turning operations on narrow terrain.Therefore,in order to increase the steering angle and improve the steering performance of horticultural tractor,a kind of detachable trapezoid steering mechanism with steering angle up to 57 ° is taken as the research object in this paper,and a two-population differential evolution algorithm based on firefly mutation mechanism is proposed to optimize the design of the steering mechanism with the minimum square error of the actual steering angle and the ideal steering angle as the optimization objective.Firstly,the steering principle of the steering mechanism of horticultural tractor is analyzed by means of analytic geometry,and the kinematic relationship between the steering angles of the inner and outer wheels in the steering process of the steering mechanism is studied,and the optimization objective function is established,which takes the rocker arm,steering rod,trapezoid bottom angle and hydraulic cylinder outer offset as the optimization parameters and takes the square minimum error of the actual and theoretical steering angle of the outer wheel as the optimization objective by using the kinematic relationship between the components.Secondly,a two-population differential evolution algorithm based on firefly mutation mechanism(IGDE)is proposed to optimize and analyze the objective function.The results were compared with four kinds of optimization methods: GA toolbox,basic differential evolution algorithm(DE/rand/1),variation factor randomized differential evolution algorithm(RMDE)and multi strategy adaptive differential evolution algorithm(ADEMP),the optimal objective function value was reduced by 41.6%,29.05%,17.34% and 15.19% respectively.It is concluded that the superiority of IGDE algorithm and the optimal design parameters of the broken trapezoid steering mechanism.Thirdly,the three-dimensional model of the front drive axle of the optimized steering mechanism is established,and the kinematics and dynamics simulation of the optimized steering mechanism are carried out.It is concluded that the simulation curves of the steering angle of the inner and outer wheels are the same as that of the steering curve drawn under Matlab,and the strength of the steering rod meets the design requirement as the transferor of the movement and force in the steering process.Finally,the steering angle of the optimized steering mechanism is measured by the test experiment of the front drive,and comparing with the simulation results of ADAMS and the calculation results of the proposed algorithm.The results show that the three relation curves of inner and outer wheel steering angles have the same trend and good coincidence,and it is verified that the proposed algorithm is correct and the steering mechanism design is reasonable.