Optimum Design of a Tractor Steering Trapezoid Based on a Hybrid Genetic Algorithm

Tractor is the main tool of agricultural production and transportation, the performance of its various advantages and disadvantages directly affect the quality of agricultural operations. Agricultural wheeled tractor steering ladder mechanism, is the main component of the steering system. Steering trapezoidal mechanism design is good or bad, directly determines the performance of the tractor in the steering driving. To reduce tire wear during tractor steering, in this research, the steering ladder of a 75 HP tractor is optimized. The length and the initial bottom angle are determined through kinematic and geometric analysis of the steering trapezoid. The initial bottom angle is the design variable, with the actual variable angle and theoretical expectations. The relative error is the objective function. A mathematical model for the optimization design of the tractor steering trapezium is established, and a MATLAB program is developed using a hybrid genetic algorithm (HGA) to solve the problem. The results show that the steering arm length is 240 mm before optimization, the initial bottom angle is 64°, the steering arm length is 210 mm after optimization, the initial bottom angle is 61° and the objective function decreases from 19.5% to 17.8%. The verification test was carried out in the agricultural machinery test base of Anhui Agricultural University (China). The experimental results show that the RE between the measured average and the optimized the initial bottom angle is 1.49%, less than 5%. This shows that the results obtained by HGA optimization are feasible and provide a reference for improving the performance of tractor steering system.