Optimization of four-bar parameters steering linkage based on flat model

Abstract

Controllability of multi-axle vehicles depends significantly on the kinematics of steerable wheels, which is determined by the parameters of the steering system, one of which is the steering linkage. With such vehicles having more than one steering axle, the steering linkage parameters of each steering axle shall ensure that the steerable wheels are rotated to different angles. At suboptimal parameters of steering linkage and steering drive the vehicle controllability, stabilization of steerable wheels, tire durability decreases, fuel consumption increases.

The algorithm of calculating kinematic parameters of a four-link steering linkage based on a flat model is proposed. Microsoft Excel calculates theoretical and real steer angles, optimizes the basic coordinates of the steering arm. The difference between the theoretical and actual steer angles of the wheels of the first and second axles of the KrAZ-7634 HE obtained from the steer angle. The boundaries of the zone of optimal values of the coordinates of the base point are determined. It is established that for the first steerable axle the existing design of the steering linkage provides satisfactory steering kinematics. For a second steerable axle, it is advisable to change the location of the base point А₀ by moving it to the area of optimal coordinate values. This will reduce the difference between the theoretical and actual steer angles of the inner and outer steerable wheels and improve the kinematics of the rotation.

The proposed approach improves the accuracy and speed of calculations. The developed algorithm allows to analyze the influence of the design parameters of any wheeled vehicle on its steering kinematics and to optimize the design parameters. The application of the Solution Search module of the Microsoft Excel environment does not require sophisticated mathematical operations to optimize. The kinematics of a real spatial steering drive, on which the ratio between the steer angles of the wheels of the first and second steerable axles depends, as well as the question of the influence of the kingpin inclinations angles on the accuracy of the calculations, needs further research.