Self-propelled aerial work platform which is called Self-AWP is a special vehicle,intended to move persons to working positions by extending structure. The fastest speed of the Self-AWP is 6.8km/h which is very slow. When the working place is farther, it takes much time to drive the Self-AWP to the destination, and it is banned to drive on the road. So the truck or trailer is need, but the width of the truck or trailer is limited. In order to transport the Self-AWP expediently, the width of the Self-AWP should be as short as possible. So the wheel expansion technology or extendable axle technique which is able to change the width is used in the Runshare chassis. There are two states of the tread. One is a narrow width when the Self-AWP is in transportation condition. The other is a wider width when the Self-AWP is in working condition. As there are two states of the tread, there are two steering mechanisms and steering errors. And how to reduce the two steering errors at the same time?
Firstly, the use of the steering mechanism with extendable axle in Self-AWP is described.Then the model of the steering error of the steering mechanism with extendable axle is established. And the concept of double-error is established at the same time.
Secondly, according to the double-error of steering mechanism, the model of the double-error is established as a multi-objective problem. In order to eliminate the sideslip of the tire, the mean relative error square is consider as the objective function, and the base angle and the waist length are consider as the design variables. Then the boundary constraint condition and the performance constraint condition are established. With the MATLAB genetic algorithm toolbox, the multi-objective problem is solved using multi-objective genetic algorithm. The result of the multi-objective optimize problem is a set of Pareto. Based on pseudo-weighted vector method, the interested set is selected form the set of Pareto. And with a certain type of self-propelled aerial work platform as an example, it is improved by the multi-objective optimize technology and proves the feasibility and rationality of the optimization method.
Last, using the solution after the optimization evaluation, the optimal layout rules of steering mechanism with extendable axle are explored. And the base angle and the waist length are the most important two parameters for steering mechanism. The least square method is used for data processing technology, dealing with the optimization data after evaluation.
