Translated Abstract
The power steering system is an important part of the heavy vehicle. The current steering wheel and the tire part are connected by mechanical connection, which has the disadvantages of complex design, high energy consumption and difficulty in modification. In recent years, with the rapid development of electronic technology, steering-by-way developed from aircraft transmission control has attracted people＇s attention, using steering-by-way, reducing the complexity of the system, realizing the distributed and intelligent steering system. At the same time, for heavy vehicles, because of its larger steering resistance than cars, it generally uses hydraulic power steering. And analysis of the existing hydraulic steering scheme, the steering system mostly use valve control system, and valve control system has high energy consumption, system complex and other shortcomings, and the opposite of the pump control system because of reducing the use of hydraulic valves, improve the system energy utilization, reduce the complexity of the system. This paper combines the steering-by-way with the pump control hydraulic system to build the hardware of the hydraulic power steering of the heavy vehicle in the ring test platform, and studies the control strategy of the hydraulic steering of the heavy vehicle. The main contents of this paper are as follows:
On the basis of the domestic and foreign research status and related literature of the hydraulic power of heavy vehicle line control, the shortcomings of the valve control system using proportional valve or servo valve and the pump control system using two-way pump are summarized, and a kind of linear hydraulic power steering with the combination of the reversing valve and the unidirectional pump is put forward to realize the hydraulic steering-by-way of the two-way pump. On the basis of this, the software and hardware of the system are designed. After the design is completed, the hydraulic power steering system of this paper is modeled. The feasibility of the proposed scheme and the rationality of the parameter design are verified by the simulation. Based on the design of online hydraulic power steering system, a hardware in loop test rig for heavy duty vehicle hydraulic steering is built.
For the hydraulic steering-by-way system with the pump control system, the time-varying nonlinearity of the system, and the slower response of the pump control system compared to the valve control system, these problems lead to the higher requirements for the control algorithm of the steering system. The controller needs to realize the steering test of the heavy vehicle line control set up in this lesson. The rapid and stable steering of the test platform. After consulting relevant literature, we choose fuzzy PID as the control strategy of this subject, and design the fuzzy PID controller by piecewise multiple acquisition. In the actual operation, the signal has interference due to the influence of some factors such as electromagnetic interference, system disturbance and so on. Based on the analysis of the signal category, the filter is designed to eliminate the interference.
On the loop test platform, the hardware of the heavy vehicle hydraulic steering-by-way is built on the test platform, and the fuzzy PID algorithm designed is used to test the controller under the condition of unload and variable load, and compare with the traditional PID. The experimental results show the feasibility of a new type of linear hydraulic power steering system with a two-way pump using the commutation valve and the one-way pump, and the average amplitude frequency characteristic of the fuzzy controller is greater than 0.95, the average phase frequency characteristic is more than -0.35rad, and the dynamic performance of the system is compared with the PID controller. And the steady state performance all have better control effect.
Translated Keyword
[Fuzzy Control, Power-assisted steering, Pump control, Steering-by-wire]
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