| Steering gear as an implementation structural of the aircraft, its performance has a decisive influence to the precision-guided aircraft. Because the guided vehicle steering gear need to adapt to the special environment, the Servo system must has some characteristics, for example, the high output torque, fast response, small volume, and high reliability. Ordinary steering gear is difficult to meet the requirements. In the field of aeronautics and astronautics,electric steering gear is the research focus. It is small in size, light weight, and easy to maintain. which can meet the special requirements of modern guided vehicle. The purpose of this paper is to design and development a set of electric steering gear prototype which make high performance of digital processor DSP to be the control core of the system and use modern intelligent control technology to realize fully digital and intelligent of steering gear, to improve the performance of electric steering gear.Firstly,this article introduces the overall structure of the steering gear system, and describe each part of electric steering gear briefly, analyzes working principle and mathematical model of brushless dc motor in detail. According to the various parts of the electric steering gear structure and mathematical model, combined with the actual form all parts of electric steering gear form, the electric servo system of the whole simulation model is set up in simulink.According to the characteristics of electric steering gear, Servo system adopts three closed loop control strategy. The inner current loop and speed loop use PI control, position loop, as the controller of the outer ring, has a decisive influence on the performance of the steering gear. Therefore, the position loop is designed with the PID control and fuzzy PID control and fuzzy PID control and variable region of three different control algorithms in this paper. Compared with the three control algorithms in the simulation experiment, the results prove that the experiment used fuzzy PID control and variable region of three different control get a best control effect, the next one is simulation used fuzzy PID control, simulation used PID control algorithm get the worst result.Secondly, according to the overall structure of the electric steering gear, the steering gear system software and hardware is designed. The TMS320F28335 type DSP is selected as the core of the Electric steering gear hardware system. According to the requirement of system and the DSP processor peripherals, the DSP minimum system circuit, SCI serial communication, motor driver module and all parts of the signal conditioning circuit is designed. The software system is designed with DSP main program, interrupt service program and control algorithm program included. The control algorithm is the core of the system program, refer to the simulation results,PI control algorithm is used in servo system of current loop and speed loop, the DSP PID algorithm and fuzzy PID control arithmetic is used in position loop.At last, the software and hardware debugging of the system is completed. In this experiment, different control algorithms used in the control system is compared in the actual system. The experimental results and simulation results are identical with each other, the fuzzy PID control is better. The experimental results also prove that, the design of electric steering gear system scheme is feasible, its performance achieves the expected goal. |
