| The market prospects of Electric Power Steering system is very broad and how to develop the rapid development of electric power steering system to adapt to the market changes is the focus of the research of the automobile manufacturers. Electronic control steering hardware- in-loop test platform is an effective tool for the development of steering system, which greatly shorten the development cycle and reduce the development cost of the steering system. But the accuracy of the resistance simulation system severely limits the performance of Electronic control steering hardware-in-loop test bench. In this paper, control strategy combined with the force close loop control and the feed-forward compensation control is used to improve the accuracy of the loading system.This dissertation is supported by the National Natural Science Foundation named “Research on the control mechanism and evaluation method of new steer-by-wire system based on the characteristics of the drivers”(No. 51575223) and “Research on Reconfigurable Integrated Chassis Control Strategy for Four-Wheel Independently Actuated Electric Vehicle”(No. 51505178). Build the electronic control steering test bench based on the d SPACE real-time simulation platform, establish the simulation model and analysis the stability of the loading system. Using torque and current double closed-loop control strategy to increase the control system dynamic response quality, feed-forward compensation control strategy is used to suppress the system surplus force. Finally, the effectiveness of the control strategy is certified by simulation and experiment. The main research work is as follows:1) Studying and comparing the research status of Electric Steering Test Bench and Electric Resistance Simulation System’s control strategy, analyzing the advantages and disadvantages of various load control strategies. Then, the significance of proposed research project is proposed and the loading control strategy of the electronic control steering test bench is studied to improve the loading precision.2) Build the electronic control steering test bench based on the d SPACE real-time simulation platform and introduce the architecture, components and working principle of the electronic control steering hardware-in-loop test bench. The bench includes the hardware and control principle of steering system loading test bench, software and hardware system of the d SPACE real-time simulation system. Establish the loading system, tension-compression sensor and steering system model. Using the least square method to identify the electric parameters of the permanent magnet synchronous motor and the parameters of the mechanical system is identified by the acceleration and deceleration method. Then, the transfer function of the model is deduced.3) Analyzing stability of loading system. Using the root locus method to analysis the pole position of the loading system and Bode diagram is used to analysis the stability margin of the system. The influence of moment of inertia, damping coefficient and sensor stiffness on the stability of the system is analyzed. Correct control system by the way of zero-pole assignment to improve the stability of the system. Analysis the effects of the control parameters on the dynamic response of the system by simulation. At last, the system is simulated and tested. The results show that the system has good dynamic quality after the correction.4) Suppressing the surplus force of the loading system. Elaborate generation mechanism of surplus force and analysis the surplus force channel characteristics by frequency domain analysis method. The influence of moment of inertia, damping coefficient and sensor stiffness on the surplus force of the system is analyzed. Design the feed-forward controller based on structure invariance principle and speed feed-forward compensation. At last, the system is simulated and tested. The strategy proposed in this dissertation can suppress surplus force obviously and improve the accuracy of the loading system significantly. |
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