| With the progress of society,the development of automobile technology and the improvement of road traffic,people have a better requirement on the stability,comfort and safety of automobile operation.Vehicle steering performance is one of the most important performance in the process of driving,and the electric power steering system is a new type of power steering system,compared with the traditional power steering system,has the advantages of simple structure,small size,active safety,energy saving and environmental protection,installation and maintenance convenience.EPS system adopts motor to provide steering directly,and then through the electronic control unit analysis,calculation and control,real time according to the car’s speed,road conditions and other information to provide the appropriate steering,has turned to light when the car in low speed,high speed when the performance of the steering stability,the EPS system has become a hot power steering technology research.Firstly,this paper discusses the background,development status,research status and working principle of electric power steering system at home and abroad.At the same time,the part of power motor is analyzed.Secondly,STM32F103ZET6 single-chip microcomputer was used to drive the power motor,and BTS7960 chip was used to improve the driving ability of the single-chip microcomputer.Programs were written to collect the corner signals.On the basis of MCU driving motor and improving driving ability,it can provide power according to the state of the car in real time.The power characteristic curve of EPS was designed,and the fuzzy control rules were established by using fuzzy control strategy.Combined with the differential equation of the steering system,the EPS system model was established in MATLAB/Simulink,and the relationship curves of steering wheel Angle,steering torque and lateral acceleration were simulated and analyzed under different conditions.According to the relationship curves,it can be seen that the operating stability of the EPS system was improved.Through the analysis of the relationship between the power torque,it is shown that the power characteristic curve and the control system determined in this paper have a good power effect,which can meet the requirements of low speed steering plate light,high speed and stable operation.The nonlinear dynamic model of seven degrees of freedom is established,and the nonlinear tire model of Dugoff is adopted to know the feasibility of the magic formula.In seven degrees of freedom nonlinear dynamic model at the same time the original steering system on the basis of improvement,add model controller and other control parameters,to map the steering wheel Angle,control torque,the curve of the lateral acceleration,the effectiveness of the proposed controller is verified by contrast,can solve the problem of EPS system original steering heavy,and the problem of torque ripple.Finally,the hardware of EPS system was built on the ring platform with the help of PXI of NI company,and the joint simulation test was conducted with CarSim and LabVIEW RT.The experiment of the hardware in the loop platform shows that it has certain path tracking ability,and also verifies the effectiveness of the control strategy.The stability of the steering system in the laboratory environment is demonstrated by the vehicle test.Figure [86] table [5] reference [54]... |
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