| The Commercial vehicles have gradually become one of the main tools of road transportation in my country,but the accident rate of commercial vehicles is also increasing,which seriously endangers the life and property safety of drivers.Therefore,there is an urgent need to improve the driving stability of vehicles and reduce transportation risks.The steering system is the main mechanism that controls the direction of the vehicle,and it is also an important part of the intelligent driving technology of the car.Electro-hydraulic Coupling Steering System(EHCS)is widely used in commercial vehicles.On the basis of basic steering control,it integrates functions such as variable assist with speed,active correction,and corner servo mode to make the vehicle have good handling characteristics to ensure driving safety.At present,the core technology of EHCS is monopolized by foreign countries,and the domestic research and development of EHCS is not yet mature.In order to promote the localization of EHCS,this paper analyzes the system plan of EHCS in detail,studies the control strategy of the booster motor which plays a key role,and designs the core controller and software system of the system,and builds an EHCS hardware-in-the-loop test bed with simulation function.The design is analyzed and verified,and the control characteristics of the system are explored.The research work is as follows:Firstly,the EHCS scheme is analyzed,and the working principle and working characteristics of the electro-hydraulic coupling of the system are explored.Research on the operating mode of the steering assist motor in the system.Based on the structural analysis of the permanent magnet synchronous motor,mathematical modeling of the motor in different coordinate systems is carried out,and the three key parameters of current,speed and rotation angle are proposed.The corresponding control strategy.The application occasions of these control strategies were explored,and the experimental verification of different working conditions was carried out.Secondly,the design work of EHCS core controller and embedded software system was carried out.In terms of controller design,through the analysis of EHCS functional requirements,the design process of the controller is proposed based on the principles of signal integrity and power integrity,and the circuit design of each part is carried out with a modular concept to realize the functional application of the system.Through the circuit simulation results and the performance test results of the controller,the validity of the design is verified.In terms of software system design,the EHCS software system is divided into three parts: upper-level strategy,functional interface and bottom-level driver,and the software environment is configured to achieve efficient code conversion.In EHCS,the control strategy and controller of permanent magnet synchronous motor are combined for practical application,and safety protection functions such as fault diagnosis and program online update are developed on the basis of good steering control,which improves the reliability of the system.Finally,an EHCS hardware-in-the-loop test platform was built,and real-vehicle experiments were carried out to further verify and optimize the design of this article.According to the functional analysis of EHCS,the corresponding design plan is proposed,and finally a test platform that can meet a variety of experimental conditions is developed.The motor control experiment was carried out on the test platform to verify the stability of the coordinated operation of the control strategy,the controller and the software system,and conduct experiments with Lane Keeping Assist(LKA)function on commercial vehicles,which verified the rationality of the design in this paper.The experimental results show that the controller runs reliably,the software program conversion is efficient,and the motor works smoothly,which can provide key components and technical support for the localization of EHCS. |
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