Design Of Driving Robot For Electric Vehicle Driving Range Test

With the rapid development of electric vehicles and the increasingly strict test standards for electric vehicles in various countries,it is quite necessary to realize a driving robot while the traditional manual test methods can not meet the high requirements of electric vehicle testing due to some disadvantages of low repeatability,poor driving accuracy and easily getting fatigue when driving.In this thesis,an electric vehicle driving robot based on the continuous mileage test is designed,and the NEDC national standard working condition test is carried out on the indoor rotary hub.The purpose of this topic is to achieve an error-free,low-error elite driving result and to achieve a smooth pedal opening control according to the operation logic of human driving.Finally,the driving mileage results will obtain a higher accuracy and reliability.The main work of the thesis is as follows:1.The advantages and disadvantages of the design and control method of traditional driving robots are analyzed,and the hardware structure of the system is designed.After analyzing the characteristics of accelerating pedal,gear grip,brake and cruise components of the car,this thesis designs an electrical interface to simulate them and to replace the mechanical structure,and finally to realize the general control of the vehicle.The rotary hub states and AK instruction set are tested to analyze the response speed of mode switching and the control effect of constant speed or constant force instructions.Finally,it turns out that the auxiliary braking of rotary hub is feasible and reasonable.2.The software program of the system is designed and implemented,which mainly includes the lower computer control program and a user interface.The software of the lower computer is designed by modularization and hierarchy,which realizes the functions of vehicle learning,manual/automatic driving,data analysis and so on.In order to control the vehicle speed,this thesis divides the working conditions into 4 kinds of speed segment types,designs different control strategies for each speed segment,realizes the closed-loop control by measuring the actual speed as feedback by the external measurement of the hub,and tracks the speed by means of PID,preview,resolution control,setting control band and auxiliary braking using rotary hub.The user interface of the host computer is implemented,which includes the functions of vehicle parameter configuration,interaction with the lower computer,data processing and security monitoring.Finally,the security design of the system is carried out to ensure the security of communication and operation.3.The speed tracking controller is studied and realized,which is mainly divided into two parts,such as establishing models and tuning PID parameters.Firstly,according to the step response of the electric vehicle accelerator pedal,a set of the simple first-order models of theelectric vehicle are established at multiple opening points.Secondly,the control advantages of internal model structure are analyzed,and the tuning method of PID parameters is studied.Finally,IMC-PID is realized based on stability margina.Through comparative experiments,it is verified that the PID parameters determined by the stability margin have better dynamic characteristics than the conventional approximation method and it can also meet the tracking requirements of the driving range test in this thesis.4.At the end of the article,a real vehicle test is carried out.Through tracking accuracy,pedal stability,pedal repeatability and other indicators,the effects of manual driving and robot driving are compared,and the effectiveness of this scheme is verified.Finally,a safety test is carried out to verify the completeness and reliability of the system,which is also a qualified engineering scheme.