Study Of Power Steering By Driving Force For Electric Vehicle With In-Wheel-Motorized-Drive

In1886, Carl Benz made the first car. In1903, the Ford motor companyintroduces the T-model, and this is a bear for the public car and started massproduction. Nowadays，confronting with the stresses of the environmental pollutionand the energy consumption, vehicles propelled by the green energy are in urgentneed. Because the traditional vehicles with internal combustion engine could notcover the problems concerned above, it is the absolute trend of vehicle industry todevelop and apply electric vehicles for the society’s sustainable development. Themotorized-wheels-driving system is an excellent driving platform which could bringwith many predominant advancements for Evs(Electric Vehicles) and realize lots ofperformances that would not be completed on the traditional vehicles. By now,motorized-wheels-driving system has already become one of the hottest researchingfocus for vehicle manufactures in domestic and abroad, at the same time, under theimpelling of market need, serious environmental pollution and the enormous energyconsumption, many companies have promote their electric motorized products whichperform well in every aspects. The dissertation makes an in-depth research on thesteering department of motorized-wheels-driving platform. Power steering systemplays a vital role in the driving system, which could not only reduce the steeringtorque on steering wheel, as a result, prevent the driver from unnecessary fatigue, butalso provide enough road information for drivers at proper time. Through the modeland simulation results, this paper is to make a further analysis on driving forcepower steering and validate the feasibility of the technology.First and foremost, the dissertation introduces the background of EV, and gives abrief statement about the researching and applying situation of in-wheel motor and motorized-wheels-driving system. Accordingly, puts forward the conception ofpowering steering by driving force and represent the theory and advancementcompared with the EPS(Electrical Power Steering System). In this Abstractive oncaption, independent powering steering motor and its relative power steering moduleson electric motorized vehicles are replaced by the in-wheel motors which give boththe driving torque and the power steering torque. This view is put forward for the firsttime in the world. After conducting the dynamic analysis, with the knowledge of Mathand Physics, dynamics model and computer-simulation model are made up using theAMESim and MATLAB/Simulink software.After analyzing the theory of driving force power steering and verifying thefeasibility of the technology from the dynamics perspective, the writer establishes a15DOF model with AMESim and Simulink. The model of Magic Formula is used toconstruct the dynamic model system. This dissertation simplifies the complicatedsteering system into two parts of physical modules, including rotating subassembly ofsteering wheel and shifting subassembly of pinion. The dissertation analyzes theresistance and makes up the math model of resistance torque in pivot steering. Thisjoint simulation platform has more freedom, and is very close to the actual vehiclestructure. Besides, its signal is easy to collected.According to the characteristics of driving force power steering technology, thispaper formulated the direct torque control strategy, and set up the reference steeringwheel hand power curve. This curve, according to the parameter of the futureexperimental vehicle, after checking many relative literatures, is established based onenormous experiments and the evaluations from many experienced drivers.Additionally, PID controlling arithmetic is chosen for the fundamental calculatingarithmetic of the controller for its simplicity, reliability and stability. It is proper forearlier researches when establishing controller. Finally, takes the torque difference ofIn-Wheel Motor as the controlling parameter of the power steering controller. Thisdifference is easy to obtain and has a direct effect on the drivers’ steering torque.Based on the vehicle dynamic model established through AMESim software and MATLAB/Simulink we make a large number of simulation tests and analyse results.By combining the simulation model of steering system with vehicle simulationplatform, Computer simulation is conducted to testify the authenticity of steer modeland the validity of control strategy. From the simulation result, we could see that thesteer model constructed in this dissertation could reflect the movement and stressingof every part in steering system. Moreover, PID control arithmetic fundamentallysatisfies the demand of power assistant controller and could truly perform an efficientpower assistant in both steady state and transient state during steering process, as aresult, reduce the drivers’ steering torque and achieve the desired purpose of the study.It can be seen from these results, the driving force power steering system has thefunction of assisting steering.