Research On Coordination Control Of DDAS And ESC Systems For Electric Vehicle Driven By Four In-Wheel Motors

Scarcity of fuel has brought in great concerns to human today. Gasoline, which has been the major power source of classical vehicles for decades, got its price soaring up year by year. This phenomenon results in an unstoppable trend of conventional vehicles replaced by new energy vehicles, motorized wheels vehicles is considered to be the universal driving platform of vehicles including EV, HEV, and FCEV owing to its simple structure and high efficiency in energy recovery[39]. Control strategies can be very easy in this platform since the electronics today is very mature, and now motorized electric vehicles(MEV) have been mass produced by many famous manufactures including Ford motor and Peugeot Citroen. MEV hold more DOF than conventional ones since the differentials have been canceled, because of which the novel driving form can have the properties of generating yaw moment without braking. The moment can become the control force both in DDAS and ESC systems and the stability of the vehicle can be interfered, so it is necessary to find a way to make a compromise of the two properties.In this paper, a coordination control method based on slide mode controller and fuzzy logic will be provided to make MEV more stable and more lighter when cornering. The coordination control strategy will be researched by theoretical analysis,simulation as well as real vehicle test for validation,which can be described as follows:First and foremost, ideal mathematics model has been built which including 7 DOF model for the whole vehicle dynamics, steering model, tire model and motor model.etc. The reason of the interfere between DDAS and ESC has also been presented based on different working conditions. Still, calculation method of ideal variables were also been provided. An adaptive slid mode control strategy was also provided to maintain vehicle stability, before which ideas for necessary variables estimation and a logic of when sideslip angle can join the control were also described.Finally, a correct factor ki for the steering assist factor is given to lead the coordination control, after which the flow chart of the control theory was also listed.Secondly, simulation models had also been built by Carsim/Simulink to verify the performance of the coordination theory. Some simulation tests including double lane change test, single lane change test,sine wave change test and angle step test were also by implemented both in high speed and low speed. It is definitely that the coordination control method are not only more stable than the uncontrolled one, but also lower down the hand wheel torque of the driver sharply.At last, a real MEV had also been built for validate the practice value the coordination control method. The sensors and controller as well as design of electronic systems were also explained. In the test, Simulink/Stateflow and Dspace-microautobox were mostly used, communication between VCU and MCU is through can protocol. Double lane change and "J" test had been carried out for validation, it is obviously the coordination control strategy perform well through the comparison among the test curves,which demonstrate that the idea provided in the paper holds practical values.