Differential Control System for Rhombus-Chassis Electric Vehicles With Independent-Powered Wheels

Abstract

Light electric vehicles (LEV) have been developed for the interests of green, low pollution and low noise. The development of in-wheel motors improve electric vehicles’ power efficiency and simplify the transmission system design. However, to coordinate the wheel torques and their angular velocities becomes an issue, which affects the vehicle’s dynamics and handling stability. In this paper, an electric differential system (EDS) for a rhombus-chassis EV is focused on. The relation of driving wheels’ speeds was derived particularly for rhombus configuration, and it has been carried out on a control system. Compared to the conventional control strategy for three-wheeled vehicles, the proposed method could estimate a more accurate turning center with sensing the tail wheel’s rotating angle that is beneficial to smoothen vehicle’s cornering with a more adequate differential relation. Experiments were carried out with a real concept car “ITRI LEV 1,” and tests such as straight-line test, constant-radius test, and Slalom turn test were conducted. The results show the EDS could effectively improve vehicle’s maneuverability and stability. The required steering angle became larger and trending to under steering while enabling the proposed EDS system, and wheel skidding was also effectively prevented in both constant-radius and Slalom turn tests.