Design and evaluation on electric differentials for overactuated electric ground vehicles with four independent in-wheel motors

This paper discusses the design and evaluation of electric differentials (ED) for overactuated electric ground vehicles (EGVs) with four independent in-wheel motors. Three patterns of ED, namely, 1) front ED, 2) rear ED, and 3) all-wheel ED, are designed and discussed based on vehicle performances during normal cornering and circling maneuvers. Through both simulation and experimental results, the three different ED can achieve almost the same vehicle performances in terms of the EGV sideslip angle, yaw rate, and trajectory. Moreover, when an ED is applied to only one pair of wheels, i.e., either the front or rear pair, the other pair of wheels can be utilized to estimate (the passive tires are adopted as sensors under normal driving conditions) the EGV longitudinal speed and yaw rate and consequently generate the reference wheel speeds for the ED wheels. Thus, sensors for measuring the vehicle speed and yaw rate to generate the reference wheel speeds in the design of ED, such as the all-wheel ED design for the EGV, may become unnecessary. Both simulation and experimental results validate the designs of the three ED.