Model Based Study of Stability Limits for Three Wheeled Vehicles Using ADAMS/Car

Abstract

Three-wheeled motor vehicles have been around for close to a half a century now, but they have largely remained in the realm of recreational or concept vehicles. Due to increasing fuel prices and an emphasis on fuel efficient design, the automotive industry is exploring the three-wheeled option now more than ever as a mainstream daily-use vehicle. The trend is evident from the Automotive X-Prize which featured six teams with three-wheeled vehicle designs to meet the fuel efficiency target [1]. A three-wheeled vehicle design offers vast potential for improvement in overall fuel efficiency over their four wheeled counterparts, as it lends itself to a tear-drop shape which is highly aerodynamic and is also likely to be lighter and have lower rolling resistance. These factors have considerable impact on improving fuel efficiency, but such a design also presents challenges in terms of vehicle stability and can be susceptible to roll-over or spin out in certain scenarios. The primary factor that determines the stability of a three-wheeled vehicle is its center of gravity (CG). This paper uses a model-based approach to explore the CG position limits for stable operation of a front wheel drive three wheel vehicle and aims to give an empirical basis for deciding CG position limits for future three wheel vehicle design. ADAMS/Car is used to model the vehicle and the model is validated using test data from a commercially available three-wheeled vehicle. The performance of the model is then studied for various CG positions and the limits of safe operation are established for this particular model.