Wheel Corner Modules : Technology and Concept Analysis

Abstract: The wheel corner module represents a new technology for controlling the motion of avehicle. It is based on a modular design around the geometric boundaries of a conventionalwheel. The typical WCM consists of a wheel containing an electrical in-wheel propulsion motor, a friction brake, a steering system and a suspension system. Generally, the braking,steering and suspension systems are controlled by means of electrical actuators. The WCMis designed to easily, by means of bolted connections and a power connector, attach toa vehicle platform constructed for the specic purpose. All functions are controlled viaan electrical system, connecting the steering column to the module. A WCM vehicle cancontain two or four wheel corner modules.The purpose of this thesis is to serve as an introduction to wheel corner module technology.The technology itself, as well as advantages and disadvantages related to wheelcorner modules are discussed. An analysis of a variety of wheel corner module concepts iscarried out. In addition, simulations are conducted in order to estimate how an increasedunsprung mass aects the ride comfort and handling performance of a vehicle.Longitudinal translation over two types of road disturbance proles, a curb and a bump,is simulated. A quarter car model as well as a full car model is utilized. The obtainedresults indicate that handling performance is deteriorated in connection to an increase dunsprung mass. The RMS value of the tire force uctuation increases with up to 18%,when 20 kg is added to each of the rear wheels of the full car model. Ride comfort is deteriorated or enhanced in connection to an increased unsprung mass, depending on the disturbance frequency of the road. When subjected to a road disturbance frequency below the eigenfrequency of the unsprung mass, ride comfort deterioration is indicated. The RMS vertical acceleration of the sprung mass increases with up to 6%, in terms of the full car model. When subjected to a road disturbance frequency above the eigenfrequency ofthe unsprung mass, decreased RMS vertical acceleration of up to 25% is noted, indicatinga signicantly enhanced ride comfort. Implementation of wheel corner module technology enables improved handling performance,safety and ride comfort compared to conventional vehicle technology. Further development, e.g. in terms of in-wheel motors and alternative power sources, is however required. In addition, major investments related to manufacturing equipment andtechnology is regarded as a signicant obstacle in terms of serial production.