A hardware-in-the-loop approach to independent wheel control development using a physical scale model as a low cost prototyping tool : executive summary
Environmental legislation is driving research into new technologies for future automotive products. Electric vehicle technologies have the potential to meet these legislative requirements, but are currently restricted by cost implications. This work focuses on the potential for offsetting this cost against potential benefits of the technology. In particular, the application of a motor at each wheel, facilitating Independent Wheel Control (IWC). A scale model vehicle is incorporated into a Hardware-in-the-Loop (HIL) simulation for the application of developing IWC strategies. The model uses four motors, each driving a single wheel in order to effect this control. Control strategies are 'rapid prototyped' in MathWorks Simulink™ using an industrial standard tool, dSPACE™, to operate the strategies in real-time HIL simulation. The application of a control strategy, representative of a conventional 4x4 behaviour, incorporating a lockable centre differential is applied. Shaft compliance is modelled in order to provide a test of the system operation with a transient dynamic response. Stability issues raised through this application are related to signal processing. An estimator is devised in software to overcome these issues, producing a stable system response. The work concludes that the use of a physical scale model for the development of IWC strategies is inappropriate in the context of supporting the development of a full-scale vehicle due to the complexity of reproducing a scaled tyre. However, in a broader sense, the approach of utilising a physical model has demonstrated significant benefits in promoting the concept of lWC within an industrial organisation, and in assisting product development.