Development of a systematic and practical methodology for the design of vehicles semi-active suspension control system

Abstract

In this paper, a novel systematic and practical methodology is presented for design of vehicle semi-active suspension systems. Typically, the semi-active control strategies developed to improve vehicle ride comfort and stability have a switching nature. This makes the design of the controlled suspension systems difficult and highly dependent on an extensive trial-and-error process. The proposed methodology maps the discontinuous control system model to a continuous linear region, where all the time and frequency design techniques, established in the conventional control system theory, can be applied. If the semi-active control system is designed to satisfy some ride and stability requirements, an inverse mapping offers the ultimate control law. At the end, the entire design procedure is summarised in six steps. The effectiveness of the proposed methodology in the design of a semi-active suspension system for a Cadillac SRX 2005 is demonstrated with road tests results. Real-time experiments confirm that the use of the newly developed systematic design method reduces the required time and effort in real industrial problems.

Keywords:

• semi-active suspension systems
• Fuzzy systems
• nonlinear separation theorem
• Skyhook control policy
• systematic approach
• sub-optimal Skyhook strategy
• road test verification

Acknowledgements

The authors would like to thank the Phoenix research team at the University of Waterloo and Simon Fraser University. Also, the financial support, provided by Mechworks Systems Inc. and Ontario Centres of Excellence, is greatly appreciated.