Abstract
Research and/or Engineering Questions/Objective
In consideration of robustness, perturbations of vehicle’s parameters should be taken into account in the controller design of active suspension. As a result of structure non-linearity, suspension stiffness varies in different relative position between the sprung and unsprung mass, which would result in conservative control strategy. The objective of this study was to realize ideal stiffness characteristics of an electromagnetic actuated active suspension (EAAS) with cam mechanism and thus to reduce conservatism in the controller design.
Methodology
An analysis of the stiffness characteristics of the traditional active suspension has been carried out in order to figure out the mechanism of production of the stiffness’s non-linearity based on the complex vector method. On the basis of an EAAS, a novel cam mechanism design is used to eliminate the nonlinearity of the suspension stiffness and relative structure of the spring assembly has been introduced. Relative demonstration to realize ideal stiffness characteristics as well as the design procedure of the cam mechanism has been introduced. Computer simulation of the EAAS with the cam mechanism is used to support the analysis.
Results
In the paper the design procedure of the novel cam mechanism will be presented. Results show that this novel cam mechanism can realize ideal stiffness characteristics and the pressure angle of the cam mechanism is within 4 degree, which is acceptable in the structure design. A robust H∞ controller based on the EAAS with ideal stiffness has been designed. The controller is then applied on this EAAS as well as a traditional active suspension by using co-simulation of ADAMS and MATLAB/simulink. Results show that the novel cam mechanism design can give less conservative control strategy in the controller design of EAAS. Limitations of this study The friction of the cam mechanism hasn’t been taken into account in the design procedure, which may cause additional damping and slightly influence the accuracy of the cam design. Therefore, further study on the influence of the friction can be carried on.
What does the paper offer that is new in the field including in comparison to other work by the authors?
It’s a novel idea to realize ideal stiffness characteristics of EAAS by utilizing cam mechanism. The corresponding design procedure is provided in detail. Furthermore, the design of proposed cam mechanism provides potential to reduce conservatism of the EAAS controller.
Conclusions
A novel cam mechanism is designed to realize ideal stiffness characteristics of the EAAS and its effectiveness is verified via simulation. The design of EAAS controller would benefit less conservative results and the quality of active control is expected to be improved.
Key Words : Cam mechanism; Ideal stiffness characteristics; Electromagnetic actuated active suspension; Controller design