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In an automotive suspension, a shock absorber plays a significant role to enhance the vehicle performances, particularly ride comfort and road holding. Because of its important influences on the overall vehicle performances, the understanding of its physical characteristics is essential. Thus, this paper develops a mathematical model of twin-tube shock absorber that is widely used in modern production cars. The model is derived based on a rational polynomial formulation. This formulation generally represents the flow behaviors of fluid across a restriction. Further, simulation results are compared to those obtained from experiments to determine the model accuracy. The result comparison illustrates that the model is able to describe the behavior of shock absorber with slight discrepancies.

This paper presents the polytopic modeling method and state variable observer design approach for semi-active suspension with changeable damping and variant stiffness elements. And such semi-active suspension system is suitable to be modeled as a dynamic polytopic system where the extreme vertices of damping and stiffness values are taken as the convex vertices of polytope. Thus, a dynamic polytopic model is the convex synthesis with all the vertex system dynamics and linear system theory can be applied to the system at each vertex. Herein, the conventional Kalman filter theory is utilized to design the observer for each vertex system, then the polytopic observer is formulated by a convex synthesis. The proposed observer design approach is testified by numerical study and vehicle test.

As an important class of nonlinear system, polytopic bilinear system is investigated. Combined with the properties of convex polytope, the nonlinear control for polytopic bilinear system is formulated by synthesizing nonlinear H∞ controller which is designed for polytopic bilinear system at vertices. For a semi-active suspension system with controllable damping and variant stiffness elements, it is easily modeled as a polytopic bilinear system model. In this case, the desired nonlinear control properties are pursued in making effective use of the changeable damping property while the variant stiffness is taken as the affine parameter of polytopic model. Therefore, polytopic bilinear system model could be reduced to a feasible problem by polytopic convex decomposition. Then the control problem of bilinear system model is to find a solution of nonlinear H∞ control.

The objective of this study is to introduce and assess a computational tool designed to facilitate product development via sensory scores, which serve as a quantifiable representation of human sensory experiences. In the context of designing ride comfort performance, the specialized terminology—either technical or sensory—often served as a barrier to comprehension among the diverse set of specialists constituting the multidisciplinary team. In a previous study by the authors introduced a tool that incorporated a model of sensory performance, utilizing sensory scores as universally comprehensible metrics. However, the tool had yet to be appraised by a genuine cross-functional team. In this study, the tool underwent evaluation through a user-testing process involving twenty-five cross-functional team members engaged in the conceptual design phase at an automotive manufacturing company.