Design Of Semi-active Suspension System Research Articles

Constrained optimal control: an application to semiactive suspension systems

This article applies three different control techniques to the design of a quarter-car semiactive suspension system. The three techniques, originally developed to solve a constrained optimal control problem, are optimal gain switching, discontinuous variable structure control and explicit model predictive control. All of them divide the state space into convex regions and assign a linear or affine state feedback controller to each region. The partition of the state space is computed off-line. During the on-line phase, the controller switches between the subcontrollers according to the current state. All the above techniques gave satisfactory results when applied to the design of semiactive suspension systems. A detailed comparison in terms of computational complexity, performance and simplicity of the design is proposed in the article.

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

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.

Integrated design of a quarter-car semi-active suspension system using a convex integrated design method

In this paper, a new integrated design method – the convex integrated design (CID) method – is introduced and applied to the design of a semi-active suspension system. The closed-loop system is required to simultaneously satisfy four closed-loop performance specifications: car body acceleration, suspension deflection, tyre dynamic load and control effort. With a simple two-stage algorithm, the mechanical structure design parameter, as the stiffness of the suspension spring in the semi-active suspension system, and the closed-loop controller are determined with the CID method. This leads to a closed-loop suspension system which in simulation, is shown to satisfy all four closed-loop performance specifications. Then the suspension system is redesigned with two closed-loop performance specifications, car body acceleration and energy of control effort, and through experimentation, the closed-loop performance is verified on suspension test bed. Both simulation and experimental results verify the effectiveness of the CID method, with two closed-loop performance specifications.

Modelling of continuously variable damper for design of semi-active suspension systems

The continuously variable damper is widely used in the semi-active suspension system since it can yield various damping forces at a given damper velocity. By applying an appropriate control scheme to the damper, satisfaction of both ride comfort and driving safety can be realized. For successful development of the semi-active suspension system, a model that accurately describes the complex and nonlinear behaviour of the continuously variable damper is crucial. In this research, a modelling technique for the continuously variable damper has been studied. Various damper components have been analysed and their effects upon damper characteristics have been closely investigated. The effects of the damper characteristics change upon ride comfort and driving safety have also been investigated via simulations.