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Optimum Response of a Nonlinear Passive Vehicle Suspension System under Random Road Excitations
Abstract:
The objective of the present article is to design a nonlinear passive suspension
system for an automobile subjected to random road excitation which generates a
performance as close to a fully active suspension system as possible. Linear
Quadratic Regulator (LQR) control is used to synthesize an active suspension
system. The control forces corresponding to the nonlinear passive suspension and
the active suspension are equated, and the parameters are optimized as the
performance error between the two systems is reduced. The nonlinear equations of
motion are reduced to equivalent linear equations, where the system states are a
function of the vehicle response statistics, by using the equivalent
linearization method. The performance of the optimized nonlinear model and the
linear model are compared with the performance of the LQR control active
suspension system. The nonlinear model performs better than the linear system
with chosen parameters. The optimized system achieves almost an equal response
to the active suspension system for ride comfort and road holding over the
specified velocity range. The optimum response of a passive suspension system
with nonlinear suspension elements is achieved using a novel optimization
method. This method provides design flexibility, and it has great engineering
importance for application in the design of various vibration control
devices.