Abstract
In this paper, a controlled system for an active-cab-suspension constructed with hydropneumatic actuators is considered, which is intended to improve ride comfort of a truck.
At first, a controller is designed using YJB parametrization of all stabilizing compensators and experiments is carried out to verify its feasibility. The parameter is determined by graphical technique in frequency domain so that the controlled system has sufficient ride comfort. Experimental results show that the considered active-cab-suspension can greatly improve ride comfort. But they also show the necessity of consideration for other factors of the controlled system such as transfer functions from measurement noises to the stroke length and to the control input.
Then practical design of the controller is proposed. This is based on H∞ control theory, that can achieve systematic loop shaping of multi-input/multi-output systems. The controlled system is augmented with frequency weightings to state its design as standard output feedback H∞ control problem. Relations between these weightings and some significant transfer functions of the system are mentioned. Decision of weightings is proceeded so that they shapes these transfer functions desirably. Simulations and experiments using measured actual vehicle acceleration data confirm that the resulting system has remarkable improvement of ride comfort with the limited stroke length, and high robustness against measurement noises. This shows validity of application of H∞ control theory to designing a controller of the active-cab-suspension.
