Proc. SPIE. 7288, Active and Passive Smart Structures and Integrated Systems 2009
KEYWORDS: Mathematical modeling, Data modeling, Amplifiers, Control systems, Algorithm development, Control systems design, Performance modeling, Systems modeling, Device simulation, Instrument modeling
The increased prevalence of semi-active control systems is largely due to the emergence of cost effective commercially
available controllable damper technology such as Magneto-Rheological (MR) devices. Unfortunately, MR dampers are
highly nonlinear, which presents an often over-looked complexity to the control system designer. The well-known
Skyhook Damping control algorithm has enjoyed great success for both fully active and semi-active control problems.
The Skyhook design strategy is to create a control force that emulates what a passive linear damper would create when
connected to an inertial reference frame. Skyhook control is device independent since it generates a desired control
force command output that must be produced by the control system. For simplicity, MR dampers are often assumed to
have a linear relationship between the current input and the force output at a given relative velocity. Often this
assumption is made implicitly and without knowledge of the underlying nonlinearity. In this paper, we show that the
overall performance of a semi-active Skyhook control system can be improved by explicitly inverting the nonlinear
relationship between input current and output force. The proposed modification will work with any semi-active control
algorithm, such as Skyhook, to insure that the controller performance is at least as good as the performance without the
proposed modification. This technique is demonstrated through simulation on a quarter-vehicle system.