A quarter-car experimental analysis of alternative semiactive control methods

The performance of three semiactive control policies, including the well-known skyhook control and two others that are referred to as groundhook and hybrid control, are studied experimentally. The experiments use a single suspension apparatus that is commonly referred to as quarter-car rig, and a magnetorheological damper that is built and tuned for the purpose of this study. Upon describing the mathematics of the three semiactive control policies and the construction of the quarter-car rig, the results of a series of experiments with each control policy are presented. The transmissibility plots of the test results confirm the features of each control policy, as discussed in the past analytical studies. The results indicate that skyhook control can significantly reduce the transmissibility of the sprung mass, as compared with passive dampers. Similarly, groundhook control substantially reduces the unsprung mass transmissibility. For vehicle applications, reducing the sprung mass transmissibility often results in improving the ride comfort, and reducing the unsprung mass transmissibility provides less wheel hop, therefore resulting in better road holding ability and improved vehicle stability. The test results for hybrid control, which is intended to provide a combined effect of skyhook and groundhook, indicate that it holds the promise of achieving a semiactive control policy that can be slowly adapted to the driving condition and vehicle dynamics for better vehicle stability and ride comfort.