A quarter-car experimental analysis of alternative semiactive control methods

The performance of three semiactive control policies, including the well-kn own 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, an d a magnetorheological damper that is built and tuned for the purpose of th is study. Upon describing the mathematics of the three semiactive control p olicies and the construction of the quarter-car rig, the results of a serie s of experiments with each control policy are presented. The transmissibili ty plots of the test results confirm the features of each control policy, a s discussed in the past analytical studies. The results indicate that skyho ok control can significantly reduce the transmissibility of the sprung mass , as compared with passive dampers. Similarly, groundhook control substanti ally reduces the unsprung mass transmissibility. For vehicle applications, reducing the sprung mass transmissibility often results in improving the ri de comfort, and reducing the unsprung mass transmissibility provides less w heel hop, therefore resulting in better road holding ability and improved v ehicle stability. The test results for hybrid control, which is intended to provide a combined effect of skyhook and groundhook, indicate that it hold s the promise of achieving a semiactive control policy that can be slowly a dapted to the driving condition and vehicle dynamics for better vehicle sta bility and ride comfort.