The Effect of Time Delay of the Semi-Active Dampers on the Performance of On-Off Control Schemes

Abstract

With the new advancement in the vibration control strategies and controllable actuator manufacturing, the semi-active actuators (dampers) are finding their way as an essential part of vibration isolators, particularly in vehicle suspension systems. The currently available semi-active damper technologies can be divided into two main groups. The first uses controllable electromagnetic valves. The second uses magnetorheological (MR) fluid to control the damping characteristics of the system. Despite different semi-active control methods and the type of actuators used, one important practical aspect of all hydro-mechanical computer controlled systems is the time response (delay). The longest time response (delay) is usually introduced by the actuator (in this case, controllable actuator) in the system. This paper investigates the effect of time response in an on-off controlled suspension system using semi-active dampers. Numerical simulations and analytical techniques are deployed to address the issue. The performance of the system due to the time response is then analyzed and discussed. Specifically, the effect of the time response on the performance of a quarter car suspension system controlled by conventional on-off control strategies such as Skyhook and Rakheja-Sankar (R-S) is studied. Finally, the test results measuring time response in a newly developed semi-active actuator (namely, an external solenoid valve damper) is presented. Based on the real data and numerical simulations, the performance of a one degree of freedom quarter car system using this actuator is presented.

Structured magnetic circuit for magnetorheological damper made by selective laser melting technology

“…The use of current controller instead of the voltage controller can significantly reduce the overall response time [6]. Although many studies simulating suspension systems with MR dampers controlled by semi-active algorithms do not take into consideration the response time of MR dampers [7][8][9], papers [10][11][12] showed the considerable influence of the MR damper response time on suspension efficiency. The simulations and measurements showed that for a passenger car with a typical unsprung mass natural frequency of 18 Hz, the primary response time (0%-63%) must be much shorter than 8 ms.…”

Nonlinear analysis of switched semi-active controlled systems

“…While studying and performing numerical and experimental studies on the issue of response time of semi-active dampers [15], it was clear that if the response time of a semi-active damper increases, the added nonlinearity effect diminishes. This observation initiates the idea of this modified controller.…”

“…As depicted, the proposed system eliminates the added nonlinearities effectively. It is important to mention that this process will deteriorate the performance of the semi-active control systems [15] to some extent and, as a result, each case should be studied individually and the proper filtering parameter (a) determined. This process is also dependent on the response time of the actual semi-active actuator used in the system.…”

Semiactive Control of High‐Speed Railway Vehicle Suspension Systems with Magnetorheological Dampers

“…Huang et al thought that the integral time constant brings time delay into the semiactive control system, and the value is about 30 ms [25]. Eslaminasab and Golnaraghi measured that response time delay of the MR damper is about 10 ms, but response time delay of the solenoid-type damper is about in the range of 12.5∼16.5 ms [26,27]. Cha et al believed that a MR damper of 200 kN capacity needs 18 ms to reach the required control current and 550 ms to reach the required damping force [28].…”