Best Vibrations paper at ASME DSCC 2016 for Irfan Ullah Khan
Irfan Ullah Khan, a PhD student at the University of Sheffield associated with (but not directly funded by) the EPSRC-sponsored Engineering Nonlinearity Programme grant, presented his research at the ASME Dynamic Systems and Control Conference in Minneapolis from 12-14 October 2016, where he picked up the award for best vibrations paper.
Irfan started an EPSRC-funded PhD in November 2013, working on structural vibration suppression using hybrid active plus semi-active control. His paper presented a new hybrid active and semi-active control method for vibration suppression in flexible structures. The method uses a combination of a semi-active device and an active control actuator situated elsewhere in the structure to suppress vibrations.
The key novelty is to use the hybrid controller to enable the semi-active device to achieve a performance as close to a fully active device as possible. This is accomplished by ensuring that the active actuator can assist the semi-active in the regions where energy is required. Also, the hybrid active and semi-active controller is designed to minimise the switching of the semi-active controller. The control framework used is the immersion and invariance control technique in combination with a sliding mode control. A two degree-of-freedom system with lightly damped resonances is used as an example system. Both numerical and experimental results are generated for this system and then compared as part of a validation study. The experimental system uses hardware-in-the-loop to simulate the effect of both the degrees-of-freedom.
The results show that the concept is viable both numerically and experimentally, and improved vibration suppression results can be obtained for the semi-active device that approaches the performance of an active device.