| Independent Modal space Control (IMSC) is a well established method in active control of vibration. In this method, the control law is developed exclusively in the modal space, allowing for independent design of modal control forces. These forces are then transformed to the physical space by modal transformation. The resulting controller is fixed-gain, with the active damping introduced to the system determined independently for each mode. This damping is directly proportional to the modal velocity in the under-damped case. In this research, we propose to use IMSC to articulate a new control architecture. The result is a new non-linear control law, embedding fuzzy reasoning that transforms the standard algorithm from a fixed-gain, to a variable-gain controller. This new algorithm uses information about the state profile (velocity or displacement) across the sensed locations to distribute the active damping rationally among the modal controllers. It complements the local view of the traditional algorithm in the modal space, with a global view of the velocities in the physical space. Three variants of the new control architecture are developed, discussed and studied in this research, and their performance compared with the standard method. A simulation model of a vibration control system is developed in LabVIEW development environment, where the performance of the fuzzy/IMSC method and its variants are simulated. Parametric studies are performed on the new architecture, where the effect of algorithm delay, and actuator omission are analyzed. The results show significant improvement in the settling time as the performance criterion, and the total amount of modal work done. |
