Gain Scheduling for Semiactive MR Dampers

Control of semiactive devices, such as magnetorheological fluid dampers for mitigating earthquake- and wind-induced motion of structures, is often accomplished using a clipped-optimal approach. This control strategy uses a primary optimal controller designed assuming the devices were active, linear and ideal, and a secondary bang-bang controller to make the semiactive device produce forces that mimic, as closely as possible, the desired active control. With multiple control devices, one or more may be inactive at any one time when the corresponding desired force is non-dissipative and cannot be exerted by a semiactive device. This approach effectively uses a gain scheduling type of approach, but it has not previously been studied in that context. This paper investigates a variety of schedule combinations of control gains to determine which approaches strongly affect the performance of the closed-loop response and find optimal gain schedule designs. The example demonstrates that improvements of at least 15%, relative to a standard clipped-optimal control, are achievable with a simple gain schedule design.