Adaptive control strategy for dynamic substructuring tests

Real-time dynamic substructuring, or hybrid testing, is a technique that enables experimental testing of critical elements of a complete structure. The structure in question is decomposed into at least two parts: the critical element, which is physically tested, and the remainder of the structure, which is modeled numerically. For accurate replication of the system to be emulated, the two parts must interact, via a controller to compensate for the actuator dynamics, in real-time, and with minimal errors at their interfaces. During development, the adaptive minimal controller synthesis (MCS) algorithm controller has previously been implemented for substructuring of a one-degree-of-freedom mass-spring-damper system. The potential advantage that MCS has over a traditional linear controller is its lack of reliance on detailed knowledge of the experimental specimen dynamics. This paper presents the MCSmd control strategy, an improved MCS-based strategy for substructure testing, using a modified demand (md) signal. Experimental and simulation studies of the MCSmd controller applied to a two-degree-of-freedom mass spring damper system are presented along with an analysis of the transient gain behavior.