A demonstration system for dynamically substructured systems and their control

Abstract

Most engineering systems are required to be tested dynamically. However, conventional tests can encounter difficulties such as size constraints, unavailability of system components at the design stage, nonlinearities and cost. One way to overcome such problems is the dynamic substructuring technique, the main advantage of which is that it can allow the full-scale testing of critical, possibly nonlinear, components within a laboratory environment. Thus, the dynamically substructured systems (DSS) methodology enables critical components of a complete (or emulated) system to be physically tested in real-time, while the rest of the system is modelled numerically. An ideal DSS therefore results in perfect synchronization of displacements or forces at the interfaces between the physical and numerical substructures. To achieve this ideal, high-quality control must be utilised to compensate for nonlinearities, time-varying/uncertain parameters and the presence of additional actuator dynamics within the physical substructure. This paper addresses a generalized DSS framework and associated controller design strategies. It also includes implementation tests on a visually appealing demonstration rig (a train DSS). Furthermore, the effectiveness of the DSS testing technique is verified by comparing its responses with those of a physically emulated and a numerically emulated system. These tests reveal that the DSS most closely represents the behaviour of the emulated systems when state-space synthesis techniques are adopted and an adaptive element is included, in the control strategy.