A Random Vibration Control System for Testing a Single Test Item with Multiple Inputs

Random Vibration – History and Overview

“…This is important, for example, in the laboratory-experimental generation of coherent, stationary random signals for multi-axis testing. (See Smallwood, 1982a, and1982b. )…”

Modeling and identification of a triaxial shaker control system

“…If a control system is designed based on a model of the system characteristics, fidelity of that model can be crucial [2], especially if the test bandwidth includes system natural frequencies [3]. Alternatively, an adaptive control technique can be used; such techniques for controlling shaker systems have been developed [4] [5] [6]. Even if this type of technique is used, however, it is usually important to evaluate the algorithm's performance against a computerbased model, where the robustness of the algorithm can be quickly assessed for a range of model parameters.…”

The rules for the exchange and analysis of dynamic information in structural vibration

“…This results in the so called cross coupling effect among excitation sources that is due to exciter armature inertia [39,40].…”

“…This leads into an inverse problem [2] which is addressed in the following chapters for deterministic and random forces. This represents a real challenge in the vibration testing context since not only the ex citers must be able to generate and control a given frequency spectrum, but also cross Inlerfan Fonts Inltrfict Motion Figure 3.5 Laboratory test scenario where the test item inputs are defined from interface forces {Fc} or external forces {Fe} or interface motions {Xc} correlation between excitation sources must be maintained [39,40].…”

“…Small wood [39,40] outlines a procedure to test a single test item with multiple random inputs where it is shown that cross coupling effects between excita tion channels must be accounted for in the control process. No practical results of this procedure have been reported since its publication.…”