A Brief History of Modern Digital Shaker Controllers
James Zhuge, Mark H. Richardson · Sound&Vibration · 2010
This article discusses four generations of digital vibration exciter control systems developed by U.S. companies over a period of 40 years. The controllers are categorized as standalone, PC-based, PC-tethered, and fully networked. The age of modern vibration controllers dawned in the mid 1970s with the maturity of the minicomputer and adoption of the fast-Fourier transform and related signal processing mathematics for practical vibration testing. Technical advancements borrowed from other fields gave rapid rise to a new class of digital closed-loop controllers. While commercial vibration test controllers existed previously, none of them was capable of running multiple types of tests such as sine, random and shock. The minicomputer and the personal computer which soon eclipsed it, provided a new level of flexibility in a tightly integrated testing system. This new architecture also provided superior control and a host of other benefits leading to better presentation, retention and communication of test results. The past 30-35 years clearly mark the golden era of rapid development in this field. We restrict our attention here to the most significant vibration control products of the years 1970 to 2010. This in no way suggests disrespect for some of the unique dedicated instruments that came before. Prior to this period, landmark work in swept-sine control was performed at Spectral Dynamics, Bruel & Kjaer and Solartron, with each company creating its own sophisticated commercial instrument solutions. In addition, MB Electronics is credited with developing the earliest random vibration controllers using analog filter banks. Much of the theory underlying today’s random control system designs can be traced back to the early work of Theron Usher at Yale University and at MB.