Crystal Instruments MIMO Shaker Systems

Multiple shaker tables are arranged in many ways depending on the MIMO test application. Multi-Exciter Single-Axis (MESA) drives a test item along one axis with several exciters; when two exciters are driven to a common specification in both phase and amplitude the output can be described as a single axis of excitation, but when they are driven to independent magnitude and/or phase the output must be described in terms of a forward and aft axis, and possibly a rotational axis about the test item's center of gravity. Such systems need appropriate bearing assemblies to allow pure rotational or combined linear and rotational motion, as in the dual-shaker vertical push-push arrangement.

For Multiple-Exciter Multiple-Axis (MEMA) arrangements, three-axis shaker tables are available. Many applications require testing the device under test in all three directions simultaneously; a three-axis table cuts overall test time by two-thirds over single-axis testing along each axis and, more importantly, identifies failures otherwise undetected with single-axis testing. The automotive industry has run four-poster vehicle tests for decades, and with sophisticated MIMO control the time waveforms recorded from test tracks or real road conditions can now be reproduced accurately in the lab.

The vibration environment is incomplete without rotation, which the MEMA Type 6 DOF shaker tables address. In one example, a six-DOF table uses eight electro-dynamic shakers arranged along all three directions: four shakers under the table provide vertical translation together with roll and pitch, while four more, two along each horizontal direction, excite transverse and longitudinal translation plus yaw.

During testing, all measurement input and drive signals can be recorded continuously to a Spider-NAS or the internal storage of each front-end and viewed with the Crystal Instruments Post Analyzer, with a variable sampling rate available to capture slow-change signals alongside high-speed vibration data. Every test supports status checks through EDM Cloud, where live data or run logs of completed tests are stored securely in the user's account and can be viewed from anywhere by authorized personnel.