MIMO Shaker Systems
There are many different types of multiple shaker table arrangements based on MIMO testing applications.
Multi-Exciter Single-Axis (MESA), is an application in which multiple exciters provide dynamic input to a test item along a single axis. For cases in which the two exciters are driven to a common specification with respect to both phase and amplitude, the output may be described basically in one axis of excitation. For cases in which the two exciters are driven to independent magnitude and/or phase specifications, the output may need to be described in terms of a forward axis and aft axis, and perhaps, a rotational axis about the test item’s center-of-gravity (CG).
Note that the system would require appropriate bearing assemblies to allow a pure rotational MESA or combined linear and rotational motion. The following photo illustrates a dual shaker vertical push-push arrangement.
Three axis shaker tables are available for Multiple-Exciter Multiple-Axis (MEMA) test arrangements. Many testing applications require testing the DUT in simultaneously all three directions. With a three- axis shaker table system, the overall testing time is reduced by two-thirds over single-axis testing along each axis. More importantly, it identifies failures otherwise undetected with single-axis testing.
The automotive industry has been running tests on their vehicles for decades using four poster testing systems. Nowadays, with the availability of sophisticated MIMO control, testing with four posters is raised to another new level. The time waveform recorded from the testing tracks or real road conditions can be accurately reproduced inside the lab.
The vibration environment is incomplete without rotation. The MEMA Type 6 DOF Shaker Tables are available for these types of testing. The arrangement of shakers among all three axes allows the row, pitch, and yaw to be achieved along with the three-dimensional translation motions from the table.
The following six-DOF testing table consists of eight electro-dynamic shakers arranged along all three directions. Four shakers under the table will provide the excitation along the vertical axis translational motion together with the roll and pitch rotational motion. The four shakers, with two along each horizontal direction, will excite the table to generate transverse and longitudinal translational motion, as well as yaw rotational motion.