Multi-loop tests control two or more shakers on a single axis or multiple ones. Each output drives a separate shaker to more closely replicate the operational environment. Three-axis, four-post, and dual-shakers are examples of multi-shaker testing.
Download Demo All Software ModulesMulti-loop control refers to a vibration test setup with multiple shakers running on the same axis or different axes. There are many ways to configure a multi-shaker vibration test. The two key characteristics of a configuration are the number of shakers and the number of axes/degrees of freedom.
A multi-loop test requires a VR10500 enabled with multiple loops. The VR10500 supports 2 to 4 outputs. The primary VR10500 controller must drive all outputs, but the system can have stacked controllers for more than 16 inputs (up to 512).
The Sine, Random, Shock, and Field Data Replication (FDR) test modes can simultaneously run 2, 3, or 4 output drive loops.
To run a multi-loop test with a VR9500, the lab must have one VR9500 per control loop, each enabled with the necessary VibrationVIEW software.
In the automotive industry and other applications, engineers use multiple shakers for multi-axis vibration testing. Multi-shaker tests are time-efficient and reflect real-world applications. There are several multi-axis testing methods, each with benefits and considerations.
Multi-shaker Control VRU Course
Run a vibration test in the three linear directions simultaneously.
Three-axis testing performs vibration control on a triaxial shaker using identical or individualized test profiles. The VibrationVIEW software supports different profiles for random vibration tests, and the test systems are compatible with any electrodynamic or servo-hydraulic shaker.
3-axis Control
Synchronize two shakers with the same test profile.
Dual-loop with phase control synchronizes two shakers moving on the same axis while maintaining phase through level changes. It uses two outputs of a VR10500; the drive and COLA outputs from one controller drive multiple shakers with the same test profile. The result is a synchronized set of shakers, ideal for complete system testing of a larger device.
Alternatively, dual-loop can be run without phase control (offset) in Sine to replicate a setup in the end-use environment.
Dual Loop Phase Control
Control four shakers moving along the same axis.
A four-post test employs multi-loop control on four shakers moving along the same axis. Engineers often run these tests on complete vehicles. They place a shaker under each wheel and play back four field recordings from each wheel. Then, the recorded vibrations are played back simultaneously as if the vehicle was in motion.
Four-post Control
