MTS Landmark System - Manual (Page 55)

needed unless a component in the load train changes dimensions substantially. On the load frame used
in the typical system in this manual, you use the hydraulic lift and lock controls on the load frame control
panel to position the crosshead.
Positioning the Actuator to Install the Specimen
You typically position the actuator every time you install a specimen. On the typical system used as an
example in this manual, you use the Manual Command panel in the Station Manager application to position
the actuator. If your system includes a Model 494.05 Handset, you can also position the actuator using
the handset.
Optimizing System Response Before Testing
Optimizing system response is referred to as tuning.
Why Tuning Is Beneficial
Tuning optimizes system response by adjusting the system so that its servoloop responds accurately to
its command signal. When you tune, you are setting the stability and optimizing the response of the
servocontrol loop. Proper tuning improves the performance of your MTS system in the same way that
performing a tune-up on an automobile improves its performance.
Loop Tuning for the Example Test
In the example test you adjust tuning at two points in the procedure:
Setting Initial Values to Ensure Stability
The first point is before you install the specimen or apply hydraulic pressure to the station. The purpose
is to ensure servoloop stability. In this case you simply set tuning controls to conservative values.
Adjusting Values to Optimize Performance
The second point is after you install the specimen, but before you run the test. The purpose is to optimize
system performance with the specimen in the loop. In this case you apply a cyclic waveform command
and adjust tuning parameters so that the feedback (system response) is as close to the system command
as possible. When this is achieved, the system response is optimized for that particular specimen. If you
want to test a different specimen that has different performance characteristics, you will have to adjust
tuning values for the new specimen.
Understanding and Resolving Error Conditions
Resolving error conditions is a normal part of operating an MTS Landmark System. You typically identify
and resolve several error conditions during setup and testing.
MTS Landmark Test System Operation | 55
Key Concepts