Understanding Control Channels And Control Modes; Control Channel (For Example, Actuator); Control Modes (For Example, Force Or Displacement); Using Control Modes - MTS Systems Landmark 370 Series Operation

Key Concepts

Understanding Control Channels and Control Modes

Control Channel (For example, Actuator)

Control channels command actuator movement by providing a valve driver signal to the servovalve.
The servovalve causes the actuator to move, which applies forces to the specimen.

Control Modes (For example, Force or Displacement)

A control channel includes one or more control modes. Control modes determine how the commanded
force is applied to the specimen. Control modes typically include force and displacement. Only one
control mode can be active at a time per control channel.

Using Control Modes

When setting up your station for testing, you will select control modes at various times, such as;
When using the Manual Command panel to position the actuator to install and remove the
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specimen
When using the Station Setup window to optimize system response
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When you start a test, you lose the ability to select control modes manually. The controller
automatically switches to the control mode selections programmed into the test procedure.

Control Mode Example

Suppose you want to compress your specimen using the Manual Command panel.
If you choose force control, the test system will apply a compressive force to your specimen in
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terms of Newtons (or pounds) of force. If you enter a 1000 Newton command and the
specimen is relatively soft, the actuator will travel several millimeters (or inches) to achieve the
command. Likewise, If you apply the same command and the specimen is relatively hard, the
actuator will travel a fraction of that distance to apply the same force.
If you select displacement control, the test system will move the actuator in terms of
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millimeters (or inches) of displacement. If you apply a 10 millimeter command to a soft
specimen, the actuator may apply only a small force to the specimen to achieve the command.
If you apply the same command to a hard specimen, the actuator will apply a much greater
force to apply the same displacement.
Using Detectors and Actions to Protect Yourself and
Your Equipment
When set properly, MTS FlexTest detectors can minimize the risk of injury to yourself and damage to
the specimen. They can also inform you when something wrong or unexpected occurs, and let you
know when something you expect to occur, such as the specimen failing, actually occurs.
50 Landmark™ Test System Operation