MTS Series 793 Application - Manual (Page 186)

MTS MultiPurpose TestWare®
Cyclic Command Process
Command Processes 186
Cyclic Command Process
About the Cyclic Command Process
The Cyclic Command process defines a cyclic command by assembling two
single segments and repeating them continuously for a specified number of
cycles.
When a cyclic command starts, it always moves first to End Level 1, and then to
End Level 2.
Sine, ramp, and square
start levels
Sine, ramp, and square commands use the first segment of the cyclic command to
bridge any difference between the current level and the cyclic command End
Level 1 that you specify. This transition segment is counted as the first segment
A high-speed transition segment can result in an unwanted spike (or bump)
in your command signal.
Unwanted command-signal spikes can damage the physical test specimen.
To avoid spikes in the command signal, use a segment command process to
bridge processes where end levels and start levels differ greatly. If a process end
level is not near the start level of your cyclic command process, the process uses
the first segment to move all the way from the current level to the start level at the
transition speed that you specify.
True sine start levels True sine commands start at the mean level, which is the midpoint between the
End Level 1 and End Level 2 you specify. The system begins a true sine cyclic
process by stepping from the current level to the mean level. (This step does not
count as a segment.)
Once at the mean, the command travels through End Level 1 at the specified
rate. When using a true sine command, you should design your procedure so that
the system is at or very near its mean level before the true sine process begins.
You can include a segment command process that ramps from the current level to
the mean level. If you do not, your system may experience a step (or jolt)
between processes. The more difference there is between the current level and
the true sine command’s mean level, the greater the step.
CAUTION