MTS Acumen - Manual (Page 76)

Basic Closed-Loop Control in MTS Acumen Systems
1. When you enter an increase tension manual command through the MPX software, a command is sent
to the controller. This command instructs the digital controller to generate a signal that represents the
direction and amount of force the actuator needs to apply to the specimen to accommodate your
command.
2. The digital controller generates this command and sends it to the electrodynamic motor, which retracts
the actuator.
3. The actuator moves and imparts tension the specimen.
4. The force sensor (load cell) senses the amount of tension and sends this feedback to the digital controller,
where it is compared with your command.
The system automatically repeats Steps 2 through 4 until the desired command is achieved. The digital
controller continues to generate commands to the load frame to maintain the commanded force on the
specimen.
Understanding Control Modes
A control channel commands actuator movement by providing a drive signal to the electrodynamic motor.
The electrodynamic motor causes the actuator to move, which applies forces to the specimen. The selected
control mode determines how the commanded force is applied to the specimen. Only one control mode
can be active at a time per control channel.
Your system is equipped with force, displacement, and stable displacement control modes:
• Force control mode and displacement control mode are tuned on a per-specimen basis and may not
be stable if specimen characteristics change.
• The stable displacement mode is is tuned to optimize actuator control stability for all specimen types
to be used during set-up. As such, this is a low performance mode and is not intended for running tests.
76 | MTS Acumen ™
Key Concepts