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Objective

Validate the operation of the Festo 8540 dynamometer.

Description

In this section, the user is presented with a SIMULINK-based model to perform basic control over Festo 8540 dynamometer through the serial interface.

In this demo, the dynamometer will be operated in torque mode with the speed limit.
This means that the dynamometer will follow the torque reference if the speed limit is not surpassed. If the speed limit is reached, the torque reference will be automatically limited, so the speed limit is respected.
Worth noting that while operating the dynamometer in torque mode, the speed needs to be limited to avoid the risk of over-speed (which would be the case if the torque developed by the dynamometer surpasses that from friction and the load at its shaft).

Model Overview

The RT-LAB model depicted in Figure 1 consists of two subsystems. The “SM_OP5707” subsystem includes the model that runs on the real-time simulator; the “SC_Offline_User_Interface” subsystem presents the user interface that runs on the host PC.

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Figure 1: RT-LAB model overview

The “SC_Offline_User_Interface” subsystem consists of three areas, as shown in figure 2.

• The green area (dynamometer Control) send the reference to the dynamometer.

• The yellow area (Signal Monitoring) is used for receiving and monitoring data from the OPAL-RT simulator.

• The orange area (Instruction) provides important information about the model and its test procedure.

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Figure 2: Contents inside the SC_Offline_User_Interface subsystem

The SM_OP8660 subsystem has two main blocks, including the “Control Signal Receiver,” which receives the desired reference of the torque from the console.
The “Serial Communication” is also used to communicate with the dynamometer through RS232 protocol.

Connections

• The connection of the OP5707 simulator to the dynamometer is demonstrated below. Connect the connection signals as shown in figure 4.

Test Procedure

• Launch RT-LAB.

• Import project zip file (see below) in RT-LAB.

• Build, load, and execute the model.

• Turn on the 8540 dynamometer and, through its touch panel, enable its “Computer-Based Control,” as depicted in figure 5 below.
  In this operating mode, the user can monitor the state of the dynamometer: torque, speed (frequency), current, and voltage.

• Set a speed limit for the dynamometer. The allowed speed range for this demo is 0-1800 rpm.
  A recommended value is 1000 rpm.

• Set a torque limit for the dynamometer. The allowed range for this demo is 0-5 N*m.
  A recommended value is 0.7 N·m.
  Try different torque values close to 0.7 N·m and see the effect on the dynamometer’s speed.

• Enable the dynamometer by using the toggle switch.

• By setting a torque reference to 0.5 and speed to 1000 rpm. The following start-up results are expected on the 8540 touch bar.

• To stop the model:

  • Set the Torque reference to ’0′.

  • Set the dynamometer speed limit to ’0′.

  • Disable the dynamometer, by using the toggle switch from ’1′ to ’0′.

  • Turn off the dynamometer.

  • Reset the model in RT-LAB.

Conclusion

Based on the preceding tests, the hardware and software included in Festo’s models are declared fully functional and compliant with OPAL-RT specifications.

Model (Zip File)