# A Parallel Robot with Torque Monitoring for Brachial Monoparesis Rehabilitation Tasks
## 2 Materials and Methods
### Experimental Setup and Torque Control Validation  
After the development of the torque-monitoring system, a series of in-lab tests were performed to validate the improved control system after receiving ethical approval to carry out the experiments. Ten healthy subjects were selected for the experiments from the research center staff and the experimental setup was defined. Figure 12 presents the ASPIRE robot placed in CESTER research center within Technical University of Cluj-Napoca for performing experimental tests. The robotic structure is physically attached to the control unit and because the participants in the experiment were healthy subjects and the main objective of the experiment was to validate the torque-monitoring system, a regular chair was used (during the previous tests performed in the hospital the patients were carried to the rehabilitation system using a wheelchair). Figure 11: Homing process flowchart. Besides the robotic system, a sensor system was used (Biometrics [44]). The sensor system uses a series of goniometers to simultaneously measure the angles in up to two planes of movement. During the experimental tests two goniometers were used. One was placed under the armpit of the subject to measure angles in two directions (flexion/extensions and adduction/abduction of the shoulder) and the other one was placed on the forearm of the subject to measure the rotation of the wrist with respect to the forearm (pronation/supination of the forearm). The decision to place the goniometers in this position came after a series of tests that revealed the optimal position to obtain most accurate reading during the rehabilitation motion. An image regarding this aspect of the experimental test is shown in Figure 13 along with a figure of the subject performing shoulder rehabilitation using the ASPIRE system. The amplitudes recorded by the biomedical sensors were not passed to the control system of the robot; the sensor system uses a separate graphical interface to calibrate each goniometer, and, after the calibration, the time-based variation of the amplitudes is graphically represented. The calibration of each goniometer is performed before placing the sensors on the patient by placing both ends of the goniometers on the same plane surface at the same time and pressing the interface \"Calibrate\" button. The entire calibration procedure for each goniometer takes up to 15 s. Each goniometer can read values between \(\pm\)180 degrees with an accuracy of \(\pm\)2 degrees measured over a range of 90 degrees and a repeatability of \(\pm\)1 degree measured over a range of 90 degrees. The advantage of the system is given by the 12 h lasting battery and the wireless range up to 30 m. An example of the output of the sensor system for the pronation/supination motion is presented in Figure 14. The graph shows the rotation amplitudes recorded during a 20-repetitions session using a 50 degrees amplitude for pronation and 50 degrees amplitude for supination. Figure 12: ASPIRE experimental model. Classical rehabilitation protocol, previously used for the tests performed in the hospital, was also used for performing the in-lab experimental test. The subject was sitting on the rehabilitation chair with the shoulder resting in the shoulder plate. The forearm was attached to the forearm anchor device, and his palm was supported by the palm support. Using the GUI of the robotic system, motion amplitudes were introduced for each rehabilitation motion. While the robotic system was performing the motion, a background thread was used to monitor the torque. During this stage of the experimental test, the goniometers were used only for validating the motion amplitudes given within the user interface. Each of 10 healthy subjects received the same treatment, meaning the same motion amplitudes (maximum amplitudes), the same velocity during the rehabilitation, and the same number of repetitions.