# Enhancing Robotic-Assisted Lower Limb Rehabilitation Using Augmented Reality and Serious Gaming
## 5 Evaluation of System Effectiveness and Usability Assessment  
In order to validate the rehabilitation system, a series of in-lab tests using healthy subjects were performed. During the test, the serious gaming app was used and the subjects were asked to play the game using three scenarios: for the first run, the subjects were asked to try to maintain as good as possible the motion trajectory with respect to the game-defined trajectory (target trajectory--blue color in Figure 15); this first scenario is represented with the green dotted line in Figure 15. The second scenario implied the same target trajectory, but this time, the subjects were asked to create some variation of the game in terms of trying to deviate from the trajectory in order to imitate the patient's inability to maintain the trajectory; during this run, the system did not interfere with the rehabilitation process, resulting in the poor following scenario without correction represented with the red color in Figure 15. The third scenario implied the same target trajectory, and again, the subjects were asked to try to derive from the target trajectory, but this time, the system was set to record the deviation and intervene with path correction trajectories in order to get as close as possible to the target trajectory. This run is represented as poor following with correction with the black dotted line in Figure 15.  
In order to observe any differences between the three scenarios, a standard deviation analysis was performed. The results are graphically represented in Figure 16. For the first scenario where the subjects were trying to maintain the target trajectory, a standard deviation of 0.44\({}^{\circ}\) was obtained for hip adduction/abduction motion, 0.48\({}^{\circ}\) was obtained for hip flexion/extension motion, 0.49\({}^{\circ}\) was obtained for knee flexion/extension, 0.50\({}^{\circ}\) was obtained for ankle flexion/dorsiflexion, and 0.50\({}^{\circ}\) was obtained for ankle inversion/eversion. For the second scenario where the subjects received no correction from the system and deviated from the target trajectory, a standard deviation of 2.89\({}^{\circ}\) was obtained for hip adduction/abduction motion, 3.12\({}^{\circ}\) was obtained for hip flexion/extension motion, 2.73\({}^{\circ}\)  
Figure 15: Path representation during the functional validation tests: blue color—target trajectory; green color—scenario 1 trajectory (good target path following); red color—scenario 2 trajectory (poor target following with no system correction); black color—scenario 3 trajectory (poor target following with system correction). was obtained for knee flexion/extension, 2.71\({}^{\circ}\) was obtained for ankle flexion/dorsiflexion, and 2.92\({}^{\circ}\) was obtained for ankle/inversion version. For the third scenario with system correction, a standard deviation of 1.65\({}^{\circ}\) was obtained for hip adduction/abduction motion, 1.81\({}^{\circ}\) was obtained for hip flexion/extension motion, 1.84\({}^{\circ}\) as obtained for knee flexion/extension, 1.50\({}^{\circ}\) was obtained for ankle flexion/dorsiflexion, and 1.78\({}^{\circ}\) was obtained for ankle/inversion version. As can be observed, the standard deviation was considerably reduced with the path correction algorithm, with 57% for hip adduction abduction motion, 58% for the hip flexion/extension motion, 67% for the knee flexion/extension motion, 55% for the ankle inversion/everson motion, and 60% for the ankle inversion/everson motion. To analyze the user experience with the system, a User Experience Questionnaire (UEQ) [39] was completed by the 12 participants (the questionnaire is attached to Appendix A, of whom only two had prior experience with the HoloLens device (Figure 17). The results of the analysis are presented in Figure 18. The Attractiveness of the application received a high mean score of 1.59, placing it in the \"Good\" to \"Excellent\" range. This suggests that users find the system visually appealing and engaging.