# Design Approaches of an Exoskeleton for Human Neuromotor Rehabilitation
## 6 Exoskeleton Experimental Tests  
The performed experimental tests were done in laboratory conditions, using a similar protocol to the one presented at the human experimental analysis for creating the desired database. Thus, the time interval for performing a complete gait cycle was considered as equal with 1.45 s. This time interval is the same as the one for mathematical models processing and virtual simulations environment. Also this interval was setup in a closed-loop for achieving four complete steps in a total time of 5.8 s.  
For the experimental evaluations, motion video analysis equipment called CONTEM-PLAS was used, which is similar to VICON Equipment, except for the fact that it uses only two cameras and has the advantages of being mobile equipment. Thus, by having a similar working principle, a total of 10 reflexive markers were attached to the exoskeleton prototype limbs, respectively in the main joint centers of the desired characteristic points (hip, knee, and ankle joints for each lower limb), as can be seen in Figure 23.  
Thus, several snapshots during these tests were presented in Figures 24-26. Informed consent was obtained from all subjects involved in the study. Figure 23: Markers’ positions for the exoskeleton prototype experimental tests: (**a**)—right lower limb; (**b**)—left lower limb. Figure 24: Snapshots during exoskeleton left ankle joints without foot and ground contact. Figure 25: Snapshots during exoskeleton left knee joint without foot and ground contact. These tests were performed without foot and ground contact to observe the exoskeleton behavior during walking exercises. This experimental evaluation process was not used by any human volunteers to test this and other experimental tests will be presented in future research. After processing the video sequences, the desired results were obtained for both exoskeleton lower limbs. These are shown in Figures 27-29. Analyzing the presented diagrams in Figures 27-29, it can be seen that the obtained angular variations have similar trajectories with the ones obtained in the case of mathematical models' processing and virtual simulations, but also in the case of the experimental analysis of a healthy human subject. Thus, in the case of the hip joints, values between \(-26.785\) and \(16.238\) degrees were recorded, and the angular amplitude in the case of the analyzed exoskeleton's hips was \(44.023\) degrees. By having insight into the previous experimental database and also the existent specialty literature data [23; 27], this angular amplitude is correct from a numerical viewpoint and it corresponds to a normal gait in the case of a healthy subject. On the other hand, the introduced data inside of the robotic system's command and control program contained data acquired in the previous experimental analysis of a healthy human subject case study. Regarding the exoskeleton knee joints, it can be observed in Figure 28 that an angular amplitude of \(47.753\) degrees was recorded, which is higher than a normal angular amplitude obtained in the case of a healthy subject. This high value was obtained due to the high inertia momentums of the exoskeleton segments corroborated with high angular speeds. In future experimental test protocols, this will not affect the patient recovery behaviour  
Figure 28: Exoskeleton knee joints angular variation for a complete gait without foot and ground contact. Figure 29: Exoskeleton ankle joints angular variation for a complete gait without foot and ground contact. due to fact that these high values were recorded in knee flexion moments during the swing phase of a complete gait. It is possible that the use of a patient together with the designed robotic system prototype will increase the stiffness and this angular amplitude will record lower values.