# Design Approaches of an Exoskeleton for Human Neuromotor Rehabilitation
## 3 Exoskeleton Functional Principle
Component **13** has a dumping system for shock-absorbing during walking motion when the patient body will modify the mass center in a vertical direction due to the foot and ground contact. In the case of exoskeleton right lower limb, the following revolute joints can be seen in Figure 7: **O**--right hip revolute joint; **E**--right knee revolute joint; **M**--right ankle and foot revolute joint. The right link equivalent to femur was labeled with **6** and for the right tibia can be found the link labeled with **5**. For the right foot equivalent link, this can be found  
Figure 7: Exoskeleton structural scheme. labeled with **11**. Thus, these links are actuated through two planar-parallel mechanisms, namely one for the right knee joint **E** and the other for the right ankle joint and foot **M**. Right hip joint is actuated directly through a chain transmission, respectively **TLSD**, by the **ASD** servomotor unit. Regarding the right knee joint actuation, this can be done by **AGD** servomotor unit through a second chain transmission labeled with **TLGD**, towards planar-parallel drive link mechanism situated at the femur level **6**. Thus, the motion from the drive chain wheel connected with the drive link **1** is transmitted through a revolute joint **A** to connecting rod **2**. This connecting rod **2** is articulated through the **B** revolute joint and will transmit motion to the support plate **3**. The support plate **3** is articulated onto the right femur equivalent segment by revolute joint **C**. Practically support plate **3** will perform an oscillating motion imposed to the connection link **4**, which is articulated through revolute joints **D** and **F**. This connection link **4** will actuate the right tibia equivalent segment **5** for a proper flexion motion. The second right planar-parallel mechanism is situated at the right tibia segment **5** and it will actuate the right ankle joint **M**. This mechanism will receive motion from the **APD** servomotor unit through a third chain transmission **TLPD** straight to drive link **7** situated at the right knee joint level. This drive link **7** motion will be imposed to another support plate **9** through connecting rod **8** articulated with revolute joints **G** and **J**. The support plate **9** will perform an oscillating motion towards the right tibia equivalent segment through revolute joint **K**. This motion is transmitted through connection link **10** to the right ankle and foot segment **11**, for performing the dorsal/plantar flexion during walking activity recovery. The connection link **10** is articulated by the whole planar-parallel mechanism through revolute joints **L** and **N**. In this mode the exoskeleton right lower limb will be actuated and the in case of the left limb, the motions are the same, only the difference is the exoskeleton architecture, where left lower limb is mirrored by a vertical plane from the right one. For this reason, the exoskeleton left lower limb functionality is similar to the right one, except for some small peculiarities, namely: **O'**--left hip revolute joint; **E'**--left knee revolute joint; **M'**--left ankle and foot revolute joint. The left link is equivalent to the femur was labeled with **6'** and for the left tibia can be found the link labeled with **5'**. For the left foot equivalent link, this can be found labeled with **11'**. These links are actuated by another pair of planar-parallel mechanisms, one for the left knee joint **E'** and the other for the left ankle joint **M'**. The left hip joint is actuated directly through a chain transmission, **TLSS**, by the **ASS** servomotor unit. Regarding the left knee joint actuation, this can be done by **AGS** servomotor unit through a second chain transmission labeled with **TLGS**, towards the planar-parallel drive link mechanism situated at the femur level **6'**. Thus, the motion from the drive chain wheel connected with the drive link **1'** is transmitted through a revolute joint **A'** to connecting rod **2'**.