# Soft Rehabilitation and Nursing-Care Robots: A Review and Future Outlook
## 2 Mechanical Design
### Soft Rehabilitation and Nursing-Care Robots Based on the Soft Intelligent Materials Actuation
#### 2.2.1 Pneumatic Fiber Braids and Elastomeric Polymers  
The application of pneumatic fiber braided fabrics and elastic polymers in the field of SRNCRs has been studied for many years. The most typical soft actuator is the pneumatic artificial muscles actuator [47]. The main body of the pneumatic muscles is usually a rubber tube covered with braided fabrics. One end is connected with proportional electromagnetic valves to regulate the internal air \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Robots** & **Aims** & **Assistance Capacity** \\ \hline Soft robotic exomusculture glove [19] & Providing help for the movement and coordination of gripping exercises & A maximum 15N grip assistive force in one DOF \\ \hline Tendon actuated soft robotic exoskeleton for hemiparep upper limb rehabilitation [20] & Providing assistance for patients in finger and elbow movements & \\ \hline Exo-glove [21] & Providing rehabilitate for patients who cannot open or close hands but can use other joints of the upper limb & 46\({}^{\circ}\)/48\({}^{\circ}\) for MCP/PIP ROM; 20N of pinch force; 76 mm diameter of maximum gripping object \\ \hline AirExGlove [27] & Suitable to provide rehabilitation to stroke patients affected scoring up to 3 in the MAS & Maximum diameter of graspable objects: 140 mm(100 Kpa), 190 mm (200 Kpa), 230 mm(200 Kpa) \\ \hline Soft robotic exo-sheath for hand rehabilitation [34] & Providing rehabilitation and activities of daily living assistance for stroke and spinal cord injury patients & 30.71\({}^{\circ}\)/ 75.64\({}^{\circ}\)/ 109.11\({}^{\circ}\) for MCP/ PIP/ DIP(palmar) \\ \hline Bio-inspired soft wearable robotic device for ankle–foot rehabilitation [35] & Designed for ankle–foot rehabilitation and sagittal ankle motions & A range of 27\({}^{\circ}\) for test subject’s ankle \\ \hline Soft wearable knee extensor [36] & Helping the physically weak people to walk & \\ \hline Soft wearable robotic ankle-foot orthosis [37] & Providing assistance for ankle-foot-rehabilitation & A 70N assistive force in the test \\ \hline Soft exosuit [40] & Providing unilateral assistance during walking and improving patients’ gait symmetry and paretic limb propulsion & A positive effect on temporal symmetry and paretic limb propulsion \\ \hline Hybrid rigid-soft hand exoskeleton [46] & Providing assistance and rehabilitation for patients with with neuromuscular impairment & 72\({}^{\circ}\)/66\({}^{\circ}\) for MCP/PIP ROM \\ \hline \hline DOF = degree of freedom, MCP = metacarpophalengeal, PIP = proximal interphalangeal, ROM = range of motion, DIP = distal interphalangeal. & \\ \hline \end{tabular}
\end{table} 
Table 1: Overview of soft rehabilitation and nursing-care robots based on tendon-driven actuation. pressure, and the other end is closed. Pneumatic muscles usually have much greater elasticity on one side than on the other to form a difference in axial contraction force and bend them. Pneumatic muscle can only be contracted by tension, which is a kind of unidirectional action element. In order to achieve complete rehabilitation exercise, pneumatic muscles are usually designed for configuration. McKibben muscle is a typical representative, which was invented by physician [PERSON] in the 1950s [48]. It is a bladder tube actuator packaged in a braided sleeve wrapped in a braided sheath. In 2013, [PERSON] et al. proposed a new silicon soft actuator and integrated it into a wearable rehabilitation glove (Figure 3a) [49]. The main material of the glove is an elastic fabric (neoprene) that fits the fingers to the maximum extent at all bending angles of the joint. Performance test results of actuators show that they can bend more than 320\({}^{\circ}\) and provide enough force to help patients to close fingers passively. Shortly afterwards, they also proposed multi-segment soft actuators [50; 51]. Based on this, an integrated hydraulically actuated soft rehabilitation glove was designed (Figure 3b) [52].