# A Review on Upper Limb Rehabilitation Robots
## 4 Examples of Rehabilitation Robots  
Designing a rehabilitation robot faces a few challenges that have to be considered first [33]. Electromechanical implementation is one of these challenges, which refers to that the robot has to be light, durable, flexible and have the mechanism to perform a normal muscle motion [20]. The interpretation of user intent is another challenge, where the human-robot interaction plays an important role in the rehabilitation process [33]. A neural muscle signal is one of the tools that is used to extract the user's intent [3]. In addition, a robot's degrees of freedom (DOF) and the safety precautions should be taken into account in designing the rehabilitation robot; otherwise, the safety and the efficiency of the robot will be compromised [3,34]. The following are some examples of well-known rehabilitation robots [35]. Table 3 summarizes the characteristics of the rehabilitation robots.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Type of Robot**Characteristics** & **Targeted Impaired Functions** & \begin{tabular}{c} **Number of DOF** \\ **Provided** \\ \end{tabular} & \begin{tabular}{c} **T therapy** \\ **Classification** \\ \end{tabular} & **Security Precautions** \\ \hline MIT-MANUS & Upper limb rehabilitation & Five DOF & Passive & \begin{tabular}{c} **Therapy** \\ **Classification** \\ \end{tabular} & **Security Precautions** \\ \hline MIT-MANUS & Upper limb rehabilitation & Six DOF & Passive & \begin{tabular}{c} **The** **a** \\ **Magnetic safety lock is** \\ \end{tabular} \\ \hline ARM Guide & Upper limb function & One DOF & \begin{tabular}{c} **Passive** \\ **Active** \\ \end{tabular} & One DOF that provides linear \\ \hline ARMin & Upper limb rehabilitation & Seven & Passive & \begin{tabular}{c} **Robot has no** \\ **sharp edges.** \\ \end{tabular} \\ \hline ARMin & Upper limb rehabilitation & Five DOF & Active & \begin{tabular}{c} **Robot has several** \\ **positions sensors.** \\ \end{tabular} \\ \hline CADEN-7 & Upper limb rehabilitation & Five DOF & Active & \begin{tabular}{c} **Three levels of safety:** \\ **mechanical, electrical and** \\ \end{tabular} \\ \hline L-EXOS & Upper limb rehabilitation & Five DOF & Active & \begin{tabular}{c} **Maximum velocity is** \\ **10 rpm.** \\ **Maximum torque is** \\ \end{tabular} \\ \hline T-Wrex & Upper limb rehabilitation & Five DOF & Active & \begin{tabular}{c} **Positions sensors and custom** \\ **grip sensors** \\ \end{tabular} \\ \hline REHAROB & \begin{tabular}{c} Upper limb rehabilitation \\ (Shoulder and Elbow) \\ \end{tabular} & \begin{tabular}{c} Three \\ **DOF** \\ \end{tabular} & Passive & \
\begin{tabular}{c} **Sensors to control and monitor** \\ **the generated forces.** \\ \end{tabular} \\ \hline BONES & Upper limb rehabilitation & Four DOF & Active &
\begin{tabular}{c} One extra actuator is added \\ for safety issues. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 3: Characteristics of the rehabilitation robots. DOF: degrees of freedom, MIME: mirror image movement enabler, ARM: Assisted Rehabilitation and Measurement, CADEN-7: cable actuated dexterous exoskeleton for neuro-rehabilitation with seven degrees of freedom, T-Wrex: therapy Wilmington exoskeleton and BONES: Biomimetic Orthosis for Neurorehabilitation.