# Modular Design and Decentralized Control of the Recupera Exoskeleton for Stroke Rehabilitation
## 5 Conclusions  
This paper presents an overview of the novel Recupera exoskeleton for stroke rehabilitation applications. Modularity and decentralized control are two driving themes in the design and hence they are reflected in all aspects of mechanical, electronic and software design. This allows for easy integration and unit-testing of individual subsystems and various levels of safety implementation. The use of novel parallel mechanisms helps in achieving a lightweight design with good dynamic characteristics. By this together with different rehabilitation therapies such as Teach & Replay and Mirror therapy (see System Overview Video ([[https://www.youtube.com/watch?v=Rln0](https://www.youtube.com/watch?v=Rln0) ASTmW6g]([https://www.youtube.com/watch?v=Rln0](https://www.youtube.com/watch?v=Rln0) ASTmW6g)), Patient Test Video ([[https://www.youtube.com/watch?v=dCnltkzbpZ8](https://www.youtube.com/watch?v=dCnltkzbpZ8)]([https://www.youtube.com/watch?v=dCnltkzbpZ8](https://www.youtube.com/watch?v=dCnltkzbpZ8)))) the system can be applied to patients with different demands, enables mobile support as well as self-training during hospital stay or at home. One major drawback of the present setup is the lack of force/torque sensors in the linear drives used in the spine hexapod and legs. Since, these drives have high friction which is difficult  
\begin{table}
\begin{tabular}{r c c c c c} \hline \hline
**Device** & **Recupera** & **Harmony [31]** & **ARMIN III [29]** & **SUEFUL-6 [33]** & **ADL [31; 43]** \\ \hline Weight (kg) & 8.6 & 31.2 & 18.75 & - & - \\ DOF & 10 & 14 & 4 & 6 & - \\ Bilateral & yes & yes & no & no & - \\ Torso harness & yes & yes & no & no & - \\ Gripper & yes & no & no & no & - \\ Wheelchair & yes & no & no & yes & - \\ \hline Ab./Adduct. (\({}^{\circ}\), Nm) & 87/40(28) & 170/60(34) & 135/47(39) & - & 131/54 \\ Ex./Int. rot. (\({}^{\circ}\), Nm) & 40/75(14) & 79/80(34) & 91/92(33) & 0/90(35) & 76/62 \\ Flex./Ext. (\({}^{\circ}\), Nm) & 170/30(28) & 160/45(34) & 140/46(38) & 0/90(9) & 131/51 \\ Elbow flex. (\({}^{\circ}\), Nm) & 102(9) & 150(13) & 123(32) & 120(9) & 148 \\ Pro/supinat. (\({}^{\circ}\), Nm) & 108(1) & 172(1.25) & - & 140(4) & 167 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Comparison of Recupera upperbody system to other upper body exoskeletons and the Activities of Daily Living (ADL) ROM.  
Figure 19: Sitting and Standing with Recupera full body exoskeleton.  
to model, the force control is not possible over direct current measurement. The system is currently being upgraded with direct force measurement in these drives. This will enable additional mobility features on the system such as active balancing and walking. Furthermore, although the system offers the possibility to enhance the control using biosignal-based control as discussed in [36; 50; 57], these aspects have not been evaluated in depth. Accordingly, in future we will evaluate the effect of biosignals on the control of the system and the effectiveness in stroke therapy.  
The following are available online at [[http://www.mdpi.com/2076-3417/9/4/626/s1](http://www.mdpi.com/2076-3417/9/4/626/s1)]([http://www.mdpi.com/2076-3417/9/4/626/s1](http://www.mdpi.com/2076-3417/9/4/626/s1))  
All authors designed and implemented the system. [PERSON] and [PERSON] developed the concept and designed the experiments of the paper. [PERSON], [PERSON] and [PERSON] developed the software and firmware. [PERSON], [PERSON] and [PERSON] performed the experiments and analyzed the results. [PERSON], [PERSON], [PERSON], [PERSON], E.A.K. and F.K. prepared the manuscript. All authors reviewed and edited the manuscript.  
Federal Ministry of Education and Research (BMBF, grant no. 01 IM14006A).  
We thank [PERSON], [PERSON], and [PERSON] for their valuable input to the design of the exoskeleton. We also thank [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] for their valuable input and help during the development of the system.  
The authors declare no conflict of interest.