**5. Conclusions**

Torque monitoring system was successfully implemented in the control of the ASPIRE robotic system. The development of the system started from the requests identified during the clinical trials performed in the fall of 2019 in Cluj-Napoca. A series of effects that may influence the effectiveness of the rehabilitation were presented and torque control proved to be a solution in identifying and overcoming some of these effects. After the development of the torque control system the performance was tested using healthy subjects chosen among the staff of the research center. The results have validated the functionality of the proposed improved control system and pushed the development of the experimental model towards the next level of maturity, preparing it for further clinical trials. At the same time the torque-based control adds to patient safety and the possibility to improve the HRI characteristics of the robotic system with high levels of safety and user-friendliness.

**Author Contributions:** Conceptualization, D.P., P.T., C.V., G.B. and G.C.; Data curation, D.T., N.T., I.D.G. and C.A.; Formal analysis, N.P.; Investigation, D.T., P.T., N.T., C.V., I.D.G., G.B., C.A. and G.C.; Methodology, I.D.G., G.B., G.C. and N.P.; Project administration, D.P.; Resources, D.T.; Software, G.B.; Validation, C.V.; Writing—original draft, D.P. and P.T.; Writing—review and editing, P.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by a gran<sup>t</sup> from the Romanian Ministry of Research and Innovation, CCCDI—UEFISCDI, project number PN-III-P2-2.1-PED-2019-3022/546PED/2020 (NeuroAssist) within PNCDI III, and by the project POCU/380/6/13/123927—ANTREDOC, "Entrepreneurial competencies and excellence research in doctoral and postdoctoral studies programs", co-funded from the European Social Fund through the Human Capital Operational Program 2014–2020.

**Institutional Review Board Statement:** Ethical review and approval were waived for this study, due to the fact that the validation tests were intended only to assess the feasibility and range of motion of ASPIRE for the rehabilitation of the upper limb, being achieved in laboratory conditions, which required the participation of volunteers, healthy subjects. Furthermore, the volunteers have given their written consent after being informed about the test circumstances and the robotic system's operation, as well as any hazards or safety concerns that may arise during the tests.

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The data presented in this study are openly available in reference number [37,39–41].

**Conflicts of Interest:** The authors declare no conflict of interest.
