# Quasi-Passive Resistive Exosuit for Space Activities: Proof of Concept
## 5 Conclusions  
We performed the assessment of the resistive exosuit with QPA and specific sensors strategy during five repetitions of walking tasks by analyzing the effects on gait kinematics, muscular activation and muscular fatigue. The subsystem and overall validations underline that the actuation typology (QPA) and soft sensor technology perform well and are very promising even if considering the challenge offered by the space environment. While a statistically relevant study was outside the scope of this preliminary assessment study, these results are very promising and point toward positive findings overall. The results of this study, which underline an effective increase in both muscular activation and muscular fatigue, confirm the ability of exosuit to significantly increase the muscular effort necessary to perform simple cyclical and repetitive tasks. This implies that in zero gravity the same swing of the knees may require a fatigue comparable to that required to walk on earth, thus allowing the use of this device for continuous daily training in micro-gravity. In addition, this study shows a further usage of the XoSoft platform, that apart from gait assistance, it can be used as resistive device for training and physical exercise, particularly for medium and long endurance spaceflights. This preliminary work will prompt further investigation and development targeting the space community and related issues.  
Further studies on the resistive exosuit will be conducted to validate the effectiveness of the exosuit on different physical exercises. Further improvements to the exoskeleton will aim to develop a full-body exosuit able to training all the main muscle/joint groupings, sensor solutions to measure a user's angular joint, control strategies to ensure suitable operations in a micro-gravity environment, and the development of a low energy consumption QPA.  
Conceptualization, C.D.N.; methodology, C.D.N.; software, C.D.N., M.T. and J.S.L.-M.; validation, C.D.N., G.C. and M.T.; formal analysis, C.D.N. and G.C.; investigation, C.D.N.; resources, D.G.C. and G.V.; data curation, C.D.N. and G.C.; writing--original draft preparation,C.D.N.; writing--review and editing, C.D.N., G.C., M.T. and D.G.C.; visualization, C.D.N., G.C. and M.T.; supervision, L.B., E.R. and J.O.; project administration, J.O. All authors have read and agreed to the published version of the manuscript.  
This work has received funding from the European Union's Horizon 2020 framework programme for research and innovation under grant agreement No 688175; and the European Space Agency (ESA). J.S.L.M. was in receipt of a Training Program for Academic Staff fellowship (FPU16/01313) by the Ministry of Universities of the Government of Spain.  
The study was conducted according to the guidelines of the Declaration of Helsinki, and these tests are compiled with the experimental protocol approved by the Ethical Committee of Liguria, Italy, 8 October 2019, protocol number: 001/2019.  
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.  
The authors declare no conflict of interest.