## 5 Conclusions  
The use of new technologies in the rehabilitation field has increased in the last years. Robot aided and VR rehabilitation provide higher motivational environments to the patient, facilitate the performance of the necessary movement repetitions for inducing the UL motor learning and increase the amount of therapy that patients receive. However, these technologies are expensive, and a need for low-cost devices exists. This work takes advantage of low-cost VR systems and robotic haptic devices to enhance involvement and engagement of patients to provide a congruent multisensory afferent feedback during motor exercises and benefit from the flexibility of virtual scenarios.  
The low cost platform developed in the present work enables the UL rehabilitation with haptic feedback and EMG monitoring for SCI patients. First of all, three serious games have been designed and implemented to compute within them the smoothness movement. The design and implementation of each serious game required the definition of a unique interface and physical models related to haptic feedback. In all of them, the movement smoothness has been reported lower in patients than in healthy people, showing an inverse relation with the peaks number obtained. As a conclusion, the three serious games proposed are suitable for measuring movement smoothness, but the most suitable game for discriminating between healthy and SCI patients is the \"Following the path\" game. This is because, in this game, the order to reach the different nodes has been imposed, being always the same and allowing an identical comparison between participants. Nonetheless, these assumptions should be confirmed with a large clinical validation.  
A proof of concept to check the functionality of the platform with SCI patients was made. Results obtained in terms of movement smoothness show differences in the movement patterns. Some benefits drawn from this research are exposed as follows:  
* All the devices of the platform are low-cost and easily adaptable for different people, with a short time spent in preparation for the serious games performance.
* The configuration options used in this research allow to create different virtual scenarios, in order to personalize each patient rehabilitation.
* The final design generates a good haptic response and reliable monitoring of the muscle contractions.  
Conceptualization, A.G., D.S.-M. and A.d.l.R.G.; methodology, A.G., D.S.-M., A.d.l.R.G.; software, D.S.-M.; validation, D.S.-M., A.d.l.R.G., and A.G.-A.; formal analysis, A.d.l.R.G., A.G.; investigation, D.S.-M., A.d.l.R.G.; resources, A.G. and A.G.-A.; data curation, D.S.-M. and A.d.l.R.G.; writing--original draft preparation, A.G., D.S.-M. and A.d.l.R.G.; writing--review and editing, A.G., A.d.l.R.G. and A.G.-A.; visualization, A.G., A.d.l.R.G.; supervision, A.G., A.d.l.R.G.; project administration, A.G.-A. and A.d.l.R.G.; funding acquisition, A.G. and A.d.l.R.G. All authors have read and agreed to the published version of the manuscript.  
This research has been funded by grant from the Spanish Ministry of Economy and Competitivity and co-funded from FEDER, National Plan for Scientific and Technological Research and Innovation. Project RehabHand (Plattadform de bajo ceste para rehabilitacion del miembro superior basado en Realidad Virtual, ref. DPI2016-77167-R). This work was supported by the National Hospital for Paraplegics in Toledo (Spain) and the Universidad Politecnica de Madrid (Spain). The authors acknowledge the collaboration of the participants in this study.  
The authors declare no conflict of interest.