# Applying Vision-Based Pose Estimation in a Telerehabilitation Application
## 4 Conclusions  
This paper studies the feasibility of applying 2D body pose estimation to the development of augmented reality exergames. To that end, the ExerCam application was developed. It works as an augmented reality mirror that overlays virtual objects on images captured by a webcam. As advantages of the proposal compared to other works discussed in Section 1, ExerCam is a new telerehabilitation system for patients and therapists. Patients can perform therapy from home using a laptop and perform the tasks and exercises programmed by therapists. Therapists, in turn, can carry out a continuous and remote evaluation of the evolution of the patients. With a 3D system, patient information and monitor movements in game mode can be acquired more accurately, but then, a more complex system would be needed. The novelty of the system resides in the use of a low-cost 2D vision system for the estimation of the human pose to be able to obtain an application of augmented reality mirror type. ExerCam can be executed on a laptop (even in the future on a Tablet) without advanced devices so it becomes an accessible system for most people. On the other hand, it has been possible to adapt a series of exercises proposed with a gamified scene, which avoids the feeling of monotony and boredom of traditional rehabilitation and motivates the participants to continue performing therapy at home. Its use in specific medical conditions has not been studied, although the accuracy of the calculation of the ROM through ExerCam has been demonstrated. However, the application allows the creation of tasks that could promote physical exercise and gross motor skills. As indicated in Section 3.1, in this first study, a distance of ten degrees between targets was chosen for the tasks in the task mode. This choice will be in the hands of the therapist who prescribes the tasks; however, for these first tests, 10 degrees was chosen, as the maximum standardized error for ROM calculation applications is usually 12 degrees. This way, one can obtain a maximum of 10 degrees of error in the ROM calculation applications in task mode parting from the target positions. If the distance between targets is decreased (or increased) to 5 degrees, we would have a maximum error of five degrees in task mode with targets. It is important to note that the ROM calculation with the highest precision obtained with ExerCam is obtained, as expected, with the ROM value from the variation of the joint coordinates. Figure 11: Score per participant obtained by SUS test. Figure 10: Adjectives associated with the raw scores of SUS test. In the results obtained from the calculation of the ROM using the variation of the joint, the measurement error committed by ExerCam is less than 3%, so the system is valid as a resource for measuring and evaluating the evolution of participants. It should also be taken into account that in manual measurements, there is a bias error such that, as the sample number increases, this error tends to decrease [51]. ExerCam, as well as other exergames, is an application oriented toward users, and as such, experience and satisfaction are important factors to take into account. For that reason, after the execution of the exercises, the SUS questionnaire was given to the participants and therapist, allowing them to assess the usability of the system from the perspective of the user. In the results of the questionnaire, shown in Tables 6 and 7, it can be observed that most of the users answered that the application was easy to use (with Items I2, I3 and I8 having scores greater than 4). According to I7, most of the participants think that other people would be able to learn to use the application quickly. From answers to I10, they do not think that it is necessary to acquire new knowledge or skills in order to use the application properly. According to I5 and I6, participants also think that the application is well engineered.