**3.2 Results**

*Assistive and Rehabilitation Engineering*

**system**

In addition, it has been observed in the development of the tests that 18% of the time, the patients perform correctly an exercise with respect to the angle and only 27% do it at an acceptable speed during its execution. On the other hand, the detec-

**3. An iterative method to improve the usability of the telerehabilitation** 

Usability refers to the degree to which a product can be used to achieve goals in a specific context of use [9]. A software product that has not gone through a process of usability evaluation will not guarantee that users take advantage of the qualities and the benefits of the application. To prevent users from leaving the telerehabilitation

Several studies have highlighted the main advantages of combining heuristic evaluation and cognitive method for usability assessment [10–13], among them: facility of interaction with the interfaces, immediacy of the response, non-intrusive methods, time or means are not expensive, these tests can be done inside a laboratory, good for the requirements refining, does not involve end users, does not require a fully functional prototype, does not require advance planning, applicable

Other studies [12, 14] presented the results of the usability evaluation carried out on the iterative design of the prototypes, obtaining advantages such as facilitating future actions of the end users and improving the learning and development processes. However, the authors said that an online prototype has several drawbacks since it still presents only part of the final version and a limited one in terms of colors and interactive elements. The previous studies do not systematically present the evolution of usability, through an orderly and cyclical process. In addition, these studies do not show that it is possible to improve the use of telerehabilitation

An experiment was carried out to understand the perceived usability for the ePHoRt platform and to determine a baseline on which to initiate the process of iterative usability improvement of the platform. **Figure 12** shows one on the main interfaces of the platform. The experiment began with 23 participants in an age

tion time is 0.0045 s while training and 0.002 s in the testing phase.

platform, it is necessary to carry out exhaustive evaluations of usability.

to the stages of design, coding, testing, and implementation of software.

platforms without endangering patient safety.

**3.1 Experimental design**

**82**

**Figure 12.**

*ePHoRT active exercise interface.*

The research results showed improvements in usability through four iterations. Each of the iterations contributed with a list of improvements that were implemented according to the severity level.

In the first iteration, the experts found 39 heuristic violations; these violations were distributed as follows: 12 of high severity, 16 of medium severity, and 11 of low severity. The heuristics with higher incidence and severity were visibility of system status, help and documentation, feedback, and extraordinary users.

In the second iteration, the number of usability problems decreased. However, two atypical cases were presented: (1) increase in the number of usability problems for heuristic "user control and freedom" and heuristic "physical constraint" and (2) the number of usability problems that did not vary for the heuristic "match between the system and the real world" and heuristic "aesthetic and minimalist design."

In the third iteration, 14 mock-ups were designed considering the comments of the previous iterations. In the heuristic evaluation, there were a total of 92 heuristic violations. Experts reported that eight interfaces (57.14%) did not achieve the appropriate feedback for users. Therefore, the platform incurred a clear violation of the heuristic "visibility of system status." In addition, of these eight interfaces, the experts reported the heuristic violation of "help and documentation" on the Login interface and the password reset interface. Finally, experts considered that 42.86% of the interfaces (six) were not flexible or efficient in use.

In the fourth iteration, 17 mock-ups were designed, incorporating the observations from the previous iteration. The experts reported a total of 364 heuristic violations. However, the questionnaire interface had only three low-severity usability problems. This value had been decreasing in severity throughout the evaluation process. The experts assigned greater importance to the following interfaces: questionnaire, acute rehabilitation, active exercise (1/3); acute rehabilitation, active exercise (2/3); acute rehabilitation, active exercise (3/3); and acute rehabilitation, learn (1/5) interfaces.
