## 6 Components Reliability and Usability  
While not focused on such goal, the experiments described in the previous sections also tested the reliability of the proposed components, ECA and 6-DoF SMC in particular, on the user experience level. During the E.ECA experiments with ECA turned on, one experimentalist watched the ECA dashboard on the SRV. As the dashboard was displaying the table with the actual positions of the avatars and the virtual scene, he was able to compare the position coordinates, captured by ECA, with the positions of avatars in the scene. No visible differences were observed. The 6-DoF SMC was permanently employed during the E.6 DF experiments with the component turned on. The component was performing without problems and translated the experimentalist movement in the real world to the avatar movement in the virtual scene reliably. During the E.HL experiments, the experimentalist walking with MS HoloLens occasionally performed hand movements in the MS HoloLens field of view to stimulate the HoloGOM component. However, to make the user activity with MS HoloLens similar to the activities of users with other devices (PH and PC), we did not include any gesture-involving tasks. The reliability of the gesture recognition was tested separately, in a modified version of the scene from Figure 7. The scene included two movable blocks: a blue block, movable by the dynamic gesture (tap-and-drag), and a brown block, movable by the click-and-push gesture. An experimentalist was moving the blocks using the gestures. Each gesture was successfully performed 60 times. The modified scene is available at [[https://lrikiggcve.herokuapp.com/hololens.html](https://lrikiggcve.herokuapp.com/hololens.html)]([https://lrikiggcve.herokuapp.com/hololens.html](https://lrikiggcve.herokuapp.com/hololens.html)) (accessed on 22 April 2021). Because it is adjusted to MS HoloLens, it is not possible to move in it or manipulate with the blocks when opened on other devices. The same scene was used for user experience testing of HoloGOM with eight participants. The MS HoloLens device with the scene loaded was provided to them, and they were asked to move the blocks using the corresponding gestures. After performing the task, they filled in the standard System Usability Scale (SUS) questionnaire [33]. During the testing, one of the authors was available to explain the task to the participants and assist them. The participants were aged from 24 to 54 years, and there were six men and two women. The resulting SUS score was 66.56, which is slightly below the average (68, according to [PERSON] [34]). When asked, all the users selected the dynamic gesture (tap-and-drag) as the more suitable one. This was because the block was visible during the movement, so the users were sure that they were performing the movement correctly. Some of them suggested implementing visual feedback for the tap gesture to improve the situation. One of the reasons behind our decision to focus on web-based XR was the easiness of making shared virtual environments available to potential users. Just by providing a link to the environment and a set of instructions, arbitrary users can utilize the environment in a proper way. A promising scenario, outlined in [10], is a testing of virtual prototypes of autonomous devices. In such case, a shared scene is used as a testing area, where one client app takes the role of the tested prototype and real persons, using their client apps, act as testers. Thanks to the ECA component, the client app representing the prototype can be aware of the testers and react to their actions. To test usability of such scenario when implemented with A-Frame, NAF and ECA, we prepared a shared virtual scene with an autonomous robot, which cleans positions marked with red tiles. The robot reacts to other users by avoiding them when moving or by interrupting the cleaning process.