Haptic-based Virtual Reality (VR) applications have many merits. What is still obscure, from the designer's perspective of these applications, is the experience the users will undergo when they use the VR system. Quality of Experience (QoE) is an evaluation metric from the user's perspective that unfortunately has received limited attention from the research community. Assessing the QoE of VR applications reflects the amount of overall satisfaction and benefits gained from the application in addition to laying the foundation for ideal user-centric design in the future. In this article, we propose a taxonomy for the evaluation of QoE for multimedia applications and in particular VR applications. We model this taxonomy using a Fuzzy logic Inference System (FIS) to quantitatively measure the QoE of haptic virtual environments. We build and test our FIS by conducting a users' study analysis to evaluate the QoE of a haptic game application. Our results demonstrate that the proposed FIS model reflects the user's estimation of the application's quality significantly with low error and hence is suited for QoE evaluation.

Undesired physical fatigue reduces the overall Quality of Experience (QoE) of virtual reality haptics applications. Detecting fatigue is the first step in rectifying this problem. Fatigue in usability analysis is usually detected through conducting questionnaires and observations. This paper introduces an objective indirect discovery of user's fatigue through analyzing data of a haptic writing application. Our results show that if users are feeling tired their kinetic energy would decrease. We can compute this kinetic energy from the velocity of the arm movement during the usage of the haptic device.