###### Abstract  
Virtual environments (VEs) and haptic devices increase patients' motivation. Furthermore, they observe their performance during rehabilitation. However, some of these technologies present disadvantages because they do not consider therapists' needs and experience. This research presents the development and usability evaluation of an upper limb rehabilitation system based on a user-centered design approach for patients with moderate or mild stroke that can perform active rehabilitation. The system consists of a virtual environment with four virtual scenarios and a developed haptic device with vibrotactile feedback, and it can be visualized using a monitor or a Head-Mounted Display (HMD). Two evaluations were carried out; in the first one, five therapists evaluated the system's usability using a monitor through the System Usability Scale, the user experience with the AttrakDiff questionnaire, and the functionality with customized items. As a result of these tests, improvements were made to the system. The second evaluation was carried out by ten volunteers who evaluated the usability, user experience, and performance with a monitor and HMD. A comparison of the therapist and volunteer scores has shown an increase in the usability evaluation (from 78 to >85), the hedonic score rose from 0.6 to 2.23, the pragmatic qualities from 1.25 to 2.20, and the attractiveness from 1.3 to 2.95. Additionally, the haptic device and the VE showed no relevant difference between their performance when using a monitor or HMD. The results show that the proposed system has the characteristics to be a helpful tool for therapists and upper limb rehabilitation. rehabilitation; virtual environment; user-centered design; user experience +
Footnote †: journal: Medicallimb (UL) remain for many stroke survivors; only 5% regain full function, and 20% remain nonfunctional [1,5,6]. In general, motor rehabilitation is focused on improving the function affected by pathologies or caused by injuries to allow patients to perform daily living activities [7,8]. To observe a change in the UL movement after a stroke, it is essential to take into account the repetition of exercises and the patient's motivation in traditional rehabilitation [9,10]. However, sometimes the repetition of exercises is monotonous and boring, and patients may lose motivation, and this is finally reflected in the success of the rehabilitation [9,11]. Post-stroke rehabilitation exercises allow reorganization of neural networks in the brain and nervous system, which is known as neuroplasticity [12]. Up to now, the use of new technology, like virtual reality (VR) or virtual environments (VE), has been shown to have a positive effect in different medical areas, such as in the reduction of anxiety and stress [13], physical activity coaching for older adults [14], for presurgical tasks [15] and for rehabilitation [16,17]. VR is a simulation or model created with computer modeling. It allows the user to interact with a 3D environment [18]; on the other hand, VE refers to graphical scenarios where the users interact with virtual objects simulating reality [8]. This technology has benefits, for example, the frequency and intensity of exercise can increase compared with standard approaches, and the motivation and engagement increment for repetitive tasks [19]. To enhance the interaction between the system and the user, the use of a haptic device is useful, as it allows the reduction of mental effort and cognitive load, and it also decreases the time to perform a task and the number of collisions with a virtual object through the generation of haptic feedback [20]. This allows the user to interact with virtual objects through a feeling of touching and manipulating [21], according to the haptic type, the user can feel the texture, temperature, vibration, weight, or inertia of an object [22].