## 5 Experimental Results and Contributions
### Monitoring and Information Display System
#### 5.1.1 Virtual Reality System  
The virtual reality system, as well as the 3D model representation system used in the proposed system, is based on the Unity3D development environment. The integration of VR technology into the system is aimed at achieving the following objectives:  
* offer more advanced rehabilitation methods as an alternative to traditional therapy, thus maximizing the effect of the rehabilitation measures;
* allow patients to perform actions that they are not able to do in real life due to their disabilities;provide individualized treatment plans developed based on careful assessment and following the treatment goals of each case;
* increase patient commitment and motivation with virtual environments where the tasks to be performed are simulated;
* provide immediate and illustrative feedback;
* improve the results by measuring and analyzing different data related to the user's actions; and
* provide a controlled environment through a dynamic environment that can be managed according to certain conditions as well as actions taken by the user. However, when designing a VR environment dedicated to the rehabilitation, there are several aspects [42] to be considered before the tool is developed to make it suitable for users, where the similarity of the scenes in these environments to those in video games is highlighted. The aspects to be taken into account are the following:  
* **Award**: According to the body of research on the neuroscience of reward and motivation, the limbic system, in particular the Nucleus Accumbens (NA), is critical for learning new behaviors, especially those associated with reward-seeking, pleasure, and addiction. Activity in NA has been shown to scale linearly to the likelihood of receiving a reward, and differences in NA activity correlate with individual differences in sensation-seeking. * **Difficulty**: It is important to consider difficulty as an interaction of individual and environmental limitations to understand how difficulties might arise directly from an injury/illness or from the changes that accompany these individual changes. Skill transfer is particularly important for rehabilitation, where skills acquired in play are expected to be transferred to activities of daily living. * **Feedback**: Feedback can be used to achieve better long-term retention of the developed skill. However, positive feedback must be given more often to efficiently influence the developed skill. * **Interaction**: The user's interaction with the system increases the user's connection with the virtual environment. The exploration of new stimuli and new environments is strongly associated with physiological rewards. * **Clear objectives and mechanics**: Goal-directed tasks lead to a higher probability of acceptance of assistive devices. Lack of objectives and instructions can have a significant negative impact on patient motivation. Therefore, therapeutic goals that are not clear to patients can compromise the recovery process. Patients with high motivation in a rehabilitation setting reported communicating more actively with their therapist, and being clear and consistent in the instructions given to the patient created a sense of comfort in knowing that they were progressing towards their therapy goals. Unclear instructions caused patients to become confused and frustrated and eventually lowered their motivation. This VR system is integrated through the Oculus Quest device [43] to allow interaction with different VR scenarios where the user performs different exercises. The diagram shown in Figure 4 shows the main components related to the representation of the VR scenario together with the information exchange. Figure 4: Main components of the virtual reality environment. The system implemented allows the patient to receive instructions for each of the exercises, both visually and acoustically, and to observe which movements must be performed to achieve the objective of the exercise.