## 4 Discussion  
We described the implementation and the evolution over the years of an interactive, computer-based system based on real-time image processing, which reacts to movements of a human body with graphics and sound. Looking at the three systems presented it is clear how we are trying to move towards the realization of a complete system, that on the one hand is user friendly to the children, giving him/her the impression of participating in a game, on the other hand, it is accurate enough to useful for a psychological assessment as accurate as possible. The third version, SEMI project, developed a set of interactive games organized by levels of difficulty, taking account of the sensory profile of every single child involved. In particular, the prototype has been thought to improve gross and fine motor skills and the enhancement of imitative aspects to foster social interaction and personal autonomy of the child. The children involved in the project were all in charge of weekly rehabilitation treatments in a specialized rehabilitation center, followed by several specialists. All the results have been encouraging, all the children have faced the experimentation with enthusiasm and, during the sessions, all showed improvements in attention and response time. The evaluation has increased the score in almost all aspects considered, and particularly those related to motor coordination. In the children who participated in the experiment, compared to the control group, an improvement in balancing tests and in hands-movement testing was found. Extrapolated overall trends reported progressive improvement in the children' skills. The use of this instrumentation has allowed children to perform exercises in a motivating and enjoyable climate. A high level of acceptance by professionals was observed and parents' feedback was also extremely positive. The models used seem to be promising tools to improve emotional and social skills. Figure 10: Progress of “guess the movements” exercise. In addition, all the children in the sessions showed greater ability to self-control the movement as well as the ability to select specific motor areas. Analyzing the results, we need to consider some limitations of the study, for example the small sample size. The study was conceived substantially as a feasibility study so only a limited number of patients were recruited. The results of the study should be replicated in a larger sample to demonstrate possible application in a clinical scenario. A more complete sample will also allow to evaluate how different the response can be with different types of children with ASD. Finally, the effects of external factors (e.g., family involvement and health conditions) that may have influenced the improvements found were not considered. Further studies must be carry on by our research group to improve the system. Disadvantages of the proposed system, raised during the experimentation were the following:  
* given the broad spectrum of ASD there is a need to design a person specific intervention protocol;
* the need for trained therapists and the economic cost of such treatments;
* parent training and regular monitoring to check whether the parents properly implement the intervention protocol;
* For the exploratory nature of the design this was a feasibility study aimed to assess the usefulness and acceptability of the platform, further elaboration has to be carry on for a clinical validation;
* the proposed system has to prove its ability of generalization to everyday life. We are continuing our experiments using Microsoft Kinect v.2 and other gestural interfaces like the Leap Motion, more suitable for fine motor praxis dysfunction. We also started to experiment with Virtual Reality based systems. VR has become a popular platform used in ASD interventions and research has delivered successful results in areas including social and cognitive training exercises [46]. Virtual reality enabled training for social adaptation for school-aged children with ASD [47].