## 1 Introduction  
Recently, combining wireless communication with other fields' research is an important issue since the technological development changes suddenly. Intelligent medical is one of the interdisciplinary fields whose research is combining medical with information communication techniques. In the existing medical treatments, the rehabilitation treatment often needed more medical resources since the physician, nurse, and physical therapist were all required in the process of rehabilitation treatment. The numbers of people with rehabilitation symptoms were in proportion to the age. The age of people with rehabilitation symptoms was decreased due to advances in medical technology. Hence, the numbers of people with rehabilitation symptoms were increased recently [1, 2, 3]. The treatment of rehabilitation was different based on the different parts of body and symptoms. Some rehabilitation could be treated at home without in-hospital rehabilitation [4, 5, 6, 7, 8, 9, 10, 11]. Among the existing rehabilitation symptoms, elbow joint rehabilitation occurred most often, such as tennis elbow [12, 13, 14]. After discussion with orthopedists, the elbow joint rehabilitation most often occurred and could be executed at home without in-hospital rehabilitation as is the case with other rehabilitation symptoms [15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29]. From a paper survey, to our best knowledge, the existing rehabilitation systems were divided into a visual recognition and non-visual recognition system. In the rehabilitation systems with visual recognition, it was often combined with virtual reality (VR) and motion-sensing [17; 18; 19; 20; 21; 22; 23]. In [17], it integrated the exoskeleton systems with virtual reality (VR) to improve the traditional rehabilitation. The exoskeleton systems were composed of a load cell and a servo motor. The load cell detected the force of rehabilitation. The servo motor supplied the assisted force of rehabilitation and obtained the open angle of rehabilitation. These factors were used as the inputs of VR to perform the rehabilitation exercises with the simulated weight and real weight. In [18], the authors proposed a telerehabilitation combined with VR and Kinect II motion capture sensor for rehabilitation at home. The therapists could monitor and adjust the rehabilitation program of each patient by telerehabilitation, such as a website. The patient did the exercises of rehabilitation by VR and Kinect. The data is logged by the system. Hence, the therapists could examine the status of rehabilitation and adjust the program of rehabilitation for the patients. In [19; 20], the rehabilitation systems were composed of VR and motion-sensing, such as Kinect. The patients did the exercises of rehabilitation based on VR. The motion of rehabilitation was captured by Kinect. In [21; 22], the rehabilitation systems were also composed of VR and motion-sensing, the same as [19; 20]. However, the motion-sensing technology used was by Wii. In [23], the rehabilitation system was only built by Kinect. The patients could know that the action was correct or not and then could adjust the motion by the captured image from Kinect. Although the rehabilitation by VR or motion-sensing could be interactive and interesting, it was still suitable for some patients only. Firstly, it needed the additional hardware cost. Secondly, the user interface was not often friendly since it often needed the additional installation and settings, especially for elder patients. Finally, it required the additional sufficient space for hardware implementation and capturing by motion-sensing. The rehabilitation was thus constricted to be executed in the fixed location without movement to other places. These issues showed that the rehabilitation by VR or motion-sensing could not be applied to all patients. For the non-visual recognition system, it was divided into rehabilitation assistance and rehabilitation detection.