# Telehealth Using PoseNet-Based System for In-Home Rehabilitation
## 2 Related Work  
Various rehabilitation systems or applications have been currently developed, such as the virtual reality and motion-based games [16]. As a result, these applications have attracted great attention and interest among researchers. These applications motivate patients to move their body parts more frequently and offer patients a sense of accomplishment through an interactive user interface. Patients will need to follow the step-by-step rehabilitation exercises as guided by a 3D avatar or by following the recorded instructional video by the professional physician. [PERSON] et al., [PERSON] et al., [PERSON] et al., [PERSON] et al. and [PERSON] et al. [16; 17; 18; 19; 20] presented a Kinect-based rehabilitation system by integrating different approaches. Research in [16; 17; 18] focuses on integrating a 3D avatar for rehabilitation exercises. The system matches the patients' movements with the benchmark movements of a 3D avatar to determine the accuracy of the posture. The authors in [16] determine the accuracy of the posture by measuring the differences between the 3D angle of the joints and limbs. After the comparison, the system will display five different messages, namely \"Execute the movement (has reached the initial position and has to execute the movement)\", \"Execute posture (very far from reaching the next posture)\", \"Cool, cool (about to reach the position)\", \"You're close (very close to the position)\", \"Correct (posture is correct)\". The authors of [17; 18] adopt the dynamic time warping (DTW) approach to calculate the optimal warping distance in order to measure the similarity between two motion sequences. The optimal warping distance is then converted to a performance score (0-100%) to show the similarity between the patient's and the 3D avatar's movement. Research in [19; 20] adopts a recorded instructional video to guide patients to perform rehabilitation exercises at home. The patients need to follow the exercises as guided by a physician in the recorded instructional video. After completing the rehabilitation exercises, joint distance is calculated in [19] based on the captured patient's skeleton keypoints and the law of cosine is applied to calculate the angle differences between patients' movement and the standard movement of the physician. A quantitative score is then provided by dividing the score into four levels of comments, namely \"Try it again\", \"Good Work\", \"Excellent\" and \"Perfect\". On the contrary, the research in [20] integrated DTW with Euclidean distance and fuzzy logic to convert the optimal warping distance to three performance levels, namely \"Bad\", \"Good\" and \"Excellent\", to determine the accuracy of the posture. Four sets of the Kinect-based rehabilitation system were presented in [21; 22; 23; 24]. These research papers were published based on a project that was designed to focus on patients who usually suffer from movement disorders and neurological disorders that require in-home rehabilitation. The system in [21] presents a virtual trainer for patients to imitate movements during the rehabilitation exercises. Based on the 2D keypoints obtained from the hands and legs of patients, the joint angle is calculated by using the law of cosine. The calculated joint angle is then used to compare with the benchmark joint angle of the virtual trainer to evaluate the deviation of the patients' movement angle. On the other hand, researchers in [22; 23; 24] designed a video game for rehabilitation exercises with the aim of increasing the motivation of patients to perform in-home rehabilitation. These three papers offer several rehabilitation games that require the use of virtual movements to control the games. The patients need to move their bodies and perform a series of specific movements to achieve the goal. This is also beneficial for patients because they exercise their bodies more often while playing. Researchers in [22; 23] implement games based on different difficulty levels to monitor patients' progress.