Coaching system feedback

For instructional feedback, the keypoint of the human body was estimated using the Mediapipe algorithm [38]. We extracted body landmarks of each of the keypoints to enable angle calculation of each body joint, e.g., left/right shoulder, left/right elbow, left/right wrist, left/right hip, left/right knee, and left/right ankle. In order to provide instructions for incorrect posture, each joint angle was calculated from three points using Eq. 5.

Where c, b, and a is the first, middle, and last point of the three-point, respectively. And it used to identify the angle at this point.

In the yoga coaching system process, yoga posture recognition was predicted based on 14 different yoga postures. When the user performs an incorrect posture following the selected yoga image guide, the joint angle is calculated based on keypoints estimated through utilizing the angle-checking condition. Figure 4 shows the process flow of the real-time yoga coaching system used in this study.

Real-time coaching feedback flowchart of yoga self-coaching system