“…Performance score = ∑k = 1s[1−C(sik, tjk)90×8]s = 1−DTW(S, T)90×8×s, where s is the length of optimal warping path, 8 stands for eight bone vectors selected for motion evaluation, and C ( s ik , t jk ) is the element of optimal warping path in the cost matrix, which is the summation of angle differences for eight bone vectors, and DTW distance- DTW ( S , T ) is a summation of elements ( C ( s ik , t jk )) along the optimal path. We assume the angle difference between two corresponding bone vectors is within 90 degrees based on an earlier study [18], which results in the maximum DTW ( S , T ) along the optimal path, which would be 90 × 8 × s. Because the output distance ( DTW ( S , T )) is a measure of dissimilarity between the two motion time series (the longer the distance, the greater the deviation), the last part of Equation (4) would be a percentage score (0–100%) to measure the level of similarity between the trainee’s motion and trainer’s motion.…”