The quantitative result of comparison (Table 3) shows that trajectories of our model presents less deviations from the ground-truth data than the model in11. This is mainly caused by the linear feature of the PD servo. We also notice that the peak values of the trajectories of the previous model11 are generally higher than the ones of the proposed model in this work. The reason is possibly caused by the fact of over-shooting34. The problem of over-shooting refers to the fact that the PD servos normally require a large value of kg, thus causing the over-protraction/elevation/extension of the foot.Table 3Quantitative comparison of the trajectory difference between the ground-truth data and the ones generated by our model and the previous model11.JointsOur ModelPrevious Model11body-coxa0.71881.4827coxa-femur0.34671.7306femur-tibia0.49624.1081