Ground Reference Points in Legged Locomotion: Definitions, Biological Trajectories and Control Implications Export

@article{citeulike:3658499, abstract = {The zero moment point (ZMP), foot rotation indicator (FRI) and centroidal moment pivot (CMP) are important ground reference points used for motion identification and control in biomechanics and legged robotics. In this paper, we study these reference points for normal human walking, and discuss their applicability in legged machine control. Since the FRI was proposed as an indicator of foot rotation, we hypothesize that the FRI will closely track the ZMP in early single support when the foot remains flat on the ground, but will then significantly diverge from the ZMP in late single support as the foot rolls during heel-off. Additionally, since spin angular momentum has been shown to remain small throughout the walking cycle, we hypothesize that the CMP will never leave the ground support base throughout the entire gait cycle, closely tracking the ZMP. We test these hypotheses using a morphologically realistic human model and kinetic and kinematic gait data measured from ten human subjects walking at self-selected speeds. We find that the mean separation distance between the FRI and ZMP during heel-off is within the accuracy of their measurement (0.1\% of foot length). Thus, the FRI point is determined not to be an adequate measure of foot rotational acceleration and a modified FRI point is proposed. Finally, we find that the CMP never leaves the ground support base, and the mean separation distance between the CMP and ZMP is small (14\% of foot length), highlighting how closely the human body regulates spin angular momentum in level ground walking. 10.1177/0278364905058363}, author = {Popovic, Marko B. and Goswami, Ambarish and Herr, Hugh}, booktitle = {The International Journal of Robotics Research}, citeulike-article-id = {3658499}, citeulike-linkout-0 = {http://dx.doi.org/10.1177/0278364905058363}, citeulike-linkout-1 = {http://ijr.sagepub.com/cgi/content/abstract/24/12/1013}, day = {1}, doi = {10.1177/0278364905058363}, journal = {The International Journal of Robotics Research}, month = {December}, number = {12}, pages = {1013--1032}, posted-at = {2008-11-21 22:01:15}, priority = {2}, title = {Ground Reference Points in Legged Locomotion: Definitions, Biological Trajectories and Control Implications}, url = {http://dx.doi.org/10.1177/0278364905058363}, volume = {24}, year = {2005} }

TY - JOUR ID - citeulike:3658499 L3 - citeulike-article-id:3658499 N2 - The zero moment point (ZMP), foot rotation indicator (FRI) and centroidal moment pivot (CMP) are important ground reference points used for motion identification and control in biomechanics and legged robotics. In this paper, we study these reference points for normal human walking, and discuss their applicability in legged machine control. Since the FRI was proposed as an indicator of foot rotation, we hypothesize that the FRI will closely track the ZMP in early single support when the foot remains flat on the ground, but will then significantly diverge from the ZMP in late single support as the foot rolls during heel-off. Additionally, since spin angular momentum has been shown to remain small throughout the walking cycle, we hypothesize that the CMP will never leave the ground support base throughout the entire gait cycle, closely tracking the ZMP. We test these hypotheses using a morphologically realistic human model and kinetic and kinematic gait data measured from ten human subjects walking at self-selected speeds. We find that the mean separation distance between the FRI and ZMP during heel-off is within the accuracy of their measurement (0.1% of foot length). Thus, the FRI point is determined not to be an adequate measure of foot rotational acceleration and a modified FRI point is proposed. Finally, we find that the CMP never leaves the ground support base, and the mean separation distance between the CMP and ZMP is small (14% of foot length), highlighting how closely the human body regulates spin angular momentum in level ground walking. 10.1177/0278364905058363 IS - 12 JF - The International Journal of Robotics Research EP - 1032 TI - Ground Reference Points in Legged Locomotion: Definitions, Biological Trajectories and Control Implications VL - 24 T2 - The International Journal of Robotics Research SP - 1013 AU - Popovic, Marko AU - Goswami, Ambarish AU - Herr, Hugh PY - 2005/12/01/ UR - http://dx.doi.org/10.1177/0278364905058363 ER -