title: Estimation of ground reaction force and zero moment point on a powered ankle-foot prosthesis.
abstract: The ground reaction force (GRF) and the zero moment point (ZMP) are important parameters for the advancement of biomimetic control of robotic lower-limb prosthetic devices. In this document a method to estimate GRF and ZMP on a motorized ankle-foot prosthesis (MIT Powered Ankle-Foot Prosthesis) is presented. The method proposed is based on the analysis of data collected from a sensory system embedded in the prosthetic device using a custom designed wearable computing unit. In order to evaluate the performance of the estimation methods described, standing and walking clinical studies were conducted on a transtibial amputee. The results were statistically compared to standard analysis methodologies employed in a gait laboratory. The average RMS error and correlation factor were calculated for all experimental sessions. By using a static analysis procedure, the estimation of the vertical component of GRF had an averaged correlation coefficient higher than 0.94. The estimated ZMP location had a distance error of less than 1 cm, equal to 4% of the anterior-posterior foot length or 12% of the medio-lateral foot width.
authors.affiliation: Massachusetts Institute of Technology, Biomechatronics., Media Laboratory, USA. ernesto@media.mit.edu
authors.forename: Ernesto C
authors.initials: EC
authors.lastname: Martinez-Villalpando
authors.forename: Hugh
authors.initials: H
authors.lastname: Herr
authors.forename: Matthew
authors.initials: M
authors.lastname: Farrell
mesh_terms: D000842:Ankle / Q000502:physiology*; D001186:Artificial Limbs; D005528:Foot / Q000502:physiology*; D006801:Humans; D011474:Prosthesis Design; D015203:Reproducibility of Results; D012371:Robotics; D013314:Stress, Mechanical