A three-dimensional, two-part model of the foot, for use in a simulati
on of human gait, is presented. Previous simulations of gait have not
included the foot segment (e.g. Siegler et al., 1982, J. Biomechanics
15, 415-425) or have fastened it to the ground (e.g. Onyshko and Winte
r, 1980, J. Biomechanics 13, 361-368). A foot model based on viscoelas
tic elements (e.g. Meglan, 1991, Ph. D. thesis, Ohio State Univ.), all
ows more freedom of movement and thus models the physical system more
closely. The current model was developed by running simulations of the
foot in isolation from just before heel contact to just after toe-off
. The driving inputs to the simulation were the resultant ankle joint
forces and moments taken from a gait analysis. Nine linear, vertically
oriented spring/damper systems, positioned along the midline of the f
oot were used to model the combined viscoelastic behaviour of the foot
, shoe and door. Associated with each vertical spring/damper system we
re two orthogonally placed, linear, horizontal dampers used to provide
the shear components of the ground reaction force. Torques at the met
atarsal-phalangeal joint were supplied by a linear, torsional spring a
nd damper. Control about the vertical axis and the long axis of the fo
ot was achieved by the use of linear, torsional dampers. The predicted
kinetic and kinematic values are very similar to those taken from the
gait analysis. The model represents an improvement over previous work
because the transition from swing to stance was smooth and continuous
without the foot being constrained to any specific trajectory. (C) 19
96 Elsevier Science Ltd.