The strengths and weaknesses of inverted pendulum models of human walking

Abstract

-An investigation into the kinematic and kinetic predictions of two "inverted pendulum" (IP) models of gait was undertaken. The first model consisted of a single leg, with anthropometrically correct mass and moment of inertia, and a point mass at the hip representing the rest of the body. A second model incorporating the physiological extension of a head-arms-trunk (HAT) segment, held upright by an actuated hip moment, was developed for comparison. Simulations were performed, using both models, and quantitatively compared with empirical gait data. There was little difference between the two models' predictions of kinematics and ground reaction force (GRF). The models agreed well with empirical data through mid-stance (20-40% of the gait cycle) suggesting that IP models adequately simulate this phase (mean error less than one standard deviation). IP models are not cyclic, however, and cannot adequately simulate double support and stepto-step transition. This is because the forces under both legs augment each other during double support to increase the vertical GRF. The incorporation of an actuated hip joint was the most novel change and added a new dimension to the classic IP model. The hip moment curve produced was similar to those measured during experimental walking trials. As a result, it was interpreted that the primary role of the hip musculature in stance is to keep the HAT upright. Careful consideration of the differences between the models throws light on what the different terms within the GRF equation truly represent.

Study of Postural Adjustments for Humanoidal Helpmates

“…15, and also that they are similar to each other. This brings the conclusion that both pendulums are good representations of the human body, this observation is consistent with [16] which stated that both models have similar features. Fig.…”

“…In [16] it was demonstrated that the kinematics and ground reaction forces for single and double inverted pendulums are similar. In [20] the inverted pendulum models were used to represent the gait stance phase, an enhanced model was also proposed.…”

Reconfigurable Double Inverted Pendulum Applied to the Modelling of Human Robot Motion

“…In [20] comparison of two pendulum based models is presented: linear inverted pendulum (LIP) model and double inverted pendulum model. Linear inverted pendulum model is a standard model, in which the whole body is concentrated at one point mass, located at the top of the pendulum.…”

A Lagrange-based generalised formulation for the equations of motion of simple walking models

“…There are numerous examples of researchers using relatively simple dynamic models to 8 investigate the way in which human beings walk (Baker et al, 2004;Buczek et al, 2006;Kuo, 9 2007;McGrath et al, 2015b;Millard et al, 2011). Some have further expanded to models of 10 'moderate' complexity (Martin and Schmiedeler, 2014;McGrath et al, 2015a;Pandy and 11 Berme, 1988a, b).…”