Control model of human stance using fuzzy logic |
| |
Authors: | Ron Jacobs |
| |
Institution: | (1) Institute of Biomedical Technology (BMTI), University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands, NL |
| |
Abstract: | A control model of human stance is proposed based on knowledge from behavioral experiments and physiological systems. The
proposed model is based on the control of global variables specific to body orientation and alignment, rather than on the
control of the body’s center of mass within the base of support. Furthermore, the proposed control model is not based on purely
inverted pendulum body mechanics where only motion at one joint is controlled, as for instance the ankle. In the proposed
model, the degrees of freedom are controlled by using reciprocal and synergistic muscle actions at multiple joints. The control
model is based on three sets of different global variables which act in parallel: (1) limb length and its derivative, (2) limb
orientation and its derivative, and (3) trunk attitude and its derivative. An important feature of the control model is the
use of fuzzy logic, which enables us to model experimental findings and physiological knowledge in a meaningful and explicit
way using fuzzy if-then rules. In the control model, 36 fuzzy if-then rules are implemented and applied using a four-linked segment model consisting of a trunk, thigh, shank and foot. Uni- and
biarticular limb muscles and trunk muscles are represented as torque actuators at each individual joint. In the model, three
sets of global variables act in parallel and make corrective and coordinated responses to internal, self-induced perturbations.
The data show that the use of global variables and fuzzy logic successfully enables us to model human standing with sway about
a point of equilibrium. Small changes in, for example, total body sway are comparable to those seen during natural sway in
human stance. The selected controllers—limb length, limb orientation and trunk attitude—seem to be appropriate for human stance
control.
Received: 30 October 1996/Accepted in revised form: 7 April 1997 |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|