Occupational biomechanics models deal with the evaluation of physical activ
ities such as lifting of loads. This allows the user to determine the stres
ses imposed on the musculoskeletal system while holding or moving a load. T
hese models are useful tools in estimating these stresses especially those
imposed on the lumbar spine. dynamic biomechanical models, as opposed to st
atic models require the displacement-time information to obtain the kinemat
ics needed to estimate the kinetics of the motion. However, the collection
of this displacement data is both tedious and can require expensive equipme
nt.
Simulation models on the other hand can provide an indirect means of perfor
ming the biomechanical analyses without having to collect the displacement-
time data. A typical simulation model for 2-D lifting activities will be pr
esented. The basis for this is the hypothesis that the body will perform th
e activity in such a manner so as to minimize the work done. Using this ass
umption an objective function was developed Subject to a set of constraints
. These constraints relate to the human movement, the physical workplace la
yout, and maintenance of balance. Using this model, it was possible to gene
rate the lifting motion patterns, as well as the kinematics and kinetics of
motion. The paper discusses the model development, the model output and th
e kinematics and kinetics of the simulation of the lifting action. (C) 1998
Published by Elsevier Science Ltd. All rights reserved.