A 2-D simulation model for lifting activities

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.