Evaluation of a torque driven simulation model of tumbling

2010-06-09T09:08:04Z (GMT) by Fred Yeadon Mark King
The use of computer simulation models in studies of human movement is now widespread. Most of these models, however, have not been evaluated in a quantitative manner in order to establish the level of accuracy that may be expected. Without such an evaluation little credence should be given to the published results and conclusions. This paper presents a simulation model of tumbling takeoffs which is evaluated by comparing the simulation output with an actual performance of an elite gymnast. A five segment planar model was developed to simulate tumbling takeoffs. The model comprised rigid foot, leg, thigh, trunk + head and arm segments with two damped linear springs to represent the elasticity of the tumbling track / gymnast interface. Torque generators were included at the ankle, knee, hip and shoulder joints in order to allow each joint to open actively during the takeoff. The model was customised to the elite gymnast by determining subject specific inertia and torque parameters. Good agreement was found between actual and simulated tumbling performances of a double layout somersault with 1% difference in the linear and angular momenta at takeoff. Allowing the activation timings of the four torque generators to vary resulted in an optimised simulation which was some 0.32 m higher than the evaluation simulation. These simulations suggest that the model is a realistic representation of the elite gymnast since otherwise the model would either fail to reproduce the double layout somersault performance or would produce a very different optimised solution.