Cosimulation of Linear Feedback Postural Sway Model to Explore the Effects of Parkinson’s Disease

Abstract

The focus of this study was to design and develop a postural sway model using cosimulation of ADAMS dynamic modelling software and Simulink as the control system. This model could then be used to study the biomechanics and neuromuscular control of the system through physiological input parameters (controller gains, neuromuscular noise, and feedback time delay) and center of pressure (COP) output parameters. In the first study, we showed the characteristics of the model input parameters and their effect on the model robustness and COP output measures. Finally, we were able to develop a set of input model parameters that validated the model COP measures with experimental COP measures observed in healthy control (HC) subjects during eyes closed stance. In the second study, the validated HC parameters were used as a baseline for investigation of the effects of the changes of the input model parameters on the model COP measures when related to the experimental COP measures of a HC group and Parkinson’s disease (PD) group. This study showed that when the feedback time delay and proportional gain were independently studied and manipulated from the HC base set, no changes in the model COP measures could be related exclusively to either group. When investigating the neuromuscular noise and derivative gain parameters, varying these parameters caused changes in output COP measures that specifically related to PD and HC groups. This study has shown the possibility of reverse engineering biomechanics measures back to the control system. This allows for more complex models to be investigated and further studies to be carried out on subjects with injury, who are aging, or possess a neurological disease.