Time-varying identification of the neuromuscular system. I. Human joint dynamics

A time-varying system identification technique has been developed to track abrupt changes in system characteristics using ensemble input and output records. No a priori assumptions are required regarding the system structure, form of the nonstationary, or input characteristics. A simulation study has shown the method to be capable of tracking the time course of changes in human ankle-joint dynamics associated with an abrupt change in the level of voluntary activation. The method has proved to be robust in the presence of noise