Physiological musculoskeletal model identification for the lower limbs control of paraplegic under implanted FES

This paper concerns the whole physiological parameters identification of a musculoskeletal model of a human subject. The patient is equipped with an implanted Functional Electrical Stimulation (FES) system as part of the SUAW´s European project. The biomechanical model represents the knee and its associated muscles. The identification protocol is noninvasive and based on the in-vivo experimental data acquisition of a Spinal Cord Injured (SCI) patient. However, the human noninvasive identification poses problems of inaccessibility to some data. The identification procedure consists of several steps, in order to identify: the anthropometrical parameters, the geometrical parameters, the joint mechanical parameters, the force-length relationship and the recruitment function. Up to now, only the quadriceps muscle is considered with the knee joint in the identification procedure. A cross-validation has been done using data set not used during the identification process. The identified model shows a satisfactory response comparing to the measured knee response, which is obtained by stimulating the quadriceps through the implanted FES system. In this work, knee model-parameters of the implanted subject were identified successfully using the noninvasive identification procedure.