Application of a gain scheduling control strategy to artificial stimulation of the quadriceps muscle

In the present paper, a gain scheduling approach is exploited to control the movement of the knee joint in paraplegic patients, who have recovered partial functionality of muscles through Functional Electrical Stimulation. In particular, first a NARX polynomial model is developed, by using data collected during a stimulation session on a patient; to this aim a new algorithm for structural identification is introduced. Then, the design of a standard LQ regulator is presented. Starting from the LQ control scheme a gain scheduling controller is derived so that the linearization property holds. Furthermore, a performance comparison between the presented gain scheduling controller and the LQ regulator is performed by means of simulations.