Fuzzy optimal control of sit-to-stand movement in a biomechanical model

Abstract

The Physiological studies illustrate that human sit-to-stand (STS) movement consists of different phases that are distinguishable by their kinematics constraints and stability requirements. We propose to use a fuzzy TSK biomechanical model to analyze, integrate, and study biomechanical STS movement. The fuzzy model combines two local linear models defined at the initiation and termination points of STS using Gaussian membership functions that operate on measurement of knee flexion. Further, we develop TSK fuzzy controllers that employ H₂ and H_∞ optimal control techniques for effective regulation of biomechanical STS. The fuzzy controllers similarly combine knowledge from local linear optimal controllers via membership functions. Our simulation results show that fuzzy TSK modeling is useful for the synthesis of STS movement because of its relevance with physiological principles and the use of localized control strategies for the joint torques.