Controle de ângulos de flexão de modelo de perna humana através de estimulação elétrica funcional em malha-fechada e coativação de músculos

Abstract

The application of functional electrical stimulation techniques (FES) consists of applying electrical pulses to nerves or muscles in order to obtain muscle contraction. These excitations cause limb movements, in general, upper and lower. This technique is used in the treatment of people with limited movements due to neurological diseases, accidents etc. However, given the non-linear nature of the muscles in the human body, a desired response cannot be guaranteed just by applying such impulses to the muscles. Therefore, it is necessary to study control techniques. In this work, control strategies were used in order to control the angles of knee flexion and hip flexion through the excitation of the muscles responsible for both movements. The identification and modeling techniques implemented include: study of the behavior of the system to step-type responses and application of pseudo-random binary signals to identify equations that model the behavior observed through numerical methods. Subsequently, the design of RST controllers was carried out through the allocation of auxiliary poles. The values of the bending angles are obtained through the integration of OpenSim and MATLAB software. First, the individual controls of each movement are carried out to understand the performance of their respective controllers independently. Muscle coactivation and flexion angle control were achieved through RST controllers and denoted the possibility of expanding and exploring different control techniques in this field of research. At the end, the boundaries of stabilization were explored for hip flexion beyond 40°, getting unstable values. Therefore, techniques of non-linear control were proposed.