Functional electrostimulator 8 channels with feedback loop using digital controllers

Abstract

A Microcontrolled Functional Electrical Stimulation (FES) system will be developed for generating movements in the lower limbs of paraplegics in order to improve their life expectancy and accelerate their rehabilitation process. The neuromuscular stimulator will consist of eight channels, microcontrolled, rectangular, biphasic current waveform, balanced load, with the ability to deliver current with amplitude of 120 mA using pulse width modulation (PWM). A PID controller will be implemented for using with the microcontrolled stimulator, and the energy to be applied to the stimulated member can be determined in order to keep the leg in a pre-determined position. The design of this controller will be based on a linear second order mathematical model, which represents the behavior of a muscle strength due to an electrical stimulus. For validation and testing the microcontrolled electrical stimulator system, mathematical functions that represent the physiological behavior of the lower limbs will be transformed into electronic circuits. Thus, this project will integrate the controller, the stimulator and the muscle model, observing the time response during electrical stimulation, avoiding testing it with patients and preserving the physical integrity of the volunteers. (AU)