گسترش يك سيستم تحريك كننده عصبي - عضلاني مدار - بسته كامپيوتر براي كنترل بي درنگ حركت در عضو فلج

Development of a Computer-based Closed-loop Neuromuscular Electrical Stimulation for Real-Time Movement Control of Paralyzed Limb

In this paper, a closed-loop multi-channel Functional Neuromuscular Electrical Stimulation (FNS) system is designed and implemented for real-time control of the paralyzed limb. The system is used to acquire feedback information and to supply stimulation patterns for on-line activation of paralyzed muscles. The system is capable to modulate the current amplitude and pulse width, simultaneously. This feature offers fine movement control. The key feature that have to be considered in the design of a closed-loop multi-channel neuromuscular electrical stimulation system is the reliability. The system needs to be easy to use and easy to implement any controller scheme. For implementing such a closed-loop FNS system, appropriate computer software is required. In our case, we used Matlab Simulink, Real-Time Workshop, and Real-Time Windows Target under Windows. The results of cyclic leg movement on a complete level T7 spinal cord injury paraplegic show that pulse width modulation produces more smooth movement than pulse amplitude modulation. For evaluating the capability of system for real-time control of the paralyzed limb, a PID controller is used. PIDʹs coefficients are adjusted based on Ziegler-Nichols method. The results show that the system can adjust the parameters of stimulation signals according to control strategy. It is found that the PID controller could not control the knee joint angle for whole range of motion. Muscle fatigue is one of major problems in functional neuromuscular stimulation. The results show that the closed-loop control can control the knee joint position during prolonged electrical stimulation.