چكيده به لاتين
The walking is always an important goal in applications of functional electrical stimulation for spinal cord injury patients. Tracking desired trajectory in presence of uncertainties such as highly nonlinear, time-varying properties of electrically stimulated muscle, muscle fatigue, spasticity and external disturbances is a major challenge for restoring locomotion. In this thesis, a robust control strategy for generating walking in animal modelis presented using intramuscular stimulation. A high-order sliding mode (HOSM) is used for tracking control. The experiments were conducted on anesthetized cats. The intramuscular stimulation electrodes were inserted in the flexor and extensor muscles of the hip, knee and ankle joints.
Muscle fatigue is one of the most important limitation for producing functional movements. In this study, a methodwas introduced for reducing muscle fatigue and controlperormance was investigated; for example different types of modulation (pulse amplitude modulation (PAM) and pulse width modulation (PWM)) and also two types of stimulation (multimuscle and single muscle) were compared. The experiment results showed that tracking control error with PAM is lower than that with PWM. There is no significant difference (p=0.54) in muscle fatigue between PAM and PWM. The results also showedthat the tracking accuracy increased and muscle fatigue reduced usingMultimuscle stimulation. The results demonste that PAM provides better tracking control compared to the PWM. Using PAM technique, the means of tracking error are 4.2˚± 0.6˚ (11.2%), 2.5˚± 0.4˚ (13.3%), and 3.1˚± 0.3˚ (16.5%) for the ankle, knee, and hip joints of the right leg, respectively; and 3.9˚± 0.6˚ (10.6%), 2.5˚± 0.3˚ (13.3%), and 3.1˚± 0.3˚ (16.4%) for the ankle, knee and hip joints of the left leg, respectively.
