The Optimal Controller Delay for Myoelectric Prostheses

• Published in: IEEE transactions on neural systems and rehabilitation engineering Vol. 15; no. 1; pp. 111 - 118
• Main Authors: Farrell, Todd R., Weir, Richard F.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01-03-2007
• Subjects: Analysis of variance; Artificial Limbs; Box and Block Test; Degradation; delay; Delay effects; Electric Stimulation Therapy - methods; Electromyography; Equipment Failure Analysis; Feedback - physiology; Hand - physiopathology; Hand Strength - physiology; Humans; Muscle, Skeletal - innervation; Muscle, Skeletal - physiology; myo-pulse control; myoelectric; Optimal control; Performance analysis; Performance evaluation; prostheses; prosthesis; Prosthesis Design; Prosthetics; Signal analysis; Testing; Therapy, Computer-Assisted - methods
• ISSN: 1534-4320
• DOI: 10.1109/TNSRE.2007.891391

A tradeoff exists when considering the delay created by multifunctional prosthesis controllers. Large controller delays maximize the amount of time available for EMG signal collection and analysis (and thus maximize classification accuracy); however, large delays also degrade prosthesis performance by decreasing the responsiveness of the prosthesis. To elucidate an "optimal controller delay" twenty able-bodied subjects performed the Box and Block Test using a device called PHABS (prosthetic hand for able bodied subjects). Tests were conducted with seven different levels of controller delay ranging from nearly 0-300 ms and with two different artificial hand speeds. Based on repeted measures ANOVA analysis and a linear mixed effects model, the optimal controller delay was found to range between approximately 100 ms for fast prehensors and 125 ms for slower prehensors. Furthermore, the linear mixed effects model shows that there is a linear degradation in performance with increasing delay