Intention-Based EMG Control for Powered Exoskeletons

• Published in: IEEE transactions on biomedical engineering Vol. 59; no. 8; pp. 2180 - 2190
• Main Authors: Lenzi, Tommaso, De Rossi, Stefano Marco Maria, Vitiello, Nicola, Carrozza, Maria Chiara
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.08.2012; Institute of Electrical and Electronics Engineers
• Subjects: Adult; Algorithms; Assistive robotics; Biological and medical sciences; Biomechanical Phenomena - physiology; Computerized, statistical medical data processing and models in biomedicine; Elbow; Elbow - physiology; Electrodiagnosis. Electric activity recording; Electromyography; electromyography (EMG) control; Electromyography - instrumentation; Electromyography - methods; Exoskeletons; Female; Humans; Investigative techniques, diagnostic techniques (general aspects); Joints; Male; Medical management aid. Diagnosis aid; Medical sciences; Muscles; Nervous system; powered exoskeletons; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Robotics - instrumentation; Robots; Self-Help Devices; Signal Processing, Computer-Assisted; Technology. Biomaterials. Equipments. Material. Instrumentation; Torque; Electrodiagnosis; Assistive robotics; powered exoskeletons; Electrophysiology; Electromyography; Robotics; Biomedical engineering; electromyography (EMG) control
• ISSN: 0018-9294; 1558-2531; 1558-2531
• DOI: 10.1109/TBME.2012.2198821

Electromyographical (EMG) signals have been frequently used to estimate human muscular torques. In the field of human-assistive robotics, these methods provide valuable information to provide effectively support to the user. However, their usability is strongly limited by the necessity of complex user-dependent and session-dependent calibration procedures, which confine their use to the laboratory environment. Nonetheless, an accurate estimate of muscle torque could be unnecessary to provide effective movement assistance to users. The natural ability of human central nervous system of adapting to external disturbances could compensate for a lower accuracy of the torque provided by the robot and maintain the movement accuracy unaltered, while the effort is reduced. In order to explore this possibility, in this paper we study the reaction of ten healthy subjects to the assistance provided through a proportional EMG control applied by an elbow powered exoskeleton. This system gives only a rough estimate of the user muscular torque but does not require any specific calibration. Experimental results clearly show that subjects adapt almost instantaneously to the assistance provided by the robot and can reduce their effort while keeping full control of the movement under different dynamic conditions (i.e., no alterations of movement accuracy are observed).