Integrated Voluntary-Reactive Control of a Human-SuperLimb Hybrid System for Hemiplegic Patient Support

Abstract

This letter presents a new type of wearable robot, called the Hybrid SuperLimb, which integrates voluntary human movements and the autonomous reactive control of a robotic limb. Some degrees of freedom (DOF) of the SuperLimb are powered by human body movements and are controlled voluntarily and directly by the human, while other DOF are powered by robot actuators and are controlled automatically. A data-driven methodology for identifying the subspaces of voluntary and reactive control is developed for bimanual manipulation. It is applied to support hemiplegic patients' use of a knife and fork. The bimanual operation of a knife and fork demonstrated by a healthy subject is measured. Correlation data analysis reveals that a few DOF of the hand holding a knife are not significantly correlated with any other DOF, indicating independent, voluntary movements. Furthermore, a few DOF are strongly correlated with the fork movements and, thereby, predictable. The latter can be replaced by robot actuators controlled autonomously with a regression prediction. A prototype hybrid SuperLimb is designed and tested. The motion of a patient's foot is transmitted to activate the voluntary DOF, which is associated with cutting motion. Two robotic actuators are controlled using a principal component regression predicting the knife position in response to the fork movement.