title: Redundancy resolution of the human arm and an upper limb exoskeleton.
abstract: The human arm has 7 degrees of freedom (DOF) while only 6 DOF are required to position the wrist and orient the palm. Thus, the inverse kinematics of an human arm has a nonunique solution. Resolving this redundancy becomes critical as the human interacts with a wearable robot and the inverse kinematics solution of these two coupled systems must be identical to guarantee an seamless integration. The redundancy of the arm can be formulated by defining the swivel angle, the rotation angle of the plane defined by the upper and lower arm around a virtual axis that connects the shoulder and wrist joints. Analyzing reaching tasks recorded with a motion capture system indicates that the swivel angle is selected such that when the elbow joint is flexed, the palm points to the head. Based on these experimental results, a new criterion is formed to resolve the human arm redundancy. This criterion was implemented into the control algorithm of an upper limb 7-DOF wearable robot. Experimental results indicate that by using the proposed redundancy resolution criterion, the error between the predicted and the actual swivel angle adopted by the motor control system is less then 5°.
authors.affiliation: Department of Electrical Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA. hyunchul78@gmail.com
authors.forename: Hyunchul
authors.initials: H
authors.lastname: Kim
authors.forename: Levi Makaio
authors.initials: LM
authors.lastname: Miller
authors.forename: Nancy
authors.initials: N
authors.lastname: Byl
authors.forename: Gary M
authors.initials: GM
authors.lastname: Abrams
authors.forename: Jacob
authors.initials: J
authors.lastname: Rosen
mesh_terms: D001132:Arm / Q000502:physiology*; D040761:Biomimetic Materials; D003198:Computer Simulation; D017076:Computer-Aided Design; D005246:Feedback; D006801:Humans; D007596:Joints / Q000502:physiology*; D008328:Man-Machine Systems; D008954:Models, Biological; D009989:Orthotic Devices; D011474:Prosthesis Design; D012371:Robotics / Q000295:instrumentation* / Q000379:methods*