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Title: Energy Shaping Control with Virtual Spring and Damper for Powered Exoskeletons
Task-invariant feedback control laws for powered exoskeletons are preferred to assist human users across varying locomotor activities. This goal can be achieved with energy shaping methods, where certain nonlinear partial differential equations, i.e., matching conditions, must be satisfied to find the achievable dynamics. Based on the energy shaping methods, open-loop systems can be mapped to closed-loop systems with a desired analytical expression of energy. In this paper, the desired energy consists of modified potential energy that is well-defined and unified across different contact conditions along with the energy of virtual springs and dampers that improve energy recycling during walking. The human-exoskeleton system achieves the input-output passivity and Lyapunov stability during the whole walking period with the proposed method. The corresponding controller provides assistive torques that closely match the human torques of a simulated biped model and able-bodied human subjects’ data.
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Award ID(s):
1949869 1652514
Publication Date:
Journal Name:
IEEE Conference on Decision and Control
Page Range or eLocation-ID:
3039 to 3045
Sponsoring Org:
National Science Foundation
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