Switching curve controller for FES-assisted standing up and sitting down

Michael J. Dolan, Brian J. Andrews, Petrus H. Veltink

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    A low-level, closed-loop controller for FES-assisted standing up and sitting down is described. If, for able-bodied individuals, when standing up and sitting down, the knee angular velocity is plotted against knee angle, consistent phase-plane trajectories are produced. The bang-bang controller uses a model of this trajectory as a switching curve. The design rationale for the controller was the desire to avoid injuries that might occur if knee-locking on standing up and seat-contact on sitting down are not adequately controlled. This switching curve controller (SCC) was incorporated within a hierarchical, finite state control scheme, with electrical stimulation applied bilaterally to the knee extensors. The SCC was tested in a pilot study on a female volunteer with paraplegia (T5/6 ASIA A) and evaluated against an unramped, open-loop controller (OLC). The vertical hand forces and knee angles were measured. The subject was able to achieve standing up and sitting down safely using both controllers. For standing up, the SCC was not found to offer any quantifiable advantages over the OLC and was found to increase the hand force by 8.4%. In contrast, for sitting down the SCC was found to reduce the knee angular velocities as the subject approached the seat by 27%, demonstrating a safer, softer landing.
    Original languageUndefined
    Pages (from-to)167-171
    Number of pages5
    JournalIEEE transactions on rehabilitation engineering
    Issue number2
    Publication statusPublished - 1998


    • METIS-112289
    • IR-61419
    • FES-assisted standing up
    • hierarchical finite state control scheme
    • bang-bang controller
    • knee angle
    • knee angular velocity
    • knee extensors
    • knee-locking
    • consistent phase-plane trajectories
    • unramped open-loop controller
    • vertical hand forces
    • low-level closed-loop controller
    • injuries
    • switching curve controller
    • female volunteer with paraplegia
    • able-bodied individuals
    • safer softer landing
    • seat-contact
    • bilateral electrical stimulation
    • sitting down

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