Combined feedforward and feedback control of a redundant, nonlinear, dynamic musculoskeletal system

D. Blana, R. F. Kirsch, E. K. Chadwick

    Research output: Contribution to journalArticlepeer-review

    79 Citations (SciVal)

    Abstract

    A functional electrical stimulation controller is presented that uses a combination of feedforward and feedback for arm control in high-level injury. The feedforward controller generates the muscle activations nominally required for desired movements, and the feedback controller corrects for errors caused by muscle fatigue and external disturbances. The feedforward controller is an artificial neural network (ANN) which approximates the inverse dynamics of the arm. The feedback loop includes a PID controller in series with a second ANN representing the nonlinear properties and biomechanical interactions of muscles and joints. The controller was designed and tested using a two-joint musculoskeletal model of the arm that includes four mono-articular and two bi-articular muscles. Its performance during goal-oriented movements of varying amplitudes and durations showed a tracking error of less than 4 degrees in ideal conditions, and less than 10 degrees even in the case of considerable fatigue and external disturbances.
    Original languageEnglish
    Pages (from-to)533-542
    Number of pages10
    JournalMedical and Biological Engineering and Computing
    Volume47
    Issue number5
    Publication statusPublished - 01 May 2009

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