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Iterative learning control for FES of the ankle


R. Nguyen, S. Micera, M. Morari

International Functional Electrical Stimulation Society Conference, Vienna, Austria

Existing methods for the control of the ankle joint during gait training are limited by poor performance or extensive tuning or training. Iterative learning control (ILC) has been effective in the control of functional electrical stimulation (FES) during repetitive tasks of the upper limbs. In this study, ILC was used to control the ankle joint via surface electrodes that stimulated the tibialis anterior and triceps surae muscles. The control objective was to track a repeating reference trajectory of the ankle obtained from normal walking. The controller was tested with 11 unimpaired individuals who were seated on a table with feet hanging over the edge. During a first experiment, individuals were asked to relax their legs and cease volitional effort. The controller provided good reference tracking and the root mean square error converged monotonically within 10 strides to approximately 2.5. During a second experiment, in addition to FES, individuals were asked to actively participate with voluntary activity to track the reference trajectory. The controller reduced FES assistance in the presence of the new voluntary activity. Good performance was achieved using the proposed controller, which will be used with the robotic gait trainer Lokomat to provide better gait training.


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% Autogenerated BibTeX entry
@InProceedings { NguMic:2010:IFA_3649,
    author={R. Nguyen and S. Micera and M. Morari},
    title={{Iterative learning control for FES of the ankle}},
    booktitle={International Functional Electrical Stimulation Society
    address={Vienna, Austria},
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