Journal article Open Access

A patient-controlled functional electrical stimulation system for arm weight relief

Klauer, Christian; Ferrante, Simona; Ambrosini, Emilia; Shiri, U; Dähne, F; Schmehl, I; Pedrocchi, Alessandra; Schauer, Thomas


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{
  "DOI": "10.1016/j.medengphy.2016.06.006", 
  "language": "eng", 
  "title": "A patient-controlled functional electrical stimulation system for arm weight relief", 
  "issued": {
    "date-parts": [
      [
        2017, 
        11, 
        1
      ]
    ]
  }, 
  "abstract": "<p>A patient-driven control strategy for Functional Electrical Stimulation (FES), which amplifies volitionally-initiated shoulder abductions, is proposed to improve stroke patients&#39; rehabilitation. Based on the measured abduction angle, a FES-induced muscle recruitment is generated that yields a pre-specified percentage of this angle - yielding arm weight relief. To guarantee the correct recruitment also under fatigue and uncertain muscle activation we employ feedback control of the recruitment level determined by filtering the FES-evoked electromyogram. Filter parameters are user-optimized to obtain a linear relation between filter output and angle with a good signal-to-noise ratio. The auto-tuned recruitment controller (RC) was tested on five healthy subjects and compared to direct stimulation (DS) while muscle fatigue progressively occurred. Results showed a more linear relation between recruitment level and angle than between non-controlled stimulation intensity and angle (R<sup>2</sup>=0.93 vs. R<sup>2</sup>=0.79, angular range of 54&deg;). After 6&nbsp;min of stimulation, abduction decreased by 42% &plusmn; 14 for DS and by 0% &plusmn; 12 for RC, showing an effective compensation of fatigue. RC yielded significant smaller errors than DS in generating desired angles (0.23% &plusmn; 5.9 vs. 14.6% &plusmn; 9.7). When FES-induced arm weight support was provided, a mean reduction of the volitional effort (determined by Electromyography) of 78% was achieved compared to angular tracking without FES. First experiments with one acute stroke patient are also reported.</p>", 
  "author": [
    {
      "family": "Klauer, Christian"
    }, 
    {
      "family": "Ferrante, Simona"
    }, 
    {
      "family": "Ambrosini, Emilia"
    }, 
    {
      "family": "Shiri, U"
    }, 
    {
      "family": "D\u00e4hne, F"
    }, 
    {
      "family": "Schmehl, I"
    }, 
    {
      "family": "Pedrocchi, Alessandra"
    }, 
    {
      "family": "Schauer, Thomas"
    }
  ], 
  "type": "article-journal", 
  "id": "1240916"
}
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