Design and evaluation of prosthetic shoulder controller

1
Design and evaluation of prosthetic shoulder
controller

• Joseph E. Barton, PhD John D. Sorkin, MD, PhD

2

• Aim
• Develop 2-degree-of-freedom (DOF) shoulder
  position transducer to control sensing shoulder
  protraction-retraction and elevation-depression
  of powered prosthetic humerus.
• Develop evaluation protocol based on Fitts law
  to assess devices performance.
• Relevance
• Study supports development of powered prosthetic
  shoulder joints for people with shoulder
  disarticulation and very high-level transhumeral
  amputation.

3
Method

• Developed and tested
• 3 control assemblies designed to convert shoulder
  motion into control signals.
• Body socket designed worn on side of thorax that
  had experienced amputation.
• Socket sensed shoulder motion via
• Steel rods through proprioceptive and tactile
  feedback.
• Nylon rod through proprioceptive feedback.

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Results

• Transducers providing resistance to shoulder
  movement performed better than those providing no
  resistance.
• Position control scheme (effector velocity
  proportional to shoulder position) performed
  better than velocity control scheme.
• Transducer could control motion along any 2 DOFs.
• Transducer could be used in 4-DOF control scheme
  by sequentially controlling 2 DOFs at a time.

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Conclusion

• Evaluation protocol has general applicability for
  researchers and practitioners.
• Researchers compare different prosthesis designs
  and control schemes
• Practitioners evaluate and train people with
  amputation in prosthesis use.