Developing a Platform to Compare Effects of Somatotopic Accuracy of Feedback on Upper-Limb Myoelectric Performance

• Author / Creator

  Wells, Eric

• Despite advancements in myoelectric prostheses, a high percentage of prosthesis users continue to abandon their devices. A commonly cited reason for abandonment is lack of grip force sensory feedback. Researchers have attempted to restore grip force sensory feedback by stimulating the residual limb's skin surface in response to the prosthesis hand's measured grip force. Many techniques for stimulating the residual limb have been explored, such as electrotactile, vibrotactile, and mechanotactile feedback. Different experimenters use different stimulation sites, such as the forearm, upper-arm, or the finger of non-disabled participants. Promising results indicating improved prosthesis performance have been observed using these methods. However, each experiment typically has a unique apparatus with a different feedback stimulation location, making comparisons between studies difficult. The impact of the feedback location on myoelectric prosthesis performance has not been investigated. This thesis focused on developing a platform and experimental protocol to analyze the effects of feedback simulation location on prosthesis performance.
  Simulated prostheses are used to study myoelectric control with non-disabled participants while ensuring consistency between participants. In this work, a modular simulated prosthesis with location adjustable mechanotactile feedback devices was developed. The design was focused on comfort, weight reduction, and modularity. Low-cost pressure sensors were encapsulated in a compliant material and fit in the fingertips of the device. These compliant fingertips allowed for a substantial reduction in error for all non-standard loading conditions typical to prosthesis use. The simulated prosthesis will help researchers study feedback and control techniques in myoelectric prostheses by providing a reliable test apparatus that easily allows for manipulating various parameters.
  An experimental protocol was developed for comparing the performance differences of mechanotactile feedback delivered to the forearm or the fingertip. This protocol was validated through a pilot study of three participants. All participants showed similar difference values in the comparison between the finger
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  feedback condition and the arm feedback condition, creating large between-participant effect sizes for all outcome measures. These preliminary results indicate that the feedback location could play a factor in myoelectric prosthesis performance. A power analysis revealed that an estimated participant pool of n=8 would be required to achieve significance for comparing the arm and finger feedback conditions for all proposed metrics. Data analysis techniques were developed that will scale to a more extensive study. Recommendations were made on experimental apparatus improvements and protocol adjustments to reduce potential error sources for future experiments.

• Subjects / Keywords

  • Prosthetic
  • prosthesis
  • feedback
  • sensor
  • fingertip sensor
  • somatotopic
  • upper-limb

• Graduation date

  Spring 2021

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-h59b-p194

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.