Development and Integration of Tactors onto a Prosthetic Socket for Tactile Sensory Feedback in Upper Limb Amputees

• Author / Creator

  Evans, Katherine R.

• Myoelectric prostheses have recently undergone extensive developments in their complexity and movement patterns, yet controlling these devices can be difficult as they lack the sensory feedback provided by traditional body powered prostheses. With targeted sensory reinnervation surgery, sensory nerves are relocated within the residual limb so that when touched on part of the reinnervated skin, the patient feels as though they are being touched on their missing limb. This restored hand map can be harnessed to provide feedback to the patient such that when they grip something with a robotic hand, a small device (termed tactor) pushes into their reinnervated skin and they feel as if they are gripping the object directly. The aim of this thesis work was to refine the design of this tactor system, evaluate various methods of system measurement and control, and integrate the tactor system onto an above-elbow prosthetic limb. A review of existing sensory feedback devices was conducted, where modality matched mechanotactile feedback was found to be the most promising non-invasive method of providing feedback to the user. Two tactor designs were investigated; a linear tactor, and a cable-driven tactor with a reduced vertical profile. Tactor parameters were optimized and evaluated to improve functionality, minimize size, cost, and weight, as well as quantify system capabilities. Two cable-driven tactors were integrated onto an above-elbow prosthetic socket for initial system evaluation, a task that has yet to be demonstrated elsewhere. Recommendations from this evaluation led to further investigation into methods of system measurement and control, as well as a preliminary investigation of various sealing methods for tactor integration, where an optimal membrane seal was determined. This tactor system is significantly less expensive than research versions currently available, however there is a trade-off in closed-loop control performance, which yields less accuracy and responds outside of the 200 ms threshold of noticeable delay. There is a need for improved measurement and control, collection of usability data to provide guidance for further refinement of the design, as well as further study into the long term performance of the system. While future work is warranted, this thesis provides significant contributions to the body of knowledge surrounding the design and integration of tactor systems onto a prosthetic socket. These findings will aid in effective translation of these devices to a clinical setting, which has the potential to improve the quality of life for upper limb amputees.

• Subjects / Keywords

  • Upper limb
  • Sensory feedback
  • Tactor
  • Mechanotactile
  • Prosthesis
  • Integration

• Graduation date

  Spring 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3N87350N

• 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.