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Research/Prosthetics

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Overview

Naturally, upper-limb prosthesis users would like to interact with their surroundings with the same level of ease as able-bodied humans. Many researchers are working to make this become a reality, with the goal of creating an upper-limb prosthesis that deciphers the user’s cognitive motor commands, moves accordingly, and provides sensory feedback directly to the brain. One of the major challenges faced in this research is determining which sensations one should receive and how to provide the sensory information. Providing direct neural feedback is still not possible, but research continues in this area, while alternative feedback methods are also being explored.

Prosthesis signal flow. The user of a typical powered prosthesis knows his or her efferent commands, feels socket forces and torques, and can see the prosthesis when it is visible; however, the user cannot feel the limb’s movement because conventional prostheses do not provide proprioceptive motion feedback.
Prosthesis signal flow. The user of a typical powered prosthesis knows his or her efferent commands, feels socket forces and torques, and can see the prosthesis when it is visible; however, the user cannot feel the limb’s movement because conventional prostheses do not provide proprioceptive motion feedback.

This project has two main thrusts. First, we are investigating the importance of artificial proprioception in prosthesis control, especially as compared with vision. Proprioception is the knowledge of the positions and velocities of one’s limbs in space. We are conducting human subject studies to quantify the benefits of proprioception during simple tasks such as motion control and stiffness discrimination. The results of this research motivate the need to display artificial proprioception to the user of an upper-limb prosthesis. Second, we are developing methods of providing sensory feedback to an individual using a prosthetic limb. One such project explores the possibility of providing sensory feedback via vibrations on the sole of the foot. Another project investigates the possibility of providing proprioceptive feedback to an upper-limb prosthesis user via sensory substitution, the exact sensory feedback method and location still to be defined.

System for providing proprioceptive feedback to the right index finger in a one-degree-of-freedom motion control task. The user controls a virtual prosthetic finger in the task of grasping a virtual object by squeezing the finger and thumb together. The force sensor reading at the thumb controls the movement of a virtual finger on the computer screen. To provide proprioceptive feedback, the motor moves the user's real finger to match the movement of the virtual finger. To remove proprioceptive feedback, the motor holds the finger still.
System for providing proprioceptive feedback to the right index finger in a one-degree-of-freedom motion control task. The user controls a virtual prosthetic finger in the task of grasping a virtual object by squeezing the finger and thumb together. The force sensor reading at the thumb controls the movement of a virtual finger on the computer screen. To provide proprioceptive feedback, the motor moves the user's real finger to match the movement of the virtual finger. To remove proprioceptive feedback, the motor holds the finger still.
Sensory feedback via vibrations to the foot. Signals from the accelerometer are amplified and sent to the vibrating tactor packaged inside the insole. The waveform is also acquired through a data acquisition card for real-time visualization and frequency analysis.
Sensory feedback via vibrations to the foot. Signals from the accelerometer are amplified and sent to the vibrating tactor packaged inside the insole. The waveform is also acquired through a data acquisition card for real-time visualization and frequency analysis.

Future work will include developing a model of how the human body integrates proprioceptive and visual feedback to predict performance during simple tasks, creating the aforementioned sensory substitution system to display proprioceptive information to a prosthesis user, and testing the validity of our developed model using the designed sensory substitution system.

We collaborate with the Johns Hopkins Applied Physics Lab on the DARPA Revolutionizing Prosthetics 2009 project.

People

Publications

Conference Publications

  1. A. Blank, A. M. Okamura, and K. J. Kuchenbecker, "Effects of Proprioceptive Motion Feedback on Sighted and Non-Sighted Control of a Virtual Hand Prosthesis", 16th Symposium on Haptic Interfaces for Virtual Environments and Teleoperator Systems, 2008. In press.
  2. K. J. Kuchenbecker, N. Gurari, and A. M. Okamura, "Effects of Visual and Proprioceptive Motion Feedback on Human Control of Targeted Motion", 10th International Conference on Rehabiliation Robotics, 2007. (pdf)
  3. K. J. Kuchenbecker, N. Gurari, and A. M. Okamura, "Quantifying the Value of Visual and Haptic Position Feedback During Force-Based Motion Control", Second Joint Eurohaptics Conference and Symposium on Haptic Interfaces for Virtual Environments and Teleoperator Systems, 2007. (pdf)

Support

This work is supported by the Johns Hopkins University, NSF Graduate Research Fellowships, and DARPA Grant N66001-06-C-8005.

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This page was last modified 14:28, 4 August 2008.