The goal of this project is to create an intuitive control scheme for rotation of a prosthetic joint that preserves proprioception of limb rotation. Such a control scheme would reduce the cognitive burden of controlling the prosthetic limb and allow the incorporation of additional prosthesis movements, thus reducing the burden of disability. This project seeks to advance this goal by developing the technology of an osseo-magnetic link for prosthetic wrist rotation. Natural control of wrist rotation and preservation of proprioception will be achieved by implanting a permanent magnet into the distal end of the residual radius bone, and magnetic field sensors into the surrounding prosthetic socket. By sensing the change in magnetic field distribution as the subject rotates their residual forearm bones, the angle of rotation can be calculated and applied to the prosthetic wrist rotator. The intact proprioceptive pathways of the forearm will allow the user to intuitively know the rotation of the residual bone, and, as a result, the rotation of the prosthetic wrist. This proposed project is based on the following aims: 1) optimization of magnetic sensors, 2) optimization of sensing algorithm and 3) robustness testing. Specifically, during this phase we will research available magnetic sensor technologies and select a sensor that provides the best compromise between sensitivity, power consumption and package size. We will also investigate control algorithm refinements with the goal of developing a numerically stable and computationally simple approach. Lastly, we will investigate the effects of external electromagnetic field interference on prototype performance and develop a shielding approach if it is warranted.
Transradial (above wrist) amputation is a debilitating injury and results in severe disability. The goal of this research project is to develop a control technology for transradial prostheses using a magnetic link: a magnet will be placed in the residual arm bone so that a series of sensors can track its rotation and control a motorized wrist rotator. This will allow the user to naturally and intuitively control the rotation of their prosthetic wrist, thus increasing the functionality of the prosthesis and reducing the mental burden of use.
