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Rotation Control of a Prosthetic Hand Using Proprioceptive Feedback

Current solutions to help provide limb function to individuals with upper limb amputations include the basic hook prosthetic and complex reinnervation, in which residual nerves in the forearm are connected to chest muscles of a patient in order to control a prosthetic. Unfortunately, the hook prosthetic has limited real-world functionality, and while complex reinnervation gives the user a prostheses with functionality, in order to use this device the user must undergo significant rehabilitation and a highly invasive surgery. To overcome some of these limitations our team has developed forearm proprioceptive prosthetic device. Proprioception is the ability to control a device by the person’s perception of body position and orientation. Our design is ideal since the musculoskeletal system of the forearm remains largely intact following amputation. This allows for the device to be controlled by the user’s normal physiological rotation of their residual ulna and radius. Our device requires the implantation of a high density, strong field magnet on the radial bone. The implanted magnet interacts with an array of sensors embedded on the inside of a prosthetic socket. When a user rotates his/her forearm, the direction of this magnetic field will change based upon the position of the radial bone. The sensors embedded in the prosthetic are able to determine the angle of change and control a motor in the prosthetic wrist to move at the same rate and degree of twisting inferred from the user.