Abstract:
Arm rotation is very useful for unilateral amputees and essential for bilateral amputees to
perform tasks of daily living. We propose a new approach for improving the control of prosthetic
arm rotation in amputees. This new approach involves inserting a small permanent magnet into
the distal end of the residual bone of subjects with upper limb amputations. When a subject
rotates the residual arm, the magnet will rotate with the residual bone, causing a change in
magnetic field distribution. This field change can be detected by magnetic sensors in the
prosthetic socket, from which information on the residual bone rotation is derived and used as an
input signal to control a powered prosthetic rotator. Proprioception remains intact for residual
limb skeletal structures, thus this control approach should be natural and easy to use. Studies
have been conducted in both simulation and physical experimental models to assess the
feasibility and performance of sensing the voluntary rotation of the residual bone with an
implanted magnet. The results from the studies are encouraging, suggesting potential clinical
applications to improve the control of powered prostheses with preservation of physiological
proprioceptive feedback.
