People who use prosthetic arms usually only depend on visual feedback when positioning the arm, which can make activities for daily living challenging. With that in mind, a team of researchers designed a myoelectric arm prosthesis with wrist position feedback and conducted two tests to study the effect of position feedback on prosthetic control. The found that wrist position feedback reduced errors and improved success when participants moved the prosthesis to targeted positions.
A vibrotactile perception range test analyzed the participants’ sensitivity to the vibration and defined the optimal perception range used in the sensory feedback test. The sensory feedback test analyzed the effectiveness of the position feedback by comparing three feedback methods: of visual feedback (Vis-FB), wrist position feedback (WP-FB), and a combination of Vis-FB and WP-FB (VP-FB).
Six able-bodied subjects, four men and two women (28 ± 4 years), performed 20 movement combinations of five target positions. The WP-FB was transiently activated with five vibrating motors embedded in an armband to stimulate the residual limb when the prosthetic wrist rotated to the target positions. The experimental results showed that when WP-FB was added to the prosthetic control, the absolute angular error of the prosthetic wrist declined from 4.50 degrees to 1.08 degrees while the success rate increased from 0.34 to 0.84.
The open-access study, “Toward improving control performance of myoelectric arm prosthesis by adding wrist position feedback,” was published in Frontiers in Human Neuroscience.