Custom Force Sensor and Sensory Feedback System to Enable Grip Control of a Robotic Prosthetic Hand

Amputees living in the developing world can benefit greatly from a dexterous low-cost robotic prosthetic hand that can be controlled via electromyography (EMG). This research addresses part of the challenge of designing and constructing such a low-cost device. In particular, the development of novel and functionally suitable fingertip sensors is presented in this paper. The sensors allowed for the user with a trans-humeral amputation to intuitively control grip strength of the robotic prosthetic hand with the help of an EMG electrode placed on the bicep muscle, as well as, a haptic sensory feedback system. The fingertip sensors illustrated a stable linear relationship with force, an even sensitivity to force over the pulp of finger and the medial and lateral sides of the finger above the distal inter-phalangeal joint across the fingertip. Additionally, it had a low cost of construction ($1.00) and the ability to fit on curved surfaces. Two test subjects evaluated the performance of the sensors in combination with the haptic sensory feedback system. The use of the novel sensors allowed for the test subjects to discriminate the forces experienced by each finger when gripping objects of different shapes, with an accuracy of 80% and 73% accuracy respectively. Hence, the fingertip sensors along with haptic feedback can provide a possible solution for amputees to regain the sense a touch and at a low cost. This is a step towards a cost effective ($(\pm\$ 150)$, yet functional robotic prosthetic hand for amputees.