A Novel Input Device for Robotic Prosthetic Hand: Design and Preliminary Results

Abstract

In this paper, we propose a novel input device for a robotic prosthetic hand based on capacitance change. The proposed device can sense the deformation of the skin due to the activity of the muscle by measuring the capacitance change between the skin and the electrode. Therefore, it can be used as a sensor for estimating a user's intention through medical electrodiagnostic techniques such as electromyogram (EMG)and force myography (FMG). The proposed device can acquire data in a non-invasive way and is advantageous with easier data processing than that for an EMG signal. Moreover, it is resistant to the impedance change of skin because the capacitance is measured in a non-contact manner, unlike the existing methods which work with direct contact with the skin such as EMG. Additionally, unlike FMG, the device is lightly attached to the skin without being strongly fixed with velcro, which offsets problems that occur while re-wearing the device. To demonstrate the feasibility of the proposed idea, three of the newly developed input devices were used to classify four hand movements (fist, scissors, paper, and rest)using a multilayer perceptron (MLP). As a result, the classification success rates for the fist, paper, scissor, and rest motions were obtained as 99.3%, 98.3%, 98.4%, and 99.1%, respectively.