Control of Prosthetic Hands via the Peripheral Nervous System

Abstract

This paper intends to provide a critical review of the literature on the technological issues on control and sensorization of hand prostheses interfacing with the Peripheral Nervous System (i.e., PNS), and their experimental validation on amputees. The study opens with an in-depth analysis of control solutions and sensorization features of research and commercially available prosthetic hands. Pros and cons of adopted technologies, signal processing techniques and motion control solutions are investigated. Special emphasis is then dedicated to the recent studies on the restoration of tactile perception in amputees through neural interfaces. The paper finally proposes a number of suggestions for designing the prosthetic system able to re-establish a bidirectional communication with the PNS and foster the prosthesis natural control.

Keywords: PNS-based prosthetic hand; grasping; manipulation; motion control; sensory feedback.

Figure 1

Block scheme of the PNS-based control of a prosthetic system. Readapted from and (Raspopovic et al., 2014).

Figure 2

Details of the tactile sensors (red circles) embedded in prosthetic hands. (A) Piezo-resistive sensor on fingertips of UTAH-MIT Hand (Courtesy of Compuer Histiry Museum) (B) Stain gauges based SUVA system integrated in the thumb of SensorHand Speed (C) Tactile sensor with piezo-electric, piezo-resistive and thermal sensing units mounted on Southampton Hand (Cotton et al., 2007); (D) Strain gauge placed on PIP joint of UB Hand III (Lotti et al., 2004); (E) Optical sensors on thumb and index of SmartHand (Cipriani et al., 2011); (F) MEMS tactile sensors on fingertips of IH2 Azzurra (Courtesy of Prensilia srl).

Figure 3

(A) Perceived localization of sensation after—median nerve tf-LIFE4 stimulation on left and after ulnar nerve tf-LIFE4 stimulation on right (Rossini et al., 2010); (B) Elicited hand areas in Raspopovic et al. (2014); (C) Tactile perception via neurostimulation (Ortiz-Catalan et al., 2014a). The dark points represent the electrode-specific projected field repeatedly reported (over 11 months) for a single pulse at stimulation threshold; (D) Sensation locations after threshold stimulation at week 3 post-op (Tan et al., 2014). The letter represents the nerve and the number represents the stimulus channel; (E) Pressure tactile perception on varying of impulse duration (Tan et al., 2014).

Figure 4

Location of the 20 FSR sensors in Kargov et al. (2004).