Evaluation of Pressure Capacitive Sensors for Application in Grasping and Manipulation Analysis.

Paola Pessia,Emiliano Schena,Francesca Cordella,Angelo Davalli,Loredana Zollo,Rinaldo Sacchetti

doi:10.3390/s17122846

Abstract

The analysis of the human grasping and manipulation capabilities is paramount for investigating human sensory-motor control and developing prosthetic and robotic hands resembling the human ones. A viable solution to perform this analysis is to develop instrumented objects measuring the interaction forces with the hand. In this context, the performance of the sensors embedded in the objects is crucial. This paper focuses on the experimental characterization of a class of capacitive pressure sensors suitable for biomechanical analysis. The analysis was performed in three loading conditions (Distributed load, 9 Tips load, and Wave-shaped load, thanks to three different inter-elements) via a traction/compression testing machine. Sensor assessment was also carried out under human- like grasping condition by placing a silicon material with the same properties of prosthetic cosmetic gloves in between the sensor and the inter-element in order to simulate the human skin. Data show that the input–output relationship of the analyzed, sensor is strongly influenced by both the loading condition (i.e., type of inter-element) and the grasping condition (with or without the silicon material). This needs to be taken into account to avoid significant measurement error. To go over this hurdle, the sensors have to be calibrated under each specific condition in order to apply suitable corrections to the sensor output and significantly improve the measurement accuracy.

Highlights

The human hand is the main interfacing tool between human beings and environment; it enables exploration of the world and learning thanks to perception
The distribution of the forces applied on object surfaces during grasping and manipulation is of paramount importance for studying the quality of a grasp performed by human, robotic or prosthetic hands [1,2,3]
Force and pressure data in grasping tasks are usually collected through two main approaches. The former is grounded on wearable solutions, e.g., sensors integrated in gloves [4,5] or directly positioned on the hand [6]; the latter resorts to the use of instrumented objects [7], e.g., common objects of daily life instrumented with tactile or force sensors

Summary

Introduction

The human hand is the main interfacing tool between human beings and environment; it enables exploration of the world and learning thanks to perception. Human grasping and manipulation capabilities, as well as discrimination of object physical properties and tactile scanning of a surface are essential for the execution of activities of daily living (ADLs). Force and pressure data in grasping tasks are usually collected through two main approaches. The former is grounded on wearable solutions, e.g., sensors integrated in gloves [4,5] or directly positioned on the hand [6]; the latter resorts to the use of instrumented objects [7], e.g., common objects of daily life instrumented with tactile or force sensors.

Methods

Findings

Discussion

Conclusion