Detailed Study of Amplitude Nonlinearity in Piezoresistive Force Sensors

Leonel Paredes-Madrid,Elena Garcia,Luis Emmi,Pablo Gonzalez De Santos

doi:10.3390/s110908836

Leonel Paredes-Madrid, Elena Garcia + Show 2 more

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https://doi.org/10.3390/s110908836

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Abstract

This article upgrades the RC linear model presented for piezoresistive force sensors. Amplitude nonlinearity is found in sensor conductance, and a characteristic equation is formulated for modeling its response under DC-driving voltages below 1 V. The feasibility of such equation is tested on four FlexiForce model A201-100 piezoresistive sensors by varying the sourcing voltage and the applied forces. Since the characteristic equation proves to be valid, a method is presented for obtaining a specific sensitivity in sensor response by calculating the appropriate sourcing voltage and feedback resistor in the driving circuit; this provides plug-and-play capabilities to the device and reduces the start-up time of new applications where piezoresistive devices are to be used. Finally, a method for bypassing the amplitude nonlinearity is presented with the aim of reading sensor capacitance.

Highlights

Piezoresistive force sensors have demonstrated to be a good solution for applications demanding non-invasive force readings [1,2,3,4,5,6]
Because of the relative bulk and weight of load cells as compared to piezoresistive sensors, when a new robot or force-control system is under design, load-cell bulk and weight must be taken into account from the early stages of design
(15) can effectively model sensor behavior, because through our various optimization processes we have effectively reduced the estimation error of b by discarding the highly noisy data obtained under forces lower than 40 N

Summary

Introduction

Piezoresistive force sensors have demonstrated to be a good solution for applications demanding non-invasive force readings [1,2,3,4,5,6]. Load cells have demonstrated to be reliable force-measurement devices in many different systems [10,11] demanding high reliability and accuracy [12], e.g., force-control applications [13] and impact measurements [14]. In certain research fields, such as biomechanics, biomedical engineering and haptics, it is necessary to perform non-invasive force readings. Such readings cannot be carried out using bulky load cells

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