3D-Printed All-Dielectric Electromagnetic Encoders with Synchronous Reading for Measuring Displacements and Velocities.

Cristian Herrojo,Ferran Paredes,Ferran Martín

doi:10.3390/s20174837

Cristian Herrojo, Ferran Paredes + Show 1 more

Open Access

https://doi.org/10.3390/s20174837

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Abstract

In this paper, 3D-printed electromagnetic (or microwave) encoders with synchronous reading based on permittivity contrast, and devoted to the measurement of displacements and velocities, are reported for the first time. The considered encoders are based on two chains of linearly shaped apertures made on a 3D-printed high-permittivity dielectric material. One such aperture chain contains the identification (ID) code, whereas the other chain provides the clock signal. Synchronous reading is necessary in order to determine the absolute position if the velocity between the encoder and the sensitive part of the reader is not constant. Such absolute position can be determined as long as the whole encoder is encoded with the so-called de Bruijn sequence. For encoder reading, a splitter/combiner structure with each branch loaded with a series gap and a slot resonator (each one tuned to a different frequency) is considered. Such a structure is able to detect the presence of the apertures when the encoder is displaced, at short distance, over the slots. Thus, by injecting two harmonic signals, conveniently tuned, at the input port of the splitter/combiner structure, two amplitude modulated (AM) signals are generated by tag motion at the output port of the sensitive part of the reader. One of the AM envelope functions provides the absolute position, whereas the other one provides the clock signal and the velocity of the encoder. These synchronous 3D-printed all-dielectric encoders based on permittivity contrast are a good alternative to microwave encoders based on metallic inclusions in those applications where low cost as well as major robustness against mechanical wearing and aging effects are the main concerns.

Highlights

Optical encoders are widely used in many applications such as the automotive industry, elevators, robotics, and conveyor belts, among others, in order to accurately measure linear or angular displacements and velocities [1,2,3]
All-dielectric 3D-printed electromagnetic encoders based on permittivity contrast with
All-dielectric 3D-printed electromagnetic encoders based on permittivity contrast with synchronous reading, useful for measuring displacements and velocities, have been reported for the synchronous reading, useful for measuring displacements and velocities, have been reported for the first time

Summary

Introduction

Optical encoders are widely used in many applications such as the automotive industry, elevators, robotics, and conveyor belts, among others, in order to accurately measure linear or angular displacements and velocities [1,2,3]. In [11,12,13,14,15], microwave encoders based on a linear or angular chain of metallic inclusions implemented on a dielectric substrate were reported. The main drawback of this approach is the limited robustness against mechanical wearing (e.g., due to friction) and aging effects To alleviate this problem, all-dielectric microwave encoders based on permittivity contrast were reported in [16,17]. All-dielectric microwave encoders based on permittivity contrast were reported in [16,17] In such encoders, the metallic inclusions were replaced with apertures or dielectric inclusions made on the considered substrate, and the sensitive part of the reader was designed in order to detect the presence/absence of apertures (or dielectric inclusions).

Reader and Encoder Design

Circuit

Experimental Validation

Conclusions