Impact of a Photodiode’s Angular Characteristics on RSS-Based VLP Accuracy

Sander Bastiaens,David Plets,Willem Raes,Nobby Stevens,Wout Joseph,Luc Martens

doi:10.1109/access.2020.2991298

Sander Bastiaens, David Plets + Show 4 more

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https://doi.org/10.1109/access.2020.2991298

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Abstract

Photodiode (PD)-based Visible Light Positioning (VLP)-based localisation systems seem propitious for the low-cost tracking and route-configurable navigation of automated guided vehicles, found in warehouse settings. Delivering the required high accuracy, currently necessitates measuring and fitting the received power - distance relation. This paper shows that accurately modelling the PD receiver & x2019;s angular characteristics obsoletes this calibrating fit, while still providing accurate positioning estimates. A new responsivity model Square (SQ) is proposed, which is a function of the square of the incidence angle rather than its cosine. Both its aptitude in matching real-life propagation and its associated localisation accuracy are verified using two extensive measurement sets, each detailing the propagation of a PD moving across a 2D plane 3 m below a 4-LED plane. SQ is compared to the responsivity and calibration fit models available in the literature. In conjunction with model-based fingerprinting positioning, SQ outscores the Lambertian and generalised Lambertian model in terms of the 90(th) percentile root-mean-square error (rMSE) $p_{90}$ by 45.36 cm (83.1 & x0025;) and 0.84 cm (8.4 & x0025;) respectively for the non-Lambertian-like receiver. $SQ$ exhibits an equivalent performance as the generalised Lambertian model for the Lambertian-like photodiode. Accounting for the appropriate receiver model can also boost trilateration & x2019;s rMSE. A 50(th) percentile rMSE reduction of respectively 1.87 cm and 2.66 cm is found in the setup.

Highlights

WORK This work investigates the influence of a photodiode (PD) receiver’s angular dependence RP(ψ) on the relation between the photocurrent contribution IPD,i and the receiver-transmitter distance di
Whereas in literature received signal strength (RSS)-based Visible Light Positioning (VLP) systems are only able to ensure accurate localisation through fitting IPD,i − di per light-emitting diode (LED), this paper shows that adequately modelling RP(ψ) via SQ, a proposed function of the square of the incidence angle ψ rather than its cosine, obsoletes this calibrating fit
Incorporating SQ in model-based fingerprinting, improves the p90 by 45.36 cm (83.1%) and 0.84 cm (8.4%) with respect to the ideal m = 1 and generalised mR Lambertian acceptance models for the non-Lambertian-like PDA100A2 while rivalling the mR model’s score for the Lambertian-like PDA36A2

Summary

Introduction

A. INDOOR LOCATION TRACKING The ever-growing degree of automation, in industry, prompts a rapid innovation in indoor localisation. Precise indoor (location) tracking systems should enable a more efficient, more productive and human-safer value chain [1]. A promising indoor tracking application is found in the autonomous 2D navigation of automated guided vehicles (AGVs). Envisioned use cases are e.g. an AGV transporting goods across the factory floor, and an indoor picking robot manoeuvring itself in front of ripe fruit. For highly accurate 2D navigation, most current systems employ either slotted wires embedded in the floor or lasers.

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