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Antenna system for trilateral drone precise vertical landing

Víctor Araña-Pulido, Eugenio Jiménez-Yguácel, Francisco Cabrera-Almeida, Pedro Quintana-Morales

TL;DR

The paper tackles the challenge of autonomous precision vertical landings for drones by introducing a trilateral RF phase-shift system, where a landing-point transmitter and a drone-mounted tri-antenna perform phase-difference measurements to continuously guide the drone toward the landing point. The authors provide a detailed antenna design, including a circularly polarized LP antenna and three linearly polarized drone elements, and derive how tracking area, ADC resolution, and polarization affect performance, with an inter-element spacing of $D=7$ cm. An Arduino-based control system and a simple detector-zeroing calibration enable real-time corrections, achieving an average update rate exceeding $300$ Hz and robust operation in both near- and far-field conditions. Experimental results demonstrate tracking radii up to about $4.99$ m at $z_D=10$ m, an AR-induced power variation of only $\leq0.35$ dB, and an RF dynamic range of around $28$ dB, establishing the method as a viable high-ODR alternative to image or GPS-based landing approaches for autonomous drone precision landings.

Abstract

This article presents a radio frequency system that can be used to perform precise vertical landings of drones. The system is based on the three-way phase shift detection of a signal transmitted from the landing point. The antenna system is designed by taking into account parameters such as landing tracking area, analog-to-digital converter (ADC) resolution, phase detector output range, antenna polarization, and the effect of antenna axial ratio. The fabricated prototype consists of a landing point antenna that transmits a signal at 2.46 GHz, as well as a drone triantenna system that includes a phase shift detection circuitry, ADC, and a simple control program that provides the correction instructions for landing. The prototype provides an averaged output data rate (ODR) suitable for landing maneuvers (>300 Hz). A simple system calibration procedure (detector output zeroing) is performed by aligning the antenna system. The measurements performed at different altitudes demonstrate both the correct operation of the proposed solution and its viability as an instrument for precision vertical landings.

Antenna system for trilateral drone precise vertical landing

TL;DR

The paper tackles the challenge of autonomous precision vertical landings for drones by introducing a trilateral RF phase-shift system, where a landing-point transmitter and a drone-mounted tri-antenna perform phase-difference measurements to continuously guide the drone toward the landing point. The authors provide a detailed antenna design, including a circularly polarized LP antenna and three linearly polarized drone elements, and derive how tracking area, ADC resolution, and polarization affect performance, with an inter-element spacing of cm. An Arduino-based control system and a simple detector-zeroing calibration enable real-time corrections, achieving an average update rate exceeding Hz and robust operation in both near- and far-field conditions. Experimental results demonstrate tracking radii up to about m at m, an AR-induced power variation of only dB, and an RF dynamic range of around dB, establishing the method as a viable high-ODR alternative to image or GPS-based landing approaches for autonomous drone precision landings.

Abstract

This article presents a radio frequency system that can be used to perform precise vertical landings of drones. The system is based on the three-way phase shift detection of a signal transmitted from the landing point. The antenna system is designed by taking into account parameters such as landing tracking area, analog-to-digital converter (ADC) resolution, phase detector output range, antenna polarization, and the effect of antenna axial ratio. The fabricated prototype consists of a landing point antenna that transmits a signal at 2.46 GHz, as well as a drone triantenna system that includes a phase shift detection circuitry, ADC, and a simple control program that provides the correction instructions for landing. The prototype provides an averaged output data rate (ODR) suitable for landing maneuvers (>300 Hz). A simple system calibration procedure (detector output zeroing) is performed by aligning the antenna system. The measurements performed at different altitudes demonstrate both the correct operation of the proposed solution and its viability as an instrument for precision vertical landings.
Paper Structure (10 sections, 2 equations, 14 figures, 1 table)

This paper contains 10 sections, 2 equations, 14 figures, 1 table.

Table of Contents

  1. Introduction
  2. Triangular Phase Shift Landing System
  3. Antenna System Design
  4. Tracking area, ADC resolution and distance between antennas
  5. Antenna polarizations
  6. Anntena system
  7. Axial Ratio vs. Drone Location
  8. Control System
  9. Experimental Evaluation
  10. Conclusions

Figures (14)

  • Figure 1: (a) Coordinate system of the drone and $LP$ reception points. (b) Tracking area when the drone altitude is 220, 46, 31 and 16 cm, the receiving points are separated $D$ = 7 cm, $f$ = 2.46 GHz and non-ambiguous range of $\pm$80º in the multiplier analog detector is considered.
  • Figure 2: Correction maneuvers based on the phase shift information between drone receiving points.
  • Figure 3: Array design parameters as a function of the distance between receiving points ($D$): Maximum (blue) and minimum (red) tracking distance, detector sensitivity in mV/cm (black) and ADC sensitivity in cm/step (cyan) for 8, 10 and 12 bit resolution ($\Delta V_d$ = 2.6 V, $f$= 2.46 GHz, $z_D$ = 10 m and $D$ = 7 cm).
  • Figure 4: Tri-antena array for drone landing system: $L$ = 15 cm and $D$ = 7 cm.
  • Figure 5: (a) Drone and $LP$ antennas. Dimensions in mm: Linearly polarized antenna: $W\!p$ = 32.4, $Lp$ = 24.2, $Si$ = 9.2, $Sg$ = 0.6, $W\!f$ = 2.2. (b) Circularly polarized antenna: $W$ = 23.5, $Ws$ = 1.0, $Ls$ = 6.5, $X\!f$ = 7.8, $Y\!f$ = 7.8.
  • ...and 9 more figures