Drone Localization Pipeline

This page explains how the drone (VOXL‑powered UAV) generates localization data, formats it, and streams it wirelessly to the rover or operator PC.

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Overview

The drone uses:

• VOXL2 onboard computer
• Visual‑Inertial Odometry (VIO) via voxl-qvio-server
• UDP streaming to send pose information (x, y, quality, reset flag)

This localization pipeline allows the rover to follow the drone or move to its commanded position.

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Localization Data Flow

VOXL Cameras + IMU
        ↓
OpenVINS / QVIO
        ↓
voxl-inspect-qvio (real‑time stream)
        ↓
Python script on VOXL
        ↓ UDP →
Laptop / Rover Computer

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Data Format

Every localization packet sent from the drone has:

timestamp, x, y, msg, quality, reset_flag

Example:

1738532812.221, -0.120, 0.055, FOLLOW, 92, 0

Field	Meaning
timestamp	Unix time
x,y	Drone position in meters (VIO local frame)
quality	VIO tracking quality (0–100%)
reset_flag	1 when VIO resets, 0 otherwise

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Reset Behavior

QVIO can reset when visual tracking is lost (e.g., occlusion, low light).
When this happens:

• VOXL sets reset_flag = 1
• Drone position jumps to (0,0)
• Rover performs a graceful reset (finish last movement → return to origin)

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Script Running on the Drone (Sender)

python3 send_vio_udp.py

This script: Reads VOXL VIO data
Sends UDP packets to PC/rover
Supports user input for Come‑To‑Me mode trigger

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Testing VIO on the Drone

Before streaming, verify VIO works:

voxl-inspect-qvio

Expected:

T_imu_wrt_vio (m) | quality | state
-0.02 0.05 -0.01  |  93%    | OKAY

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Notes

• Best performance with textured environments and good lighting
• Low quality values (<20) trigger safe behavior
• Works without GPS (indoor‑friendly)

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