GNSS Crawler Tutorial
Complete guide to building and operating the GNSS-powered autonomous crawler — featuring PPP RTK 5 cm positioning and a browser-based waypoint programming tool.
What You'll Build
The GNSS Crawler is a compact, highly precise robotic platform designed for autonomous and semi-autonomous operations in both open and confined environments. Unlike larger UGVs, its small footprint allows it to navigate narrow paths, dense terrain, and tight workspaces — achieving up to 5 cm PPP RTK positioning precision without requiring a local base station.
The crawler is configured and programmed through a browser-based online tool that allows users to define waypoints, set mission parameters, and monitor the platform in real time — all from a web browser without any specialist software installation.
Build Overview
Build or Source the Crawler Chassis
Assemble the compact crawler platform with drive motors, wheels, and frame.
Install PPP RTK GNSS Module
Mount the PPP-capable GNSS receiver and configure for PPP correction data input.
Mount the Control Board
Install the main control board (ESP32/STM32/Raspberry Pi) and connect peripherals.
Connect to Correction Stream
Configure the crawler to receive PPP RTK corrections from the PIXAM correction service.
Wire & Test Motors
Wire the motor driver to the control board, verify forward/backward and turning.
Use the Online Programming Tool
Log into the browser-based tool, define your mission waypoints, and upload to the crawler.
Execute First Mission
Arm the crawler, verify PPP lock, and execute your first autonomous waypoint run.
Components List
The GNSS Crawler is built around a compact tracked or wheeled chassis paired with a precision PPP RTK receiver and a lightweight control board. The PPP approach eliminates the need for a local RTK base station, providing global correction access.
| Component | Specification | Purpose |
|---|---|---|
| Compact Crawler Chassis | Small-form tracked or wheeled | Platform structure and drive |
| PPP RTK GNSS Receiver | Multi-constellation, PPP-capable | 5 cm precision positioning |
| GNSS Antenna | Multi-band patch or helix | GNSS signal reception |
| Main Control Board | ESP32 / STM32 / Raspberry Pi | Mission execution and motor control |
| Dual Motor Driver | H-bridge, 5–10A per channel | Drive motor control |
| DC Geared Motors | 12V brushed, with encoders | Wheel / track propulsion |
| LiPo Battery | 3S 11.1V, 5000 mAh | Main power |
| WiFi / LTE Module | ESP32 built-in or 4G modem | PPP correction stream + telemetry |
| IMU | 6-DOF MEMS (MPU-6050 or better) | Heading and attitude sensing |
PPP RTK — How It Works
PPP RTK (Precise Point Positioning — Real Time Kinematic) provides centimetre-level accuracy without a local base station. Instead of comparing to a nearby base, the receiver uses a global network of reference stations to model satellite clock and orbit errors, then applies these corrections to your receiver's measurements.
No Local Base Station
Works anywhere with correction stream access — no need to set up and survey a base station at each site.
Global Coverage
The global correction network provides uniform accuracy worldwide, unlike NTRIP which depends on nearby base stations.
Convergence Time
PPP typically requires 1–5 minutes of convergence time to achieve peak accuracy. Plan missions to allow for this warm-up period.
Multi-Constellation
Receives GPS, Galileo, GLONASS, BeiDou signals simultaneously for robust performance even with partial sky obstruction.
Online Programming Tool
The GNSS Crawler includes access to the PIXAM online programming tool — a browser-based interface for mission planning and real-time monitoring. No software installation required.
Map-Based Waypoint Placement
Click on a map to drop waypoints, define the mission path, and set parameters for each point — speed, arrival radius, and dwell time.
Real-Time Position Display
See the crawler's live GPS position overlaid on the map with heading arrow, accuracy indicator, and battery status.
Parameter Configuration
Adjust mission parameters — maximum speed, turning aggressiveness, and safety geofence — directly from the browser.
One-Click Mission Upload
Once your mission is designed, upload it directly to the crawler over WiFi. The platform immediately arms and is ready to execute.
Mission Logging & Replay
All missions are logged with GNSS track data. Review previous runs, compare against the planned path, and export as KML or CSV.
Emergency Stop Button
Prominent on-screen emergency stop halts the crawler instantly. Manual RC override is always active regardless of connection status.
Platform Capabilities
Compact for Tight Spaces
Navigates paths and environments inaccessible to larger platforms.
5 cm Precision
PPP RTK corrections for centimetre-level real-time positioning.
Multi-GNSS
GPS, Galileo, GLONASS, BeiDou — 4 constellation support.
Waypoint Missions
Full autonomous mission execution with the online programming tool.
Auto & Semi-Auto
Switch between full autonomous, supervised, and manual modes.
Compact & Robust
Durable construction for confined and rough-terrain environments.
Long-Range Link
Maintains stable control and telemetry link across the operating area.
Smart Power
Optimised for extended battery life during autonomous missions.
Live Telemetry
Real-time data logging — position, speed, battery, accuracy.
Geofence Safety
Configurable geofence zone prevents the crawler from leaving the safe area.
Full Build Video
Watch the complete GNSS Crawler build and field demonstration on YouTube — including PPP RTK setup, the online programming tool, and autonomous mission execution.
Build at a Glance
- Difficulty Advanced
- Type Compact Crawler
- Positioning PPP RTK
- Accuracy Up to 5 cm
- Programming Browser-Based Tool
- Corrections Global (no base stn)
- GNSS Systems GPS + Galileo + GLO + BDS
Application Areas
5 cm accuracy. Any location. No base station.
Watch the full build video and explore the GNSS & IoT platform behind the crawler.
Watch on YouTube GNSS & IoT