Electric UGV Active RTK GNSS Electric Drive

KNOX Build Tutorial

Complete guide to building the KNOX electric 4-wheel UGV, from mechanical assembly and wiring to RTK GNSS setup and autonomous waypoint navigation.

Jump to: Overview Components Assembly RTK Setup Navigation Build Video

What You'll Build

KNOX is an electric-powered 4-wheeled Unmanned Ground Vehicle (UGV) designed for precision autonomous operation. Originally developed as an autonomous grass-cutting platform, KNOX combines electric drive motors, GNSS RTK positioning, and programmable waypoint navigation into a single field-ready machine capable of achieving centimetre-level accuracy.

The platform supports two operating modes: full manual RC control and fully autonomous waypoint navigation. In autonomous mode, KNOX follows a pre-programmed route with repeatable sub-centimetre accuracy, making it ideal for agricultural, landscaping, and research deployments.

<1 cm

RTK Accuracy

4-Wheel

Electric Drive

Dual Mode

Manual & Auto

Build Overview

Source the Chassis

Obtain or build the 4-wheel electric drive platform chassis and motor assembly.

Install Flight Controller

Mount the ArduPilot-compatible flight controller that manages autonomous navigation.

Mount GNSS RTK Module

Install the GNSS receiver and RTK correction antenna for centimetre positioning.

Configure RTK Base / NTRIP

Set up RTK corrections via a base station or NTRIP service for sub-cm accuracy.

Wire Electronics

Connect motors, ESCs, controller, GNSS, RC receiver, and power distribution.

Configure ArduPilot

Tune the KNOX parameters, calibrate sensors, and verify motor mixing.

Program Waypoints & Test

Define an autonomous mission, verify RTK lock, and execute your first autonomous run.

Components List

KNOX is built around a brushed or brushless 4-wheel electric chassis combined with an ArduPilot-compatible autopilot and a high-precision GNSS RTK receiver.

Component	Specification	Purpose
4WD Chassis	Electric UGV frame with motor mounts	Platform base and drive
Brushless Motors	Outrunner motors (×4) with encoders	Wheel propulsion
ESC	20–30A brushless ESC (×4)	Motor speed control
Autopilot Board	Pixhawk 4 / Cube Orange / Ardupilot	Navigation & control
GNSS RTK Receiver	u-blox F9P or equivalent	Sub-cm positioning
RTK Antenna	Survey-grade helical or patch	GNSS signal reception
RC Receiver	SBUS/PPM compatible (≥6 channels)	Manual control override
LiPo Battery	4S–6S 10,000–20,000 mAh	Main power supply
Power Distribution	PDB with current sensor	Power distribution & monitoring
Telemetry Radio	433 MHz or 915 MHz pair	GCS real-time link
Onboard Computer	Raspberry Pi 4 (optional)	Mission planning & logging

Mechanical Assembly

Chassis Construction

Assemble the 4WD chassis frame according to the platform's documentation. Ensure motor mounts are aligned and square. Use thread-lock compound on all critical fasteners that may be exposed to vibration.

Electronics Bay

Mount the autopilot board on a vibration-dampening plate at the centre of mass. Use foam or O-ring standoffs to isolate the IMU from motor vibrations. Keep the board level to within 1° for accurate AHRS.

GNSS Antenna Placement

Mount the RTK antenna on a ground plane (metal plate) at the highest point of the platform, away from motors and ESCs. Run the coax cable away from power wires to minimise interference.

Telemetry & RC Antennas

Position telemetry antennas vertically for maximum omnidirectional gain. Ensure RC receiver antennas are separated by 90° for diversity reception.

RTK GNSS Setup

RTK (Real-Time Kinematic) positioning achieves centimetre accuracy by comparing phase measurements from a fixed base station with your rover receiver. Follow these steps to configure your RTK system:

Configure the F9P Rover

Connect the u-blox F9P to your autopilot via UART. Configure the baud rate (115200), output messages (RTCM3 + UBX NAV-PVT), and set rover mode in u-center.

Set Up RTK Corrections

Subscribe to an NTRIP correction service (e.g., national correction network) or deploy your own F9P base station surveyed to a known point.

Configure ArduPilot GPS

In Mission Planner, set GPS_TYPE to ublox, enable RTCM injection, and verify RTK float → RTK fixed lock in the GPS status panel.

Verify Accuracy

With RTK Fixed lock, accuracy drops to ≤1 cm. Confirm by comparing GPS coordinates against a known survey marker. Walk the rover and verify positional consistency.

RTK Fixed vs Float: Float gives ~30–50 cm accuracy; Fixed gives ≤1 cm. Always wait for RTK Fixed lock before starting an autonomous mission. Time to fix depends on sky view and correction latency, typically 30–120 seconds.

Waypoint Navigation

KNOX uses the ArduPilot Rover firmware and Mission Planner GCS to define and execute autonomous waypoint missions. The system supports complex mission profiles including coverage patterns, turn radius limits, and speed profiles.

Mission Planning

Use Mission Planner's Flight Plan tab to place waypoints on the map. Set vehicle speed, turn radius, and arrival radius for each waypoint. Upload the mission to KNOX before arming.

Real-Time Monitoring

Monitor KNOX in real time via the telemetry link in Mission Planner, view live position, speed, battery voltage, RTK status, and remaining mission waypoints.

Repeatable Accuracy

Thanks to RTK Fixed positioning, KNOX can re-execute the same mission with sub-centimetre repeatability, essential for precision agriculture row coverage.

Safety Features

ArduPilot's failsafe system returns KNOX to home if RC link or telemetry is lost. Manual override is always available via the RC transmitter.

Before Your First Autonomous Run: Always test manual control first, verify RTK Fixed lock, check failsafes, and have a spotter. Begin with a simple 4-point rectangular mission at slow speed before attempting complex coverage patterns.

Full Build Video

Watch the complete KNOX build on YouTube, covering the mechanical assembly, electronics integration, RTK GNSS configuration, and first autonomous field run.

Build at a Glance

Difficulty Advanced
Type 4-Wheel UGV
Controller ArduPilot / Pixhawk
Positioning GNSS RTK
Accuracy <1 cm RTK Fixed
Drive Brushless Electric
Navigation ArduPilot Waypoints

Key Capabilities

Sub-centimetre RTK accuracy
Autonomous waypoint missions
Manual RC override always available
Real-time telemetry monitoring
ArduPilot failsafe protection
Precision agriculture ready

Watch Build Video KNOX Project Page All Tutorials

Build autonomous precision with KNOX.

Watch the full build video, subscribe for Part 2, and follow the GNSS & IoT guide.

Watch on YouTube GNSS & IoT