As part of our autonomous drone development for the European Rover Challenge (ERC) 2025, one of the most significant upgrades was the integration of the Ark Flow Sensor. Achieving stable, GPS-independent flight was a core requirement, particularly for indoor missions or metal-structured environments like the ERC flight cage, where GPS signals are unreliable or completely unavailable.

Why Optical Flow?

Optical flow sensors determine motion by analysing the displacement of features between successive image frames. When paired with distance data, this enables a drone to accurately estimate its horizontal movement relative to the ground. While traditional solutions, such as the PMW3901 combined with an external rangefinder, can achieve this, they often suffer from poor accuracy and complex integration requirements.

Introducing the Ark Flow

The Ark Flow sensor from Ark Robotics delivers a compact, reliable, and fully integrated solution. It combines an optical flow camera with a high-performance distance sensor capable of measuring altitudes from as low as 80 mm up to 30 m. It performs reliably even in low-light conditions and communicates via the UAVCAN protocol, making it an ideal match for our PX4-based flight controller.

Key Technical Advantages

• Compact Design: Easy to mount, even on space-limited frames.
• Integrated Distance Sensing: Removes the need for additional Lidar.
• PX4 & UAVCAN Compatible: Simplifies integration and configuration.
• Reliable up to 25 m height and 7.4°/s angular velocity.

With the Ark Flow providing consistent, low-latency position feedback, our drone now hovers more stably and navigates more precisely than before. This represents a major improvement over last year’s platform, which often struggled with positional drift and unreliable altitude estimation. Thanks to this upgrade, we’re one step closer to achieving fully autonomous and dependable drone operations for the ERC.