About

For UAV take-off, tether and landing, FMCW mmWave radar offers a compelling combination of fundamental advantages:

• Low SWaP — enabling compact, lightweight and power-efficient integration.
• High precision — providing the range and motion accuracy required for repeatable autonomous operations.
• Resilience in challenging conditions — maintaining sensing capability through rain, fog, dust and other conditions that can degrade optical systems.
• Low dependence on visibility and ambient illumination — reducing susceptibility to the limitations and interference associated with vision-based approaches.

Our initial work used traditional radar techniques and demonstrated the underlying promise of radar-based landing and docking. However, we identified a fundamental limitation when applying conventional radar to the most demanding parts of the problem.

Traditional approaches typically infer the presence and identity of a landing or tether point from observed patterns, signatures or correlations. In effect, this introduces a confidence-based decision: the system determines that what it is seeing is sufficiently consistent with the expected target.

For safety-critical autonomous operations, we wanted something fundamentally different.

Rather than asking the radar to infer that an anchor point is present, we developed and patented Active Radar Co-operation (ARC™) — an end-to-end cooperative radar architecture in which the airborne and anchor-side radar systems actively participate in establishing the relationship.

This makes ARC™ more analogous to an RF communications system than to a conventional radar target-recognition problem.

The anchor can be:

• Identified — the system can establish which cooperative anchor it is interacting with.
• Authenticated — the airborne system can verify that the response originates from the intended cooperative anchor rather than simply matching an observed physical pattern.

The result is a fundamentally different approach to the final stages of autonomous UAS operation: the aircraft does not merely recognise an anchor; it cooperates with it.

Importantly, ARC™ does not require the radar hardware to become a single-purpose landing sensor.

Away from cooperative anchor units, the same radar-based transceivers retain conventional downward-facing radar capabilities, supporting functions including:

• Obstacle detection
• Altimetry
• Odometry / motion estimation

This creates a single radar sensing platform capable of supporting the UAS across the operational cycle — from navigation and flight through to the highly constrained and safety-critical phases of take-off, tether engagement and landing.

In short, ARC™ combines the inherent environmental resilience and precision of FMCW mmWave radar with an active cooperative architecture, transforming radar from a system that recognises a landing point into one that can establish, verify and interact with a known anchor point.