# Autonomous UAV Landing and Collision Avoidance System for Unknown Terrain Utilizing Depth Camera with Actively Actuated Gimbal

## TL;DR

This paper introduces a system for autonomous UAV landing and obstacle avoidance using an RGB-D camera on an actively actuated gimbal, enabling safe flight in unknown terrain.

## Contribution

The novelty lies in combining gimbal actuation with RGB-D sensing for improved obstacle detection and landing in unprepared environments.

## Key findings

- The system successfully detected obstacles and enabled safe landing in simulation and static real-world tests.
- The gimbal's active actuation improved the field of view and depth perception for low-altitude flight.
- The proposed architecture is shown to be deployable in real-world conditions.

## Abstract

Autonomous landing capability is crucial for fully autonomous UAV flight. Currently, most solutions use either color imaging from a camera pointed down, lidar sensors, dedicated landing spots, beacons, or a combination of these approaches. Classical strategies can be limited by either no color data when lidar is used, limited obstacle perception when only color imaging is used, a low field of view from a single RGB-D sensor, or the requirement for the landing spot to be prepared in advance. In this paper, a new approach is proposed where an RGB-D camera mounted on a gimbal is used. The gimbal is actively actuated to counteract the limited field of view while color images and depth information are provided by the RGB-D camera. Furthermore, a combined UAV-and-gimbal-motion strategy is proposed to counteract the low maximum range of depth perception to provide static obstacle detection and avoidance, while preserving safe operating conditions for low-altitude flight, near potential obstacles. The system is developed using a PX4 flight stack, CubeOrange flight controller, and Jetson nano onboard computer. The system was flight-tested in simulation conditions and statically tested on a real vehicle. Results show the correctness of the system architecture and possibility of deployment in real conditions.