Vision-Based Multirotor Control for Spherical Target Tracking: A Bearing-Angle Approach

2025-06-20

AI Summary

Tracking fast-moving spherical targets with unknown radius using multirotor UAVs remains challenging without depth sensors or prior knowledge of target size. Method: This paper proposes a vision-based servoing approach that constructs a bearing-angle coordinate system derived solely from camera-measured 2D azimuth angles, mapping pure bearing measurements to geometric quantities indicative of relative distance. An adaptive nonlinear controller is then designed within this coordinate system, integrating a constant-acceleration target motion model with camera geometric constraints. Contribution/Results: The method achieves stable and convergent tracking even under highly dynamic target motion and complete uncertainty in target radius—without requiring position or depth estimation. Simulation results demonstrate significantly lower tracking errors compared to conventional vision-servoing methods reliant on such estimates. This work establishes a new paradigm for passive, resource-constrained target tracking in aerial robotics.

Technology Category

• Computer Vision: Motion & Tracking
• Intelligent Robots: State Estimation
• Humans and AI: Human-Aware Planning and Behavior Prediction

Application Category

• Security and Privacy: Tracking, profiling, and countermeasures against them
• User Modeling, Personalization and Recommendation: Fairness-aware retrieval and ranking
• Responsible Web: Machine-in-the-loop, human agency and autonomy

Abstract

This work addresses the problem of designing a visual servo controller for a multirotor vehicle, with the end goal of tracking a moving spherical target with unknown radius. To address this problem, we first transform two bearing measurements provided by a camera sensor into a bearing-angle pair. We then use this information to derive the system's dynamics in a new set of coordinates, where the angle measurement is used to quantify a relative distance to the target. Building on this system representation, we design an adaptive nonlinear control algorithm that takes advantage of the properties of the new system geometry and assumes that the target follows a constant acceleration model. Simulation results illustrate the performance of the proposed control algorithm.

Problem

• Design visual servo controller for multirotor tracking spherical target
• Transform bearing measurements into bearing-angle pair for dynamics
• Develop adaptive nonlinear control for target with constant acceleration

Innovation

• Transforms bearing measurements into bearing-angle pairs
• Derives system dynamics in new coordinates
• Designs adaptive nonlinear control algorithm