Swept Volume-Based Continuous Object Gathering Trajectory Generation for Tethered Robot Duo

Abstract

We propose a continuous gathering scheme based on the swept volume to address the challenges involved in planning a tethered robot duo to efficiently collect marine debris. Specifically, we model the tethered robot duo by constructing a double-layer U-shape, and then apply an object-aware optimization approach that leverages the swept volume signed distance field (SVSDF) to guide trajectory optimization, promoting complete object collection while maintaining a continuous and collision-free gathering motion. Existing algorithms either fail to fully address key challenges, such as assuming an unrealistically infinite tether length or incurring high computational costs. In contrast, our proposed method, by adopting the double-layer U-shape technique, effectively manages tether length constraints and preserves the tether shape, ensuring feasible collection. By utilizing the SVSDF technique to guide the trajectory optimization process, we maximize the swept coverage of objects while minimizing that of obstacles. This enables complete object coverage, avoids collisions, and prevents the tether from becoming trapped by obstacles during the collection process. Moreover, we propose a set of metrics for this gathering planning problem and validate the generated trajectories in simulation, using a collision-free multi-UAV information-gathering approach to efficiently estimate the target area. Simulations demonstrate that our proposed method achieves superior, resolution-independent gathering performance compared to existing algorithms.