Hybrid Dynamics Modeling and Trajectory Planning for Cable-Trailer with Quadruped Robot System
Wentao Zhang, Shaohang Xu, Gewei Zuo, Bolin Li, Jingbo Wang, Lijun Zhu
AI summary
Problem
Motion planning for quadruped-towed cable-trailer systems is hindered by complex hybrid dynamics, nonholonomic trailer constraints, and underactuation, making safe and agile navigation in cluttered environments difficult.
Approach
The authors develop a hybrid dynamics model to capture cable state transitions and propose a two-stage planning framework that uses a hybrid A* search for suboptimal trajectory generation followed by nonlinear optimization with novel geometric polygon collision constraints to refine the path.
Key results
- Hybrid dynamics model capturing taut/slack cable transitions
- Hierarchical planning framework integrating hybrid search with trajectory optimization
- Novel geometric polygon-based collision avoidance constraint for variable-shape dynamics
- Experimental validation on a Unitree A1 demonstrating agile and safe towing
Why it matters
Enables quadruped robots to efficiently transport heavy loads in complex environments, expanding their utility for search-and-rescue and logistics applications.
Abstract
Inspired by sled-pulling dogs in transportation, we present a cable-trailer integrated with a quadruped robot system. The motion planning of this system faces challenges due to the interactions between the cable’s state transitions, the trailer’s nonholonomic constraints, and the system’s underactuation. To address these challenges, we first develop a hybrid dynamics model that captures the cable’s taut and slack states. A search algorithm is then introduced to compute a suboptimal trajectory while incorporating mode transitions. Additionally, we propose a novel collision avoidance constraint based on geometric polygons to formulate the trajectory optimization problem for the hybrid system. The proposed method is implemented on a Unitree A1 quadruped robot with a customized cable-trailer and validated through experiments. The real system demonstrates both agile and safe motion with cable mode transitions.