[Paper Review] Traffic Management Strategies for Multi-Robotic Rigid Payload Transport Systems

Yahnit Sirineni, Pulkit Verma+1 more|arXiv (Cornell University)|Jun 27, 2019

Robotic Path Planning Algorithms27 references4 citations

TL;DR

This paper proposes a decentralized leader-follower-ORCA-RRT* framework for traffic management in multi-robot rigid payload transport systems, using modified nh-ORCA for collision avoidance and RRT* for path planning. The system ensures collision-free, formation-stable transport of multiple payloads across dynamic environments with obstacles, demonstrating scalability and minimal path deviation in simulations with up to 30 systems.

ABSTRACT

In this work, we address traffic management of multiple payload transport systems comprising of non-holonomic robots. We consider loosely coupled rigid robot formations carrying a payload from one place to another. Each payload transport system (PTS) moves in various kinds of environments with obstacles. We ensure each PTS completes its given task by avoiding collisions with other payload systems and obstacles as well. Each PTS has one leader and multiple followers and the followers maintain a desired distance and angle with respect to the leader using a decentralized leader-follower control architecture while moving in the traffic. We showcase, through simulations the time taken by each PTS to traverse its respective trajectory with and without other PTS and obstacles. We show that our strategies help manage the traffic for a large number of PTS moving from one place to another.

Motivation & Objective

• To address the challenge of coordinating multiple rigid payload transport systems (PTS) in shared environments with obstacles.
• To ensure collision avoidance between multiple PTS and static obstacles while maintaining formation integrity.
• To enable efficient, scalable, and decentralized navigation for multiple PTS toward individual goals.
• To minimize path deviation and ensure timely delivery despite traffic and environmental constraints.

Proposed method

• Uses RRT* to compute optimal trajectories for the leader of each PTS from source to destination, considering static obstacles.
• Applies a modified nh-ORCA algorithm to compute collision-free linear and angular velocities for the leader in real time.
• Employs a decentralized leader-follower control law to compute follower velocities, preserving formation geometry.
• Interpolates the leader’s path into waypoints to guide the entire formation while maintaining desired distances and angles.
• Integrates obstacle and inter-formation collision avoidance by dynamically adjusting velocities based on relative positions and predicted trajectories.
• Validates the framework through extensive simulations with varying formation shapes, obstacle counts, and system scales.

Experimental results

Research questions

• RQ1 How can multiple rigid payload transport systems be coordinated to avoid collisions with each other and static obstacles in a shared environment?
• RQ2 To what extent can a decentralized control architecture maintain formation integrity while enabling collision-free navigation in dense traffic?
• RQ3 How does the inclusion of obstacles affect the time-to-destination and path deviation of PTS compared to obstacle-free scenarios?
• RQ4 Can the proposed framework scale effectively to large numbers of PTS without compromising safety or performance?

Key findings

• The system successfully navigated 30 PTS across complex environments with static obstacles, achieving collision-free operation without formation breakdown.
• Time-to-destination in obstacle-rich environments was comparable to obstacle-free scenarios, indicating efficient path planning and minimal detour.
• Each PTS maintained a consistent follower-to-leader distance of approximately 0.35m, even during collision avoidance maneuvers.
• The modified nh-ORCA algorithm enabled dynamic velocity adjustments that prevented collisions with neighboring formations and obstacles, as evidenced by velocity changes at critical proximity points.
• The minimum inter-formation distance was preserved at all times, confirming robust inter-formation collision avoidance.
• The system demonstrated strong scalability, maintaining performance and safety with increasing numbers of PTS in simulation.