Decentralized Motion Coordination and Team Coherence
Approach and Motivation
In relation to the above challenge, this work focuses on providing collision avoidance and completeness guarantees for multiple autonomous vehicles operating in the same obstacle-free space. The vehicles have to move from distinct, non-overlapping start configurations to their goals. These goals may be potentially overlapping but once a vehicle reaches its goal, it is no longer part of the coordination problem. For example: a scenario where multiple aircraft coordinate when flying at constant altitude. When an airplane reaches the vicinity of an airport, it initiates its landing maneuver and no longer constrains the remaining aircraft.
Extended Roundabout Policy for 60 Agents with 60 Different Targets
Generalized Roundabout Policy (GRP) vs Extended Roundabout Policy (ERP)
Landing Scenario using Extended Roundabout Policy (ERP)
Approach and Motivation
Many multi-agent applications may involve a notion of spatial coherence. For instance, simulations of virtual agents often need to model a coherent group or crowd. Alternatively, robots may prefer to stay within a pre-specified communication range.
This paper proposes an extension of a decentralized, reactive collision avoidance framework, which defines obstacles in the velocity space, known as Velocity Obstacles (VOs), for coherent groups of agents. The extension, referred to in this work as a Loss of Communication Obstacle (LOCO), aims to maintain proximity among agents by imposing constraints in the velocity space and restricting the set of feasible controls.
If the introduction of LOCOs results in a problem that is too restrictive, then the proximity constraints are relaxed in order to maintain collision avoidance. If agents break their proximity constraints, a method is applied to reconnect them. The approach is fast and integrates nicely with the Velocity Obstacle framework. It yields improved coherence for groups of robots connected through an input constraint graph that are moving with constant velocity.
Simulated environments involving a single team moving among static obstacles, as well as multiple teams operating in the same environment, are considered in the experiments and evaluated for collisions, computational cost and proximity constraint maintenance. The experiments show that improved coherence is achieved while maintaining collision avoidance, at a small computational cost and path quality degradation.
Although VOs are not designed to maintain coherence of agents, it is still the most relevant method to compare against, due to both approaches being decentralized and sharing the exact same information constraints.
- Krontiris A., Bekris K E., "Using Minimal Communication to Improve Decentralized Conflict Resolution for Non-holonomic Vehicles", IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS-11), San Francisco, CA, Sept., 2011.
- Kimmel A., Dobson A., Bekris KE.. Maintaining Team Coherence under the Velocity Obstacle Framework, Eleventh International Conference on Autonomous Agents and Multiagent Systems (AAMAS), Valencia, Spain, June, 2012.
This work has been supported by NSF CNS 0932423. Any opinions and findings expressed in this paper are those of the authors and do not necessarily reflect the views of the sponsor.