Safe Swarm Robotics


When designing coordinated controllers for teams of mobile robots, the primary control objective tends to drive the behavior of the team so as to realize tasks such as achieving and maintaining formations, covering areas, or collective transport. Safety, in terms of collision avoidance is added as a secondary controller to override the controller when collision is about to happen. However, there are two major issues with multi-robot collision avoidance algorithms.

  • Collision avoidance is too conservative or even conflicts with the overall goal. The desired team level behavior cannot be achieved.
  • Synthesizing the coordination controller with collision avoidance at the design stage make the problem over complicated. Some of the standard methods to synthesize multi-robot control algorithms become not useful.

This project develops Safety Barrier Certificates which modify the nominal controller in a minimally invasive way so that both the overall objective and collision avoidance can be achieved. Safety is formally guaranteed using control barrier function. The barrier certificates can be executed efficiently by solving a online QP. The effectiveness of this method has been validated on homogeneous/heterogeneous multi-robot platform in both centralized and decentralized fashion.

Video 1: Safe Swarm Robotics

Video 2: Safe Team of Quadrotors

Video 3: Barrier Certificates on Robotarium

Video 4: Barrier Certificates for Safety and Connectivity Maintenence





Li Wang (

Aaron Ames

Magnus Egerstedt


Related Publications:

  • L. Wang, A. Ames, and M. Egerstedt, “Safe Certificate-based Maneuvers for Teams of Quadrotors using Differential Flatness”, 2017 IEEE International Conference on Robotics and Automation (ICRA), to appear, 2017.
  • L. Wang, A. Ames, and M. Egerstedt, “Safety Barrier Certificates for Collisions-free Multi-robot Systems”, IEEE Transactions on Robotics (T-RO), to appear, 2017.
  • L. Wang, A. Ames, and M. Egerstedt, “Multi-objective Compositions for Collision-free Connectivity Maintenance in Teams of Mobile Robots”, 2016 Decisions and Control Conference (CDC), Las Vegas, USA, Dec. 2016.
  • L. Wang, A. Ames, and M. Egerstedt. “Safety Barrier Certificates for Heterogeneous Multi-Robot Systems”, American Control Conference (ACC), Boston, USA, July 2016.
  • U. Borrmann, L. Wang, A. D. Ames and M. Egerstedt, Control Barrier Certificates for Safe Swarm Behavior,  IFAC Conference on Analysis and Design of Hybrid Systems (ADHS), Atlanta, USA, Oct. 2015
  • Pickem, D., Wang, L., Glotfelter, P., Diaz-Mercado, Y., Mote, M., Ames, A., Feron, E. and Egerstedt, M., 2016. Safe, Remote-Access Swarm Robotics Research on the Robotarium. arXiv preprint arXiv:1604.00640.

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