Agent and link redundancy for autonomous formations

More and more often the multiagent formations found in high-risk military and civilian missions are designed to sustain the loss of some agents or control/communication links. In a military context, the agent loss could be a result of enemy attack and/or mechanical breakdown, while the link loss is usually due to enemy jamming, reduced transmission power, obstacles and/or hardware failure. If the agents are tasked to tightly maintain their inter-agent distances in order to maintain a desirable shape of the formation, loss of certain agents or links could lead to catastrophic consequences. This preliminary work proposes to address this potential problem by enforcing redundancy in the formation design, by addition of extra agents and/or links beyond the minimum necessary. Following an existing graphical model of the formations, we extend the notions and definitions for simple rigidity to ones including the redundancy concept. We remark that this engineered redundancy naturally reflects a level of operational robustness/health of the formation. We differentiate the measure into a deterministic metric and a statistical metric, and provide some general results on redundant rigidity.