Multi-agent flocking with noisy anchor-free localization

In this paper we focus on radio-based navigation of an autonomous dynamic swarm system of agents. We assess the anchor-free localization and investigate the impact of the performance of localization to a swarm flocking algorithm. Low latency is crucial in a dynamic autonomous swarm system to control the formation of the swarm. Therefore, an agent applies the randomized orthogonal frequency-division multiple access (OFDMA) scheme to range with multiple neighbours simultaneously by round-trip delay (RTD). The connectivity level and the ranging accuracy are the main factors affecting the localization accuracy. These two factors are coupled through the limited available spectrum. On the one hand high connectivity between agents is needed to guarantee a unique localization solution. On the other hand with a fixed amount of total spectrum the possible spectrum for each connected link decreases with the increasing number of connected agents. Therefore, the ranging accuracy between agents decreases. We investigate the relationship between the rigidity matrix and the location Cramér-Rao bound (CRB). We modify the location CRB (MCRB) with the ranging Ziv-Zakai bound (ZZB) and apply the MCRB as a noisy localization model in the flocking algorithm. Our preliminary study shows that the proposed swarm navigation system performs well under the condition that the localization error is considered in the flocking algorithm.