Navigation of non-communicating autonomous mobile robots with guaranteed connectivity

Abstract

We consider the connectivity of autonomous mobile robots. The robots navigate using simple local steering rules without requiring explicit communication among themselves. We show that using only position information of neighbors, the group connectivity can be sustained even in the case of bounded position measurement errors and the occlusion of robots by other robots in the group. In implementing the proposed scheme, sub-optimal solutions are invoked to avoid an excessive computational burden. We also discuss the possibility of deadlock which may bring the group to a standstill and show that the proposed methodology avoids such a scenario in real-life settings

Leader–Follower Navigation in Obstacle Environments While Preserving Connectivity Without Data Transmission

“…The leader-follower navigation algorithm in [20] decides the direction of movement using an artificial potential function, then the amount of movement is determined taking into account the input constraint and network connectivity. We also use this basic procedure in our proposed method.…”

“…We also use this basic procedure in our proposed method. However, [20] did not consider obstacle environments and inter-robot collisions. To overcome this limitation, we derive additional constraints on the amount of movement so as to achieve LOS visibility preservation, obstacle avoidance and inter robot collision avoidance.…”

“…If the condition in (20) and the collision avoidance condition in (2) are satisfied, it is guaranteed that the links (j, m) and (m, i) of the robots (i, j, m) satisfying (21) will not be deactivated, as shown in Lemma 3 in Appendix A. Therefore, the network connectivity is preserved at least if N = 3, i.e., if there are no robots other than (i, j, m).…”

“…We introduce a simple rule to change network topology depending on environments in such a way that some sensing links are deactivated in order to pass through narrow spaces while active links are increased in free spaces to keep the group as cohesive as possible. Furthermore, unlike many other studies including [20], the effectiveness of the algorithm is demonstrated not only with simulations, but also in real robot experiments.…”

“…Unlike most connectivity-preserving algorithms, the control input is determined so as not only to guarantee connectivity preservation and collision avoidance, but also to ensure that a given input constraint is not violated at each time step. Although an input constraint is considered in the connectivity-preservation algorithm for the leader-follower navigation proposed in [20], it has limitations in that an obstacle-free environment is assumed and that collision avoidance is not guaranteed. In obstacle environments, the proposed method manages control input so as to preserve line-of-sight (LOS) visibility between neighbors as well as a maximum distance constraint.…”