  Ultra-wideband (UWB) localization methods have emerged as a cost-effective
and accurate solution for GNSS-denied environments. There is a significant
amount of previous research in terms of resilience of UWB ranging, with
non-line-of-sight and multipath detection methods. However, little attention
has been paid to resilience against disturbances in relative localization
systems involving multiple nodes. This paper presents an approach to detecting
range anomalies in UWB ranging measurements from the perspective of multi-robot
cooperative localization. We introduce an approach to exploiting redundancy for
relative localization in multi-robot systems, where the position of each node
is calculated using different subsets of available data. This enables us to
effectively identify nodes that present ranging anomalies and eliminate their
effect within the cooperative localization scheme. We analyze anomalies created
by timing errors in the ranging process, e.g., owing to malfunctioning
hardware. However, our method is generic and can be extended to other types of
ranging anomalies. Our approach results in a more resilient cooperative
localization framework with a negligible impact in terms of the computational
workload.
