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This article proposes a mutual positioning relay method that enables multiple robots to monitor indoor environments. Here, robots refer to a small number of parent robots with high positioning performance and a large number of child robots with minimal positioning performance. The parent robot can estimate its state accurately by itself. In comparison, the child robots have position errors that accumulate with time as they use only odometry information for positioning. Each robot can recognize other robots in its field of view by using a depth camera. It then performs relative positioning and estimates its position of itself or that of other robots on the map. The uncertainty of the position estimation is compared with each other, and the robot with a certain position becomes a positioning reference for the robot with an uncertain position. In this way, both the parent and child robots relay relative positioning with each other, following which all the robots accurately estimate their positions. In this study, six robots based on Roomba were used. The performance of the proposed method was verified based on experimental data of autonomous navigation tests. Our results showed that the proposed method could realize an accuracy that was four to five times better than that performed independently by a child robot. Our findings also revealed that the proposed method can recover the failure of the state estimation of the parent robot.

Genetic mechanisms underlying the acquisition of new traits are an important topic in evolutionary developmental biology. Especially, the co-option of important regulatory genes potentially plays an important role in the gain of new traits. However, how the co-option occurs at the sequence level is still elusive.Drosophila guttiferahas a unique wing pigmentation pattern and this is newly gained via the evolution of the expression pattern ofwingless, which induces the pigmentation pattern formation. In this study, to reveal the changes in thecis-regulatory sequence which caused the co-option ofwinglessthat lead to the expression in a new place, we conducted transgenic EGFP reporter assays of alteredcis-regulatory sequences. As a result, the sequence was divided into regions needed to activate expression in the entire wing veins and a region required for repressing expression in excess parts. Comparisons with the homologous sequence ofDrosophila melanogastershowed that the repressive function of thecis-regulatory region is also possessed byD. melanogasterwhile the activating function is newly gained in a lineage leading toD. guttifera. Furthermore, a putative binding site of SMAD transcription factors is shown to be essential for activating expression but also existing in the homologous region ofD. melanogaster. Our results suggest that the pre-existing regulatory sequences in thecis-regulatory region coordinate with the newly gained sequences to acquire the new expression pattern ofwingless.Graphical Abstract

The co‐option of regulatory genes has the potential to play an important role in the evolutionary gain of new traits. However, the changes at the sequence level that underlie such a co‐option event are still elusive. We identified the changes in the cis‐regulatory sequence of wingless that caused co‐option of wingless and led to its expression in new places in Drosophila guttifera, which has unique pigmentation patterns on its wings. The newly gained function of gene expression activation was acquired evolutionarily via a combination of pre‐existing sequences containing a putative binding site for SMAD transcription factors that exhibit an ancestral function in driving expression at crossveins, and a sequence that is specific to the lineage leading to D. guttifera.