Principles of Biological and Robotic Navigation

The BioNav workshop was held at the MPIPKS in Dresden from August 29 to August 31, 2016. The workshop was special in its cross-disciplinary focus and format, as it brought together physicists, mathematicians, biologists, and robotic engineers interested in principles of navigation. The common theme was the reliable control of directional motion in response to environmental cues with sparse computational resources.

After welcoming words by Frank Julicher, the workshop started with sessions on ‘sensori-motor coupling’ and ‘mechanisms of gradient-sensing’. We highlight a few of the contributions to the workshop. Massimo Vergassola gave a key note lecture on gradient sensing in turbulent environments and their information-theoretic basis. These concepts were applied to both pheromone-guide navigation of moths and mobile robots that had to find the maximum of an odor plume distorted by turbulent air flow.

Matthieu Louis demonstrated a chemotaxis mechanism of Drosophila larvae based on head casting, which remains operative even if all but one sensory neurons are deactivated.

Gaspar Jekely discussed three different phototactic steering strategies in Platynereis larvae and linked those to the neuronal connectome in these larvae. Luis Alvarez presented impressive 3D-tracking data of navigating sperm cells, revealing a distinct chemotaxis strategy along helical paths. Interestingly, all these three biological navigation strategies rely on active exploratory motion of the swimmer themselves, whereby a spatial stimulus is converted into a temporal signal. This concept is known as ‘information self-structuring’ in the robotics field, and was the topic of the talk by Fumiya Iida.

Barbara Webb impressively combined both topics of the workshop in her talk: she presented experimental data on path-learning in ants, together with a computational model of vector integration that turned out to match the neuronal morphology of the relevant structure in the ant brain.

Eberhard Bodenschatz gave a lively PKS colloquium talk on Monday afternoon, speaking about cilia-generated fluid flow in the brain. Surprisingly, these flows reverse direction depending on the signaling state of the brain.

The majority of speakers followed our suggestion to start their talk with a brief overview of their field and a short introduction of the relevant general concepts. This allowed the highly interdisciplinary audience to connect to the work of the other disciplines and revealed the commonalities between biological and robotic navigation.

A number of theoretical talks e.g. by Nihat Ay and Peter Thomas showed how general questions of minimal information processing capacity and trade-off choices for optimal navigation can be approached by formal methods. This approach is very important for the field as it allows to

distill generic principles from specific systems, yet the formal language of presentation can sometimes present a barrier for efficient communication. In this respect, it was very useful that the speakers illustrated the mathematical theorems presented by specific applications, allowing for example experimental physicists and biologists to connect to this theoretical research. On the other hand, several theoreticians emphasized in discussions how the talks by biologists sparked new ideas for their theoretical work. This positive experience highlights how biological systems can inspire the advancement of theoretical concepts.

As a novel element of the workshop, targeted at young scientists, we included a "poster flash-mob" into the workshop. Thus, in addition to the poster session on Monday evening, we

scheduled an extra session, where each poster presenter had 60 seconds to present his project in 1

or 2 slides. This format also emphasized the poster presentation as integral part of the workshop, as well as allowed the participants to directly approach the posters of maximal interest to them during the poster session. For the junior participant among the poster presenters, this "poster flash-mob" presented an opportunity to be on stage, even if only briefly, and to train their oral presentation skills.

The scientific results of the conference in the broader sense include a higher awareness of similar concepts concerning navigation strategies both in the field of biological and robotic navigation, and to foster new theory-experiment collaborations. Thereby, the workshop contributed to better connect said communities and to highlight the emerging field of bio-inspired robotics. Conversely, engineering concepts can prove useful to describe key principles of biological navigation. Information-theoretic concepts provide a unifying theme that connects both fields. Apart of giving a broad overview over various navigation strategies, the conference also accelerated the development of the field and was conducted in a highly inspiring atmosphere.

Several speakers and participants expressed their gratitude for the throughout high quality of the presentations, the broad range of topics brought together by a unifying theme, as well as the relaxed atmosphere during scientific discussions and poster sessions. We would like to add that MPIPKS and the workshop administrator Mandy Lochar excellently handled the organizational and other administrative formalities of the workshop.