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Takeshi Kano

Associate Professor

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Email
tkano[at]riec.tohoku.ac.jp

## Research Topics:

Our research group aims to understand mechanisms underlying collective behavior in multi-body systems such as traffic flow and flocking of animals and to develop control schemes for such systems. In multi-body systems, non-trivial collective behaviors emerge from local interaction among individuals. We seek for the core principle underlying collective behaviors by constructing a simple mathematical model, and then develop “reasonable” control schemes on this basis.

#### Mathematical modeling of animal locomotion

Animals exhibit astoundingly adaptive, robust, and versatile locomotion in response to the environment. My goal is to clarify the essential mechanisms of animal locomotion via mathematical modeling by focusing on decentralized control, in which non-trivial behavior emerges from the coordination of simple individual components. My research topics include the locomotion of snakes, ophiuroids (brittle star), earthworms, centipedes etc.

Representative papers: T. Sato, T. Kano, and A. Ishiguro, “On the Applicability of the Decentralized Control Mechanism Extracted from True Slime Mold --A Robotic Case Study with a Serpentine Robot--”, Bioinsp. Biomim. 6, 026006 (2011)
W. Watanabe, T. Kano, S. Suzuki, and A. Ishiguro, “A Decentralised Control Scheme for Orchestrating Versatile Arm Movements in Ophiuroid Omnidirectional Locomotion”, Journal of the Royal Society Interface 9, pp. 102-109 (2012)
T. Kano, S. Suzuki, W. Watanabe, and A. Ishiguro, “Ophiuroid robot that self-organizes periodic and non-periodic arm movements”, Bioinsp. Biomim., 7, 034001 (2012)
T. Kano, T. Sato, R. Kobayashi, and A. Ishiguro, “Local reflexive mechanisms essential for snakes' scaffold-based locomotion”, Bioinsp. Biomim., 7, 046008 (2012)
T. Kano, Y. Watanabe, and A. Ishiguro, “Towards realization of multi-terrestrial locomotion: decentralized control of sheet-like robot based on scaffold-exploitation mechanism”, Bioinsp. Biomim., 7, 046012 (2012)
D. Owaki, T. Kano, K. Nagasawa, A. Tero, and A. Ishiguro, “Simple robot suggests physical interlimb communication is essential for quadruped walking”, J. Roy. Soc. Int, 10(78), 20120669 (2013)

#### Decentralized control of traffic signals

Although various control schemes of traffic signals have been developed, adaptation to unpredictable changes in the amount of traffic still poses a challenge. To tackle this problem, I proposed an autonomous decentralized control scheme of traffic signals on the basis of physics considerations.

Representative paper T. Kano, Y. Sugiyama, A. Ishiguro, Autonomous decentralized control of traffic signals that can adapt to changes in traffic, Collective Dynamics, vol. 1, A5, pp. 1-18 2016.

#### A Minimal Model of Collective Behaviour Based on Non-reciprocal Interactions

The collective behaviour of individuals is widely observed in many natural and social systems. In these systems, Newton's third law, or the law of action--reaction, is often violated. Hence, interaction between individuals is often non-reciprocal. In this study, as the first step towards elucidating the essential mechanism of the aforementioned systems, a minimal model of collective behaviour based on non-reciprocal interactions is proposed by drawing inspiration from friendship formation in human society.

In this model, particles, each of which represents a person in a community, exist on a two-dimensional plane, and the position of the $i$th particle ($i=1,2,\cdot\cdot\cdot, N$) is denoted by $\mathbf{r}_i$. The time evolution of $\mathbf{r}_i$ is given by

$$\dot{\mathbf{r}}_i=\sum_{j\neq i}(k_{ij}|\mathbf{R}_{ij}|^{-1}-|\mathbf{R}_{ij}|^{-2})\hat{\mathbf{R}}_{ij} \tag{1}$$

where $\mathbf{R}_{ij}=\mathbf{r}_j-\mathbf{r}_i$, $\hat{\mathbf{R}}_{ij}=\mathbf{R}_{ij}/|\mathbf{R}_{ij}|$, and $k_{ij}$ denotes a constant that represents "to what extent person $i$ prefers person $j$.” The key here is that $k_{ij}$ is not necessarily equal to $k_{ji}$,$i.e.$, the interaction can be non-reciprocal. Thus, Eq. (1) is a non-equilibrium open system in which both energy and momentum are non-conservative.

It is demonstrated via simulations that various patterns emerge by changing the parameters (see http://www.riec.tohoku.ac.jp/~tkano/movie.mp4).

Representative paper

T. Kano, K. Osuka, T. Kawakatsu, N. Matsui and A. Ishiguro, A Minimal Model of Collective Behaviour Based on Non-reciprocal Interactions, Proc. of ECAL 2017 (accepted).

## Previous research topics:

#### Control of coupled-oscillator systems based on multi-linear feedback

Methods to control the dynamics of coupled oscillators have been developed owing to various medical and technological demands. In this study, we develop a method to control coupled oscillators in which the coupling function expressed in a phase model is regulated by the multilinear feedback. The present method has wide applicability because we do not need to measure an individual output from each oscillator, but only measure the sum of the outputs from all the oscillators. Moreover, it allows us to easily control the coupling function up to higher harmonics. The validity of the present method is confirmed through a simulation.

Representative papers:
T. Kano and S. Kinoshita, “Method to control the coupling function using multilinear feedback”, Phys. Rev. E 78(5), 056210 (2008)
T. Kano and S. Kinoshita, “Control of individual phase relationship between coupled oscillators using multilinear feedback”, Phys. Rev. E 81(2), 026206 (2010))

#### Density oscillator (or Saline oscillator)

The density oscillator is a simple system that exhibits self-sustained oscillation. It alternately exhibits up- and down-flow through a pipe which connects two containers filled with fluids of different densities. However, the mechanism of the flow reversal has not yet been fully understood. From the detailed measurements, we have found that flow reversal begins with an intrusion of fluid, which is followed by rapid growth. This process is definitely sensitive to the viscosities of the fluids, and as a consequence, the critical heights leading to flow reversal are clearly viscosity-dependent. These experimental results are explained by a simple model, derived by considering forces acting on a unit volume element located at the tip of the intrusion. Using this model, we can successfully explain the mechanism of flow reversal, which is the most essential process in a density oscillator.

Representative papers:
T. Kano and S. Kinoshita, “Viscosity-dependent flow reversal in a density oscillator”, Phys. Rev. E 76(4), 046208 (2007) T. Kano and S. Kinoshita, “Modeling of a density oscillator”, Phys. Rev. E 80(4), 046217 (2009) Shuichi Kinosita, Pattern Formation and Oscillatory Phenomena, Chapter 4

## Short Biography

I received an M.D. degree from Hokkaido University, Japan in March 2002. I received Ph. D. degree from Osaka University in March 2008. From April 2008 to July 2009, I was a postdoctoral researcher in Graduate School of Frontier Biosciences, Osaka University. From August 2009 to March 2011, I was an assistant professor of Tohoku University (Graduate School of Medicine). Since April 2011, I have been an assistant professor of the Research Institute of Electrical Communication, Tohoku University. Since October 2016, I have been an associate professor of the Research Institute of Electrical Communication, Tohoku University. I received several awards such as "2011 IEEE/RSJ International Conference on Intelligent Robots and Systems NTF Award Finalist for Entertainment Robots and Systems."