Published papers

We investigated agent-based model simulations that mimic an ant transportation system to analyze the cooperative perception and communication in the system. On a trail, ants use cooperative perception through chemotaxis to maintain a constant average velocity irrespective of their density, thereby avoiding traffic jams. Using model simulations and approximate mathematical representations, we analyzed various aspects of the communication system and their effects on cooperative perception in ant traffic. Based on the analysis, insights about the cooperative perception of ants which facilitate decentralized self-organization is presented. We also present values of communication-parameters in ant traffic, where the system conveys traffic conditions to individual ants, which ants use to self-organize and avoid traffic-jams. The mathematical analysis also verifies our findings and provides a better understanding of various model parameters leading to model improvements.

In this paper, we present an analysis of microscopic behaviors of ants to understand ant interactions that lead to jam-free ant traffic. For the analysis here, we use an agent-based model of ant traffic and mathematical analysis of key scenarios on the ant trail to understand relations between ants' environment and the interactions of ants with it. Our analysis indicates that ants increase their velocity for decreasing headway, which leads to a peculiar jam absorption mechanism. We also show that ants on trail collect information about flow in the recent past, which allows them to make informed decisions about their travel. Based on our observation, we propose that mimicking an ant communication system could help individuals in man-made transportation systems to make better decisions for higher efficiency, which could improve the efficiency of overall system.

In this paper, an agent-based model of ant traffic on a unidirectional single-lane ant trail is presented to provide better understanding of the jam-free traffic of an ant colony. On a trail, the average velocity of ants remains approximately constant irrespective of density, thereby avoiding jamming. Assuming chemotaxis, we analyze platoon-related scenarios to assess the marching-platoon hypothesis, which claims that ants on a trail form a single platoon in which they march synchronously, thereby reducing hindrances due to increasing density. Contrary to that hypothesis, our findings show that ants on a trail do not march synchronously and do experience stop-and-go motion. However, more interestingly, our study also indicates that the ants' chemotaxis behavior leads to a peculiar jam absorption mechanism, which helps to maintain free flow on a trail and avoids jamming. Again, contrary to the marching-platoon hypothesis, our findings also indicate that, rather than assisting traffic flow, forming a single cluster actually triggers jamming.

Human-machine interface (HMI) is an essential element of a conditional automated driving, which enables interaction between a driver and an automated driving system (ADS). This paper presents an approach to facilitate the design and verification of HMIs for transition of the vehicle control between the ADS and the driver in the context of the overall transportation systems. In this approach, a functional flow of an HMI is defined in the system model described using system modeling language (SysML). A visual display of HMI is designed and repeatedly verified using a driving simulator built by using the test case that utilizes the functional flow of HMI.

Navigation systems for motorcyclists are gaining attention using state-of-the-art technologies. While it is expected to provide benefits to riders similar to the technologies used for automobiles, the effectiveness of motorcycle head-up and head-mounted displays is not yet well understood. Therefore, this paper presents a human-centered design approach using a prototype of a motorcycle head-up display and an immersive virtual reality simulator. For validation, the motorcycle head-up display was equipped on a commercial motorcycle and tests were conducted in the real-world environment.

This paper introduces the motorcycle head-up display design of presenting information for navigation system. In particular, a human-centered design approach was adopted to design as a human-machine interface. Therefore, a motorcycle head-up display prototype was developed to perform tests to design information presentation for navigation system. Virtual reality environment was utilized as a test environment, with an operational motorcycle simulator equipped with a head-up display. For experimental subjects, motorcycle riders with license participated riding the operational simulator. The experimental results answered questions of presenting information design using head-up display for motorcycle.

Using an agent-based traffic models, we analyze the manner in which the number of platoons within a traffic system is correlated with the appearance of traffic jams. Two definitions of a platoon are proposed and verified using agent-based simulations to find the one that provides the most realistic representation of traffic behavior in a stochastic model. We observe that traffic jams are closely related to the convergence of multiple platoons into a single platoon containing all the agents in the model. We also observed that at high-density, traffic system maintains a metastable state when it has multiple platoons in it. A traffic jam occurs when these multiple platoons are merged into a single platoon, which is equivalent to the concept of an infinite cluster in percolation theory.

This paper introduces a project activity to design and verify human-machine interface (HMI) to safely realize the driving delegation between the driver and the automated driving system (ADS) in a transportation system, based on analysis of system of systems operational design domain where the constituent systems interact, including the vehicle with ADS, the ego vehicle driver, and external systems, such as surrounding mobilities, information communication systems, and traffic infrastructure systems. The system model of ADS designed is utilized to build a driving simulator to be used for HMI verification.

Causes and countermeasures for various kinds of hydraulic system failures in construction machinery generated by biodegradable hydraulic oil (bio-oil) are discussed. Previous component analytical methods can prevent all kinds of failures except hydraulic system malfunction, which requires a holistic approach for analysis. Using the Systems Modeling Language (SysML), the cause of malfunctions can be understood, and the most effective countermeasure can be obtained. Integration of a component analysis method and a holistic analysis method for system development is proposed.

自動二輪車のマルチボディダイナミクス解析を行うとともに，実車走行に合致する走行シミュレーションを行っている．タイヤ断面形状を考慮することで過渡応答が実車と整合性のある結果となること，タイヤの摩擦を考慮したレーンチェンジ走行を行い，タイヤに働く力と摩擦円との関係を明らかにしている．

車両用アクティブサスペンションにおいて，サスペンションばねのストロークエンドで衝撃的な応答が発生する問題に対処するため，ストロークエンドに到達する前からアクチュエータがそれを抑制するための力を発生させつつ，衝撃的な応答を抑制するスライディングモード制御系設計を施している．１／４アクティブサスペンション実験装置を用いて，提案する制御手法の有効性を検証している．

２物体間の衝突において，２物体間に挿入したアクチュエータによる能動的なフィードバック制御を行っている．衝撃を与えられる物体の弾塑性変形に応じた制御器のスケジューリングを施し，固定制御器の単なる切替制御の場合よりも短い時間内に大きな塑性変形率を得られることを示している．終端時間を長くすることにより，塑性変形率を増大できることはこれまでに示されてきたが，ゲインスケジュールド制御により，優れた特性を得ている．