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改良型前進後退スムーザを用いた飛行中の航空機重量のセンサフュージョンによる推定

石川敦也，成岡優，二宮哲次郎，足立修一

日本航空宇宙学会論文集 70 （ 2 ） 58 - 66 2022年04月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り

Spatio-temporal path planning for lunar polar exploration with robustness against schedule delay

Inoue H., Adachi S.

Transactions of the Japan Society for Aeronautical and Space Sciences （Transactions of the Japan Society for Aeronautical and Space Sciences） 64 （ 6 ） 304 - 311 2021年

ISSN 05493811

This paper presents a method to obtain a robust optimal path in an environment with time-varying safety features, such as in the lunar polar region. In designing the path for planetary exploration rovers, we must consider various safety conditions, such as terrain hazards, illumination, and communication visibility to the Earth. Some of the safety features are time-varying, and the optimal path should be searched for both the spatial direction and the temporal direction. In addition, there is no guarantee that all of the sequences will be successfully executed on time due to misoperation, failures, or trouble. Therefore, a path that is robust against the delay must be planned so as to guarantee safety even when behind schedule. The authors propose an algorithm called “Robust Spatio-Temporal Path Planner for the Planetary Rover (ROBUST-STP3R)” to obtain a path that is robust against schedule delay in a time-varying environment. This method defines a cost function that consists of the distance as well as the region type cost. To add robustness against schedule delays, the authors consider a weighted summation of the time-varying region type cost with regard to the temporal direction. The effectiveness of the proposed method is demonstrated through use in a simulated lunar polar exploration exercise.

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Resource and network management framework for a large-scale satellite communications system

Abe Y., Ogura M., Tsuji H., Miura A., Adachi S.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences （IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences） E103-A （ 2 ） 492 - 501 2020年02月

共著, ISSN 09168508

Satellite communications (SATCOM) systems play important roles in wireless communication systems. In the future, they will be required to accommodate rapidly increasing communication requests from various types of users. Therefore, we propose a framework for efficient resource management in large-scale SATCOMsystems that integrate multiple satellites. Such systems contain hundreds of thousands of communication satellites, user terminals, and gateway stations; thus, our proposed framework enables simpler and more reliable communication between users and satellites. To manage and control this system efficiently, we formulate an optimization problem that designs the network structure and allocates communication resources for a large-scale SATCOM system. In this mixed integer programming problem, we allow the cost function to be a combination of various factors so that SATCOM operators can design the network according to their individual management strategies. These factors include the total allocated bandwidth to users, the number of satellites and gateway stations to be used, and the number of total satellite handovers. Our numerical simulations show that the proposed management strategy outperforms a conventional strategy in which a user can connect to only one specific satellite determined in advance. Furthermore, we determine the effect of the number of satellites in the system on overall system performance.

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μ-マルコフモデルを用いた自動車用二次電池の内部インピーダンスの推定

佐々木理沙子，川口貴弘，丸田一郎，足立修一，片芝惇平，長村謙介

計測自動制御学会論文集 56 （ 2 ） 67 - 69 2020年02月

研究論文（学術雑誌）, 共著

ベクトル型可変忘却要素付き逐次最小二乗法を用いた非定常雑音下における原子時計の内部状態推定

馬渕俊一郎，平野将人，足立修一，井戸哲也，花土ゆう子

計測自動制御学会論文集 56 （ 2 ） 45 - 50 2020年02月

研究論文（学術雑誌）, 共著

Absum: Simple regularization method for reducing structural sensitivity of convolutional neural networks

Kanai S., Ida Y., Fujiwara Y., Yamada M., Adachi S.

AAAI 2020 - 34th AAAI Conference on Artificial Intelligence （AAAI 2020 - 34th AAAI Conference on Artificial Intelligence） 4394 - 4403 2020年

We propose Absum, which is a regularization method for improving adversarial robustness of convolutional neural networks (CNNs). Although CNNs can accurately recognize images, recent studies have shown that the convolution operations in CNNs commonly have structural sensitivity to specific noise composed of Fourier basis functions. By exploiting this sensitivity, they proposed a simple black-box adversarial attack: Single Fourier attack. To reduce structural sensitivity, we can use regularization of convolution filter weights since the sensitivity of linear transform can be assessed by the norm of the weights. However, standard regularization methods can prevent minimization of the loss function because they impose a tight constraint for obtaining high robustness. To solve this problem, Absum imposes a loose constraint; it penalizes the absolute values of the summation of the parameters in the convolution layers. Absum can improve robustness against single Fourier attack while being as simple and efficient as standard regularization methods (e.g., weight decay and L1 regularization). Our experiments demonstrate that Absum improves robustness against single Fourier attack more than standard regularization methods. Furthermore, we reveal that robust CNNs with Absum are more robust against transferred attacks due to decreasing the common sensitivity and against high-frequency noise than standard regularization methods. We also reveal that Absum can improve robustness against gradient-based attacks (projected gradient descent) when used with adversarial training.

Resource and network management for satellite communications systems: A chance-constrained approach

Abe Y., Ogura M., Tsuji H., Miura A., Adachi S.

IFAC-PapersOnLine （IFAC-PapersOnLine） 53 （ 2 ） 3304 - 3309 2020年

In this paper, we propose an optimization framework for the resource and network management in large-scale satellite communications (SATCOM) systems with stochastic and time-varying communication requests. Because further expansions of SATCOM systems are expected in the near future, it is of practical importance to develop management methodologies for efficiently and robustly operating large-scale SATCOM systems. To address this problem, in this paper, we formulate a SATCOM network optimization problem within the framework of the chance-constrained model predictive control. In this problem, we require that a joint chance constraint on the bandwidth loss rate is satisfied with a user-specified performance and probability. Because the joint chance constraint is nonlinear in design variables, we relax the constraint to a linear deterministic one for reformulating the original problem into a relaxed deterministic problem. We numerically verify that the proposed method outperforms a baseline methodology and therefore allows us to efficiently manage large-scale SATCOM systems.

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Path planning for lunar polar exploration mission using linear temporal logic

Kikuchi Y., Adachi S., Inoue H., Hashimoto K.

AIAA Scitech 2020 Forum （AIAA Scitech 2020 Forum） 1 PartF 1 - 9 2020年

For path planning of planetary exploration rover travelling toward several points of interest, it is necessary to optimize the order of the exploratory points, and consider various safety features, such as terrain hazards, illumination condition, and communication visibility to the earth. This paper presents a method to obtain optimal path in consideration of the remaining charge of the rover, according to the prospected mission in an environment with time-varying safety features, such as in lunar polar region. We demonstrated the effectiveness of the proposed method in numerical simulations.

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Calibration Method for Array Antenna Considering Mutual Coupling of Elements in Satellite Communications

Tsuji H., Abe Y., Kondo T., Kikuchi Y., Adachi S.

International Symposium on Wireless Personal Multimedia Communications, WPMC （International Symposium on Wireless Personal Multimedia Communications, WPMC） 2019-November 2019年11月

ISSN 13476890

This paper proposes a calibration method for array antennas which includes the mutual coupling between antenna elements. Conventional methods such as the rotating element electric field vector (REV) method for the elements of array antennas do not account for the mutual coupling between elements. When an antenna calibration is not performed adequately, the radiation intensity of the radio waves in the undesired direction increases, causing interference with other satellites which are not intended. In order to overcome this drawback, a model of an array antenna including a coupling between antenna elements is constructed. Using this model, the estimation problem of the effect of the mutual coupling is formulated as formulation problem. Finally, a calibration method based on the solution of the optimization problem is derived.

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State feedback synthesis for discrete-time linear systems with stochastic parameters guaranteeing deterministic H<inf>2</inf> performance and stochastic stability

Niwa K., Hattaha K., Sato M., Adachi S.

IFAC-PapersOnLine （IFAC-PapersOnLine） 52 （ 16 ） 664 - 669 2019年09月

In this paper, we propose a design method of state feedback controllers for discrete-time linear systems whose state-space matrices contain stochastic parameters. For such systems, if the parameters fluctuate according to the normal distribution, it is impossible to strictly guarantee the “conventional deterministic control performance” due to the unlimited parameter variations. Then, in our problem setup, we consider incorporating the “stochastic stability” into the conventional deterministic H2 performance. We derive a design condition on state feedback controllers which achieve deterministic H2 performance and stochastic stability simultaneously in terms of linear matrix inequalities (LMIs) via extended LMI. The effectiveness of the proposed method is illustrated through a numerical example.

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Gated recurrent unit の局所安定化による勾配爆発の抑制

金井関利，藤原靖宏，岩村相哲，足立修一

電子情報通信学会和文論文誌 D J102-D （ 8 ） 530 - 541 2019年08月

研究論文（学術雑誌）, 共著

出力追従制御を応用したトランスオーラル再生制御器設計における制約緩和

松井健太郎，伊藤敦郎，森翔平，井上正樹，足立修一

日本音響学会誌 75 （ 7 ） 374 - 383 2019年07月

研究論文（学術雑誌）, 共著

不確かさをもつターボチャージシステムの可到達解析と安全性検証法

八田羽謙一，橋本和宗，井上正樹，足立修一，上野将樹，堤優二郎，山田雄輝，豊嶋弘和

自動車技術会論文集 50 （ 3 ） 957 - 962 2019年05月

研究論文（学術雑誌）, 共著

State estimation for multiple clocks under anomalies using ℓ<inf>1</inf>-norm optimization

Hirano M., Hashimoto K., Nakagawa F., Ido T., Hanado Y., Adachi S.

Metrologia （Metrologia） 56 （ 2 ） 2019年03月

ISSN 00261394

© 2019 BIPM & IOP Publishing Ltd. We investigate an estimation strategy for multiple clock systems, which is in particular resilient against clock anomalies. The clock anomalies, including frequency or phase jumps, can potentially degrade the estimation performance for multiple clock systems. While the conventional Kalman filter is known as one of the powerful methods for the estimation problem of multiple clock systems, we will show that it is vulnerable to the effects of clock anomalies. In this paper, we overcome this issue by employing an alternative approach to the Kalman filter, which is based on solving the ℓ1-norm optimization problem. The estimation method employs a multiple clock model that includes only phase states. Nevertheless, the approach is shown to have more resilience against clock anomalies than the Kalman filter, because the deviation of the state from the apriori estimate is evaluated based on the ℓ1-norm instead of the ℓ2-norm. Moreover, the approach is shown to be competitive with many reset algorithms, since it does neighter require special stability assumptions about the reference clock, nor require any threshold for detecting the anomalies. The usefulness of the proposed method is validated through several numerical examples using actual clock data.

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State-of-Charge Estimation of Rechargeable Batteries guaranteed Finite-Time Estimation Error Convergence

Hattaha K., Ono T., Sasaki R., Osamura K., Adachi S.

Proceedings of 2019 SICE International Symposium on Control Systems, SICE ISCS 2019 （Proceedings of 2019 SICE International Symposium on Control Systems, SICE ISCS 2019） 72 - 77 2019年03月

ISSN 9784907764623

© 2019 The Society of Instrument and Control Engineers - SICE. We propose a model-based state-of-charge (SOC) estimation method for rechargeable batteries which guarantees finite-time estimation error convergence. One of the most common approaches for the SOC estimation based on equivalent circuit model is to utilize the Kalman filter. The method has an asymptotic convergence property. From the practical standpoint, however, an estimation method that guarantees a finite-time estimation error convergence is desired. To this end, we employ the impulsive observer which achieves the finite-time estimation error convergence with the exact model. Furthermore, we analize the bounds of estimation errors in the case that the model used in the impulsive observer has errors. Finally, the effectiveness of the proposed method is illustrated through numerical experiments.

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Energy-aware networked control systems under temporal logic specifications

Hashimoto K., Adachi S., Dimarogonas D.

Proceedings of the IEEE Conference on Decision and Control （Proceedings of the IEEE Conference on Decision and Control） 2018-December 132 - 139 2019年01月

ISSN 9781538613955

© 2018 IEEE. In recent years, event and self-triggered control have been proposed as energy-aware control strategies to expand the life-time of battery powered devices in Networked Control Systems (NCSs). In contrast to the previous works in which their control objective is to achieve stability, this paper presents a novel energy-aware control scheme for achieving high level specifications, or more specifically, temporal logic specifications. Inspired by the standard hierarchical strategy that has been proposed in the field of formal control synthesis paradigm, we propose a new abstraction procedure for jointly synthesizing control and communication strategies, such that the communication reduction in NCSs and the satisfaction of the temporal logic specifications are guaranteed. The benefits of the proposal are illustrated through a numerical example.

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Calibration method for array antenna considering mutual coupling in mobile satellite communications

Tsuji H., Abe Y., Kondo T., Kikuchi Y., Adachi S.

IET Conference Publications （IET Conference Publications） 2019 （ CP774 ） 2019年

In this chapter, we propose a calibration method for an array antenna, which includes electromagnetic coupling between antenna elements. Conventional methods such as the rotating element electric field vector (REV) method for elements of an array antenna do not take into account the electromagnetic coupling between elements. If the antenna calibration is not properly performed, the radiation pattern of the radio waves in the undesired directions will increase and interfere with the other satellites that are not intended. To overcome this drawback, a model of an array antenna including the mutual coupling between antenna elements has been constructed. Using this model, the estimation problem of the effect of the mutual coupling is formulated as a formulation problem. Finally, a calibration method based on the solution of the optimization problem is derived and shows the effectiveness of the method through some numerical examples.

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Frequency resource management based on model predictive control for satellite communications system

Abe Y., Tsuji H., Miura A., Adachi S.

研究論文（学術雑誌）, 共著, 査読有り, ISSN 09168508

Copyright © 2018 The Institute of Electronics, Information and Communication Engineers. We propose an approach to allocate bandwidth for a satellite communications (SATCOM) system that includes the recent highthroughput satellite (HTS) with frequency flexibility. To efficiently operate the system, we manage the limited bandwidth resources available for SATCOM by employing a control method that allows the allocated bandwidths to exceed the communication demand of user terminals per HTS beam. To this end, we consider bandwidth allocation for SATCOM as an optimal control problem. Then, assuming that the model of communication requests is available, we propose an optimal control method by combining model predictive control and sparse optimization. The resulting control method enables the efficient use of the limited bandwidth and reduces the bandwidth loss and number of control actions for the HTS compared to a setup with conventional frequency allocation and no frequency flexibility. Furthermore, the proposed method allows to allocate bandwidth depending on various control objectives and beam priorities by tuning the corresponding weighting matrices. These findings were verified through numerical simulations by using a simple time variation model of the communication requests and predicted aircraft communication demand obtained from the analysis of actual flight tracking data.

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Frequency Resource Allocation for Satellite Communications System Based on Model Predictive Control and Its Application to Frequency Bandwidth Allocation for Aircraft

Abe Y., Tsuji H., Miura A., Adachi S.

2018 IEEE Conference on Control Technology and Applications, CCTA 2018 （2018 IEEE Conference on Control Technology and Applications, CCTA 2018） 165 - 170 2018年10月

ISSN 9781538676981

© 2018 IEEE. In this paper, we propose a frequency bandwidth allocation method for satellite communications (SATCOM) based on the Model Predictive Control (MPC) and a sparse optimization method. To utilize limited frequency bandwidth resources of SATCOM efficiently, control strategies for SATCOM system are studied. We treat the frequency bandwidth allocation problem for SATCOM as an optimal control problem. Then, based on the assumption that a time variation model of communication requests is obtained, we propose an optimal control method based on the MPC and the sparse optimization. By utilizing the proposed method, the limited frequency bandwidth is utilized efficiently. We verify the effectiveness of the proposed method in a numerical simulation by using actual data of aircraft.

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Observability Analysis for Simultaneous State and Physical Parameters Estimation of Rechargeable Batteries

Sasaki R., Kawaguchi T., Hattaha K., Inoue M., Adachi S.

2018 IEEE Conference on Control Technology and Applications, CCTA 2018 （2018 IEEE Conference on Control Technology and Applications, CCTA 2018） 1409 - 1414 2018年10月

ISSN 9781538676981

© 2018 IEEE. In this paper, we address simultaneous estimation problems (SEPs) of state and physical parameters of rechargeable batteries. In general, the problems are transformed to state estimation of an augmented system whose state includes the parameters of the original system. Then, the SEPs are commonly solved by estimating the state of the augmented system. As a drawback of the solution, the simultaneous estimation fails for some types of the input currents. In this paper, we attempt to find input current conditions such that the SEPs are theoretically solved, through observability analysis of the augmented system.

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