担当区分：最終著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>The effectiveness of observer-based controllers using Luenberger observers is well recognized. As the estimated states can be used for possible fault detection, health monitoring, etc., the estimation of plant states is useful. Therefore, a conversion method of transforming <i>a priori</i> designed controllers to observer-based controllers has been proposed. This conversion method is attractive, but it is applicable only for the case that LTI plant systems are controlled by LTI controllers. To enhance the applicability, observer-structured controllers with a structural similarity to the Luenberger observer-based controllers have been proposed, and the conversion method to observer-structured controllers using state-transformation matrices has also been proposed. This method uses mathematical models instead of operational data, thus, observer-structured controllers inevitably suffer from plant state estimation degradation due to unforeseen uncertainties and disturbances in real environments. On this issue, under the condition that a few sets of the plant and controller states in real operating environments are available, a method for obtaining state-transformation matrices using the obtained operational data has been proposed with an illustrative example. However, there is a concern that the numerical complexity in designing state-transformation matrices increases as the amount of the data grows. To solve this concern, this paper proposes a remedy of numerical complexity reduction in obtaining state-transformation matrices using operational data with downsampling approach. The usefulness and the validity of our method are confirmed through a numerical example.</p>

DOI： 10.9746/sicetr.62.269

CiNii Research

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This note tackles visual-feedback controller design for a cart-driven inverted pendulum using non-calibrated images taken through a fisheye lens. The images have distortion, which can be modeled as an uncertainty in the output matrix for the measurement signals, due to the use of hemispherical lenses. This problem can be reduced to robust controller design for LTI parametrically dependent systems which belong to a subclass of Linear Parameter-Varying (LPV) systems. This research topic, i.e. robust controller design, is slightly obsolete; however, it is still a challenging problem since the well-established change-of-variables procedure for parametrically dependent plant systems produces not constant controllers but parametrically dependent controllers. On this issue, we first introduce a fictitious parameter vector in the change-of-variables procedure to obtain constant state-space matrices of the to-be-designed controllers in exchange for consequently introduced bilinear terms of decision matrices, and then apply overbounding approach based on Elimination lemma with an auxiliary decision matrix introduced for the bilinear terms to derive our proposed method. The method is still formulated in terms of bilinear matrix inequality, but has no structural constraints for the original decision matrices in the initial feasible solution search. We apply the proposed method to the stabilization problem of the cart-driven inverted pendulum. We successfully design a robust visual-feedback stabilizing controller, and lab-level experiments confirm that our controller stabilizes the system without any calibrations for the distorted images.</p>

DOI： 10.9746/sicetr.62.121

CiNii Research

その他リンク： http://id.ndl.go.jp/bib/034638886

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

PID-based Stability/Control Augmentation System (S/CAS) is widely used for controlling aircraft, and, in general, it does not have any other functions apart from closed-loop stability and ensured maneuverability. On this issue, observer-structured controllers, which are converted from a priori designed unstructured controllers into Luenberger observer-like structured controllers with plant state estimation ability, have been proposed via state transformation. However, the plant state estimation is inevitably degraded due to unforeseen uncertainties and disturbances in real environments as the transformation matrices are derived using mathematical plant models. To address this issue, we propose a conversion method with state transformation matrices calculated using the data obtained in a preliminary controller implementation phase under actual environments. Furthermore, a proposition to reduce the numerical complexity in calculating the state transformation matrices is also given.

DOI： 10.1016/j.ifacol.2025.11.244

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This note addresses the conversion problem of <i>a priori</i> designed unstructured controllers to <i>observer-structured controllers</i>. Observer-structured controllers have been proposed as a structural extension of Luenberger observer-based controllers to accommodate linear parametric plant systems with unspecified nominal state-space matrices, and the usefulness has been demonstrated in the literature. However, the conversion process in the literature uses only the mathematical models of the plant systems and the <i>a priori</i> designed unstructured controllers, which might degrade the plant state estimation performance of the converted observer-structured controllers due to the possibility of unexpected disturbances, unmodeled dynamics, etc. of the practical operating environment. Therefore, a conversion method which well reflects the practical operating environment has been desired. To this end, this note proposes a conversion method, which is based on the least square method, by using the data of the plant systems controlled by the <i>a priori</i> designed unstructured controllers under practical operating environment, and illustrates the effectiveness of our method.</p>

DOI： 10.5687/iscie.38.146

Kyutacar

CiNii Research

その他リンク： http://id.ndl.go.jp/bib/034203036

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This note shows robustness against so-called “matched uncertainty” of Linear Parameter-Varying (LPV) systems can be ensured by linear state-feedback controllers combined with internal saturation. It is well-known that Sliding Mode Control (SMC) has strong robustness against matched uncertainties, i.e. the uncertainties belonging to the image of the control input matrix. This property makes SMC useful in many practical application fields, e.g. Fault-Tolerant Control (FTC), Fault Detection and Identification (FDI), etc. However, this property is not unique to SMC, and this note shows that it also holds for a control scheme based on linear state-feedback controllers combined with internal saturation. For the implementation of SMC, modified signum functions, i.e. sigmoid-like functions with smoothing factors, are often used instead of ideal ones to avoid chattering. This note clarifies that the role of the smoothing factors in diagonalization SMC is characterized as the reciprocal of the gains for switching functions, and proves that linear state-feedback controllers combined with internal saturation have smaller boundary layers than diagonalization SMC with sigmoid-like functions.

DOI： 10.1016/j.ifacol.2025.10.128

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper addresses robust controller design for Linear Parameter-Varying (LPV) systems in which only the output matrix (i.e. C<inf>2</inf> matrix) is parametrically dependent. For this problem, the so-called “change-of-variables” procedure, which is well-established for full-order LTI/LPV controller design for LTI/LPV systems, is not applicable. This is because the direct application of the change-of-variables procedure to LPV systems produces parametrically dependent controllers, i.e. gain-scheduled controllers. To solve this issue, we introduce an artificial output matrix in our modified change-of-variables procedure and give a formulation for our problem in terms of Bilinear Matrix Inequality (BMI). We adopt overbounding approach proposed in literature to solve the BMI by considering that it imposes no structural constraints on the original decision matrices for finding the initial feasible solution. An application example to visual feedback controller design well illustrates the effectiveness of our proposed method.

DOI： 10.1016/j.ifacol.2025.10.122

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Finite-horizon performance analysis is addressed for time-varying uncertain linear systems. The results apply to state-space models with matrices rational in both time and a scalar uncertainty. Performance measures include finite-time stability and L<inf>2</inf> induced gain like criteria, which converge to standard stability and L<inf>2</inf> induced norm as the time horizon goes to infinity. Results are formalized in terms of linear matrix inequalities by applying the S-variable approach. Two improvements to this approach are proposed to reduce conservatism and deal with positive unbounded indeterminates such as time. A descriptor modeling framework and a lifting-based methodology are used to build tractable results aiming at decreasing conservatism.

DOI： 10.1016/j.ifacol.2025.10.107

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

In most cases, control systems are subject to uncertainties. Therefore, it is crucial to design robust controllers against such uncertainties. One representative approach for this purpose is gain-scheduled control. Gain-scheduled control is a powerful, robust control method that can be designed when uncertainties that are measurable online, known as scheduling parameters, exist. However, scheduling parameters are not always measurable online, so it is important to relax the condition of their availability. To address this, a method that estimates the scheduling parameter by a disturbance observer and the recursive least squares method was proposed. Nevertheless, a major drawback of the approach was that the estimate could converge to zero for some numerical examples. To overcome this drawback, this paper proposes a novel estimation method that combines a disturbance observer with an adaptive estimation mechanism. This paper also shows the effectiveness of the proposed method through a numerical example.

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper gives a comparative study of Sliding Mode Control (SMC) with smoothing factors and Linear State-Feedback Control (LSFC) with internal saturation for satellite attitude control. It is well-known that SMC has a strong robustness against so-called “matched uncertainty”, which is characterized as the uncertainties belonging to the image of the control input matrix of plant system. Thanks to this property, visual-feedback based satellite attitude control using SMC is discussed for Hayabusa2 in a flyby imaging mission near an asteroid “2001 CC21” on the way for its “Extended mission” to the asteroid “1998 KY26.” The feasibility study of capturing the asteroid image of “2001 CC21” using SMC with smoothing factors during the flyby has been conducted, and the usefulness of SMC with smoothing factors compared to PD (Proportional and Derivative) controller has been demonstrated. We show the result of applying LSFC combined with internal saturation to the same mission, i.e. capturing the asteroid image of “2001 CC21” during the flyby, and also point out issues for further control performance improvement.

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This article proposes a holistic actuator fault tolerant control (FTC) scheme and validates it using the Japan Aerospace Exploration Agency's Multi-Purpose Aviation Laboratory (MuPAL-α) Aircraft-in-the-Loop platform. The motivation for this work is to increase the technology readiness level associated with FTC technology, whilst improving the sustainability of future aircraft. The overall scheme uses bespoke sliding mode observers at a (local) individual actuator level to assess the health and the effectiveness level of each of the actuators. These estimates are aggregated and used in the control allocation mechanism to distribute a virtual control signal, designed using sliding mode control concepts, to the physical actuators. The overall closed-loop system stability is rigorously analyzed. The validation results show that the actuator effectiveness is well reconstructed and near nominal lateral-directional control performance is retained in the face of a class of actuator faults.

DOI： 10.1109/TAES.2025.3538823

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper proposes a design method of robust controllers for systems containing uncertainties in the measurement equation. For our specific problem of visual feedback control, the effects of image distortion are reflected as uncertainties represented in an affine manner. In our previous design method, it is implicitly assumed that the parameter, which is used for deriving the state-space matrices of the controller to be designed, is chosen as the nominal value of the uncertainty parameter. This assumption causes some conservatism. We thus propose a new design method by replacing the nominal value of the uncertainty parameter in our previous method as a newly introduced fictitious parameter whose value should be a priori set but can be chosen freely. A controller for a visual feedback system which allows measurement errors due to large lens distortion is designed by using the proposed method. The validity of our controller is confirmed by a lab-level experimental setup.

DOI： 10.1080/18824889.2025.2497612

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper proposes an $H_{\infty}$ controller design method for two-degree-of-freedom (2-DOF) control systems with lower sensitivity characteristics in the low-frequency range similar to that achieved by disturbance observers. The slopes of the magnitude plots of the sensitivity functions achieved by disturbance observers are $40[\text{dB} / \text{dec}]$, while the systems are servo systems for step signals. Previous research demonstrated that incorporating integral weighting for input disturbances could achieve such low-sensitivity characteristics. However, with that method, the dynamics of the plant affect the output sensitivity function in the evaluated transfer function. Therefore, it is difficult to shape the output sensitivity function precisely. This paper emphasizes the importance of directly shaping the output sensitivity functions and proposes to move the integral weight from the input side of the plant to the output side. This approach allows for precisely shaping sensitivity functions while maintaining servo characteristics. Numerical examples demonstrate the effectiveness of the proposed method.

DOI： 10.23919/SICEFES67750.2025.11236579

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper proposes an H<inf>∞</inf> controller design method for two-degree-of-freedom (2-DOF) control systems with lower sensitivity characteristics in the low-frequency range similar to that achieved by disturbance observers. The slopes of the magnitude plots of the sensitivity functions achieved by disturbance observers are 40 [dB/dec], while the systems are servo systems for step signals. Previous research demonstrated that incorporating integral weighting for input disturbances could achieve such low-sensitivity characteristics. However, with that method, the dynamics of the plant affect the output sensitivity function in the evaluated transfer function. Therefore, it is difficult to shape the output sensitivity function precisely. This paper emphasizes the importance of directly shaping the output sensitivity functions and proposes to move the integral weight from the input side of the plant to the output side. This approach allows for precisely shaping sensitivity functions while maintaining servo characteristics. Numerical examples demonstrate the effectiveness of the proposed method.

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper discusses fault-tolerant control using recursive Gaussian processes (RGP) and observer-structured robust output feedback controllers. The proposed method can detect variations in plant dynamics based on estimated plant state using RGP. The paper gives a design method for robust dynamic output feedback controllers based on generalized plants considering uncertainties due to some faults. When output feedback control is required, running RGP that use the plant state is complicated. In addition, the existence of the uncertainties makes conventional observers unreliable. These issues motivate us to adopt observer-structured controllers, which are obtained from a priori designed dynamic output feedback controllers through only appropriate state transformations without control performance degradation. Running this scheme online makes it possible to guarantee robust stability for plants after dynamics changes due to some faults. Two numerical examples of a web server model and an airplane model illustrate the effectiveness of the proposed method.

DOI： 10.1049/cth2.70058

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

In most cases, control systems are subject to uncertainties. Therefore, it is crucial to design robust controllers against such uncertainties. One representative approach for this purpose is gain-scheduled control. Gain-scheduled control is a powerful, robust control method that can be designed when uncertainties that are measurable online, known as scheduling parameters, exist. However, scheduling parameters are not always measurable online, so it is important to relax the condition of their availability. To address this, a method that estimates the scheduling parameter by a disturbance observer and the recursive least squares method was proposed. Nevertheless, a major drawback of the approach was that the estimate could converge to zero for some numerical examples. To overcome this drawback, this paper proposes a novel estimation method that combines a disturbance observer with an adaptive estimation mechanism. This paper also shows the effectiveness of the proposed method through a numerical example.

DOI： 10.23919/SICEFES67750.2025.11236598

Scopus

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This note proposes a design method of quasi Sliding Mode Control (SMC) for Linear Parameter-Varying (LPV) systems as the combination of Linear State-Feedback Control (LSFC) and additional internal saturation by extending an LSFC gain parametrization for LTI systems in the literature. A numerical example well illustrates the advantage of our controller.</p>

DOI： 10.9746/sicetr.61.405

CiNii Research

その他リンク： http://id.ndl.go.jp/bib/034329219

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper presents the design of a self-scheduled fault-tolerant controller for the lateral/directional motion of MuPAL- (Formula presented.) research aircraft using a polynomial-scheduled structured H (Formula presented.) control. The controller is designed to be tolerant against loss-of-efficiency faults in the aileron and rudder, but based on industrial best practices it is scheduled with respect to an overall fault level instead of with respect to the individual faults. The performance and robustness of the resulting controller is verified first using frequency and time domain analysis, and subsequently it is validated in the Aircraft-In-the-Loop configuration of MuPAL- (Formula presented.), where the real aircraft is operated in research Fly-By-Wire mode by the pilot on-ground while coupled to an emulation computer that simulates the aircraft flying motion. The results show good behavior of the controlled aircraft across the defined fault scenarios.

DOI： 10.1002/rnc.7088

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper proposes an H∞ controller design method which realizes a two-degree-of-freedom (2-DOF) control system with lower sensitivity characteristics in the low-frequency range. A control system with a disturbance observer is a 2-DOF control system that can achieve low sensitivity characteristics in the specific low-frequency range. However, the design of a controller with a disturbance observer structure is a non-convex optimization problem if it is considered as an observer gain design problem. In addition, it has not yet been revealed whether a 2-DOF control system with the low sensitivity characteristics of the disturbance observer can be achieved by the H∞ controller design. Therefore, this paper proposes a design method for H∞ controllers that achieves the low-sensitivity characteristics of a type 2 servo system while maintaining the type 1 servo characteristics without specifying the disturbance observer structure. Numerical examples demonstrate the effectiveness of the proposed method.

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This note addresses the robust visual-feedback controller design problem for a cart-driven pendulum using distorted images. This topic has already been addressed by several researchers; however, the adopted methods in the literature are conservative with respect to the freedom for designing controllers and/or the parameter-dependency of the Lyapunov functions. We therefore extend the design method using fictitious parameters and constant Lyapunov functions in the literature to the counterpart one using fictitious parameters and parametrically dependent Lyapunov functions. Thanks to the use of parametrically dependent Lyapunov functions, the proposed method is guaranteed to be no more conservative than the methods in the literature. We demonstrate the conservatism reduction of our proposed method compared to the method using fictitious parameters and constant Lyapunov functions for the design problem of robust visual-feedback controllers for the cart-driven pendulum. The design results as well as the experimental results are included to illustrate our contributions.

DOI： 10.1109/CCTA60707.2024.10666510

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper addresses the position control of a cart-driven inverted pendulum, whose position and angle are both calculated from the non-calibrated images taken through a fisheye lens, using a visual feedback controller. Fisheye lenses, which have the ability to obtain 180^ºwide or even wider view images, are advantageous to measurement compared to normal lenses; however, large distortion of the images cannot be avoided. In other words, fisheye lenses have a good potential as a measurement apparatus thanks to the wide view angles and the easy implementability as an add-on apparatus, it is necessary to overcome the drawback of the large image distortion to enhance the applicability. When fisheye lenses are used for controlling some systems, one of the possible solutions to overcome the drawback is to make the controllers robust against the image distortion. Along with this approach, we have already designed a visual stabilizing feedback controller for a cart-driven inverted pendulum and have confirmed its robustness against the large image distortion; however, cart position control has not yet been addressed. In this paper, we tackle the cart position control by designing a visual servo feedback controller within the framework of the conventional scaled-H∞ problem, examine control performance by experiments conducted in the laboratory, and confirm the usefulness of fisheye lenses.

DOI： 10.1109/ICARCV63323.2024.10821582

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This note shows two design examples of PID con-Trollers, whose state variables estimate the selected state vari-Ables of the controlled plant systems, for LTI Parametrically Dependent (LTIPD) systems. The authors have already proposed observer-structured controllers, whose structure is not the same as but is very similar to the well-established Luenberger observer-based controllers, and have also proposed a conversion method from a priori designed unstructured LTI or Linear Parameter-Varying (LPV) controllers to observer-structured LTI/LPV con-Trollers with the plant state estimation ability implemented. How-ever, the successful conversion has been reported only for full-order controllers. In this note, we show two examples, in which a priori designed LTI PID controllers are successfully converted to observer-structured PID controllers, and the designed observer-structured PID controllers well estimate the selected plant state variables in numerical simulations.

DOI： 10.1109/ICECCME62383.2024.10797124

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The purpose of the present research is to develop and to demonstrate the design architecture of the AFTS (Automatic Flight and Transition System) for "Lift/Cruise Thrust"type VTOL (Vertical Takeoff and Landing) aircraft such as tiltwing, tilt-propeller, tilt-duct aircraft, etc. VTOL aircraft of this type, characterized by propulsor installations that reorient the thrust relative to the aircraft, offer advantages of a wide flight envelope. However, flight and stability characteristics significantly change depending on airspeed and configurations such as wing tilt angles or propulsor orientations. These make it difficult to operate VTOL aircraft safely and the AFTS, which comprises both autopilot and auto-transition algorithm, should be developed to provide the safe and effective means to control the aircraft over its entire flight envelope. In this research, the autopilot was designed to provide control commands that change control strategies and gains according to the configurations. Additionally, the auto-transition algorithm, which should be coordinated with the autopilot, was designed to select and change configurations for accelerated and decelerated flight. The proposed AFTS was installed to a "Lift/Cruise Thrust"type, QTW (Quad Tilt Wing) VTOL UAS (Unmanned Aircraft System), and fully automated operation capability was demonstrated through flight test both in calm and windy conditions.

DOI： 10.2322/tjsass.67.285

Scopus

CiNii Research

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper proposes a method for estimating scheduling parameters using a disturbance observer. The input and output values of the scheduling parameters are estimated by a disturbance observer, and the scheduling parameters are estimated by calculating the ratio of these values. The effectiveness of the gain-scheduled control using the estimated values is verified by comparing the gain-scheduled control with actual scheduling parameters and the conventional robust control designed by the scaled H∞ control.

Scopus

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記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）

DOI： 10.11511/jacc.67.0_596

CiNii Research

記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11511/jacc.67.0_1663

CiNii Research

担当区分：最終著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11511/jacc.67.0_657

CiNii Research

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This article presents the structured H<inf>∞</inf> design and validation of two types of flight controller architectures: a passive fault-tolerant controller for the longitudinal motion and an active observer-based fault-tolerant controller for the lateral-directional motion. In the first, the controller follows the conventional Stability/Control Augmentation System (SCAS) structure, and its gains are obtained in continuous-time with the hinfstruct command by considering a set of elevator Loss-Of-Efficiency (LOE) faults. For the second, the conventional Luenberger observer-based controller structure is used, and the design aims to monitor the health of the aileron and rudder actuators in addition to provide active tolerance against LOE faults. Two different discrete-time designs are obtained for the latter, one focused on control performance optimization (using also the hinfstruct command), and the other on simultaneous control and observer performance optimization (using the systune command and under a slightly relaxed control performance constraint). For the two types of architectures, unmodeled dynamics are represented by uncertain bounded time delays modeled as pure delays or first-order Padé approximations. The resulting controllers are implemented on-board JAXA's research airplane MuPAL-α, and not only is their practicality demonstrated but also control performance is validated via Aircraft-In-the-Loop (AIL) testing under gust-free and realistic gusty conditions. This demonstration is at a Technological Readiness Level (TRL) of 7–8, resulting in a high-level of confidence in the validity of the proposed flight control structures.

DOI： 10.1016/j.isatra.2023.08.029

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記述言語：英語   掲載種別：研究論文（学術雑誌）

A linear parameter varying sliding mode fault reconstruction scheme is proposed. Compared with other conventional sliding mode observer designs, the estimate emerges quite naturally from the equations governing the sliding motion, and although the process may be viewed as a filtering of the discontinuous injection, there is no phase lag introduced in the process. A semi-analytic solution to the proposed linear parameter varying sliding mode observer is first discussed. This motivates the structure of the linear matrix inequality formulation which is proposed, and clarifies the class of systems to which the approach is applicable. The linear matrix inequality problem set up minimizes the induced (Figure presented.) gain between the fault estimate and external disturbances, whilst ensuring linear quadratic performance of the underpinning sliding motion. The proposed scheme has been validated using the Japan Aerospace Exploration Agency's Multi-Purpose Aviation Laboratory aircraft-in-the-loop platform to demonstrate the design efficacy.

DOI： 10.1002/rnc.6307

Scopus

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記述言語：英語   掲載種別：記事・総説・解説・論説等（学術雑誌）

<p>This paper describes the Industrial Benchmark jointly proposed by Airbus and Stellenbosch University for the 22nd IFAC World Congress, and supported by Kumamoto and Tohoku Universities as part of the World Congress Aerospace Technology Industry Group Organizers. The benchmark was used for an Aerospace competition, as one of the World Congress Technology competitions. This paper details the industrial context, describes the technical problem that was provided to be solved, and shows the significance of the problem from the perspective of the aerospace industry. Among all of the contributions that were received, five were selected based on the academic quality and on the industrial relevance and feasibility. A brief description of each selected paper is provided.</p>

DOI： 10.11499/sicejl.62.564

CiNii Research

その他リンク： http://id.ndl.go.jp/bib/033073755

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This note revisits extended Linear Matrix Inequality (LMI) formulation of performance analysis, which incorporates static multiplier, for parametrically multi-affine discrete-time Linear Time-Invariant Parameter-Dependent (LTIPD) and Linear Periodically Time-Varying (LPTV) systems using lifting technique. Almost the same analysis conditions for parametrically affine discrete-time LTIPD/LPTV systems as the ones shown in this note have already been proposed in the literature, we thus focus on the simple derivations of the conditions using only Elimination lemma. To this end, a variant of extended LMI formulation, whose dimensional sizes are slightly larger than the conventional formulation with additional auxiliary matrices, is proposed in this note. It is also shown that our derived variant directly leads to a parametrically multi-affine extended LMI formulation for our addressed problem.

DOI： 10.1016/j.ifacol.2023.10.074

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper gives a theoretical analysis of the robustness of servo systems with disturbance observers. The disturbance observers have been used as an easy way to enhance the robustness of servo systems because of their simple structure. However, the effectiveness has yet to be theoretically proved. Therefore, this paper aims to clarify the advantage of the disturbance observer. This paper considers the servo system consisting of a servo compensator and a disturbance observer. The servo system has robustness in suppressing the response variations against the system uncertainties. It is theoretically shown that the robustness comes from the systems having zeros of multiplicity two at s = 0, while the systems are type-1 servo systems. A numerical example is provided to confirm the theoretical result and to demonstrate the effectiveness of disturbance observers.

DOI： 10.1016/j.ifacol.2023.10.454

Scopus

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担当区分：最終著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11511/jacc.66.0_1066

CiNii Research

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This study addresses performance improvement of a calibration-free visual feedback controller proposed in our previous work. In our previous work, lens distortion is compensated by robust controllers designed using the nominal model of the generalized plant model containing lens distortion parameter. In contrast, we examine the effect of the supposed nominal model which is used in robust controller design. That is, we design visual feedback controllers using artificially set nominal models from the supposed parametric models. The results of numerical simulations reveal the performance improvement of the controllers designed by our new method compared to our previous result.

DOI： 10.1109/IECON51785.2023.10311677

Scopus

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記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11511/jacc.66.0_531

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）

This article considers the synthesis of feedback controllers for a class in which strong robust stability is required against sensing errors. The motivation dealing with this class arises from the stabilization problem of a cart-driven inverted pendulum by visual feedback control using a fisheye lens. While fisheye lenses guarantee a wide-angle of view, a large image distortion at off-center area is inevitable. Therefore this study first derives a geometric measurement model of a pendulum angle using a general fisheye lens model. A new design method for robust controllers for our problem is then proposed. Finally, a robust feedback controller that allows lens distortion is designed. The effectiveness of the controller based on the proposed model and the proposed design method is verified through numerical simulations and experiments.

DOI： 10.1109/TIE.2021.3127034

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This brief develops a sliding mode sensor fault-tolerant control scheme for a class of linear parameter varying (LPV) systems. It incorporates a sliding mode observer that reconstructs the unknown sensor faults based on only the system inputs and outputs. The reconstructed sensor faults are used to compensate for the corrupted sensor measurements before they are used in the feedback controller. Provided accurate fault estimates can be computed; near nominal control performance can be retained without any controller reconfiguration. Furthermore, the closed-loop stability of the fault-tolerant control (FTC) scheme, involving both a sliding mode controller and a sliding mode observer, is rigorously analyzed. The proposed scheme is validated using the Japan Aerospace Exploration Agency's Multipurpose Aviation Laboratory (MuPAL-α) research aircraft. These flight tests represent the first validation tests of a sliding mode sensor FTC scheme on a full-scale aircraft.

DOI： 10.1109/TCST.2021.3096946

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This paper considers the conversion problem from strictly proper non-structured Linear Time-Invariant (LTI) controllers, which are designed <i>a priori</i>, to strictly proper “observer-structured LTI controllers”, whose structure is similar to but not exactly the same as the so-called “Luenberger observer-based LTI controllers”, for LTI Parameter-Dependent (LTIPD) plant systems. We parametrize the state-space matrices of the observer-structured controllers with those of the non-structured controllers, one free matrix and a state transformation matrix, and propose a method to obtain the optimal state transformation matrix with respect to the convergence of non-zero initial plant state. We also clarify the relation between our method and an existing one for full-order controllers for LTI plant systems.</p>

DOI： 10.9746/sicetr.58.255

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/sicetr/58/5/58_255/_pdf

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This note addresses the parameter estimation problem in the input matrices for Linear Time-Invariant (LTI) systems under <i>a priori</i> given frequency domain constraints. The constraints are incorporated into the weighted least square method with help of Generalized KYP (GKYP) lemma, the proposed method is thus formulated in terms of Linear Matrix Inequalities (LMIs). A practical example, i.e. the linearized lateral-directional motion model of an airplane, is included to demonstrate the effectiveness of our method.</p>

DOI： 10.9746/sicetr.58.100

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/sicetr/58/2/58_100/_pdf

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11511/jacc.65.0_1442

CiNii Research

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This letter proposes a first order sliding mode observer for the purpose of simultaneously estimating the unknown input time delay and reconstructing the loss of effectiveness in a model of an actuator. The adaptive algorithm is driven by the 'equivalent output error injection' signal associated with the sliding motion. Sufficient conditions are given to ensure finite time convergence of the state estimation error system, ensuring both the time delay estimation error and the estimation error associated with the actuator fault converge to a small region around zero. The efficacy of the approach has been evaluated via both a numerical simulation and flight data validation.

DOI： 10.1109/LCSYS.2021.3090654

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper is concerned with the design of robust controllers with observers. In general, the nominal model is selected as the state-space model for the observer to estimate the states even if the plant has uncertainties. However, the properness of this strategy is ambiguous. This paper evaluates the properness of selecting the nominal model for state estimation of the plant with uncertainties. Sato (2018a) proposed a new type of controller so-called observer-structured controller. The controller introduces additional freedom for selecting the state-space model used for the state estimation. With this type of controller, this paper demonstrates that the adequate selection of estimation model improves the closed-loop control performance through numerical examples.

DOI： 10.1016/j.ifacol.2022.09.346

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper deals with the automatic transition methodologies for a QTW (Quad Tilt Wing) small VTOL UAV, which features tandem tilt wings with propellers mounted at the mid-span of each wing. The automatic transition algorithm was designed aiming to implement full automatic transition flight capabilities to the existing QTW auto-flight system. The algorithm changes tilt angle automatically to maintain the aircraft within the safe flight envelope while it also simultaneously coordinates navigation and guidance controllers, which is the main contribution of this paper. The algorithm was installed to the QTW UAV platform and a full transition flight test including vertical take-off, accelerating transition, cruise, decelerating transition and hover landing was successfully accomplished.

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This article presents the design, verification, and validation of a fault tolerant linear parameter varying controller for JAXA's MuPAL-α aircraft. The design focuses on the synthesis of a lateral/directional LPV controller robust to velocity changes and actuator uncertainty, and with the scheduling variable chosen to make it fault tolerant to aileron and/or rudder loss-of-efficiency faults. The verification activities include linear, frequency and time, analyses as well as time-domain simulations –the latter with the LPV controller as it will be implemented in the aircraft. The validation is performed in the so-called Aircraft-In-the-Loop, which is best described as a type of aircraft Iron-Bird test-bench where the full aircraft is connected in the hangar to an external computer that allows to introduce exogenous effects (such as wind/gust) while using pilot, or also computer user-defined, commands. The verification and validation results show very good robustness and fault tolerance characteristics of the LPV controller for a wide set of fault conditions and speeds. The article discusses in detail the design and implementation issues for such type of controllers.

DOI： 10.1016/j.jfranklin.2021.02.040

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

We address the conversion problem from a priori designed unstructured Linear Time-Invariant (LTI) controllers to observer-structured LTI controllers, whose structure is similar to but is not exactly the same as the so-called “Luenberger observer-based controllers”, for Linear Parameter-Varying (LPV) or LTI Parameter-Dependent (LTIPD) plant systems. For this problem, we propose a method by designing appropriate state transformation matrices which minimize the errors between plant systems' states and transformed controllers' states for external inputs via parametrically multi-affine Linear Matrix Inequality (LMI) conditions. The proposed method embeds existing LTI controllers with the ability of observers while their control performance is unchanged. We introduce a numerical example and illustrate the usefulness of our method by embedding observer property to an a priori designed H<inf>∞</inf> flight controller.

DOI： 10.1016/j.ifacol.2022.09.317

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This note addresses the conversion problem from unstructured Linear Parameter-Varying (LPV) controllers, which are designed a priori for LPV plant systems possessing parametric uncertainties as well as scheduling parameters, to observer-structured LPV controllers. In general, LPV controllers designed using parametrically dependent Linear Matrix Inequalities (LMIs) have no special structures. On this issue, we propose "observer-structured LPV controllers"which can be defined even for LPV plant systems without knowledge of the nominal state-space matrices of the LPV plant systems, and we address the conversion problem from a priori designed unstructured LPV controllers to observer-structured LPV controllers in order to embed observer property without changing controllers' input-to-output properties. To this end, we first parametrize the state-space matrices of observer-structured LPV controllers using those of the unstructured LPV controllers, single free matrices and constant state transformation matrices, and then give a formulation in terms of parametrically multi-affine LMIs to obtain the optimal constant state transformation matrices with respect to induced L2/l2 norm from external input to plant state estimation errors. A numerical example is introduced to demonstrate the usefulness of our propositions.

DOI： 10.1109/CDC51059.2022.9992585

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

In this article several robust control design techniques are compared via their application to the fault tolerant control problem for the lateral/directional motion of JAXA's research aircraft MuPAL-α. The techniques used include: (i) a single, passive-FTC, robust structured H∞ design, (ii) single, active-FTC, robust standard and structured H∞ designs, (iii) manual scheduling schemes from the previous designs, (iv) a self-scheduled structured H∞ design, and (v) a linear parameter varying design. All the designs were implemented in the onboard computer and validated in the so-called Aircraft-In-the-Loop configuration, which entails the operation of the full aircraft in fly-by-wire mode in the hangar. The results show that all the approaches provided acceptable solutions, but with the last two techniques resulting in a more homogeneous performance throughout the fault and command scenarios tested.

DOI： 10.1016/j.ifacol.2022.11.291

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

In this paper, we consider designing Fault-Tolerant Flight Control (FTFC) system based on the almost strictly positive real (ASPR) based two-degree-of-freedom controller comprising an adaptive output feedback control and an output predictive feedforward control to attain stable output tracking control. The aircraft model considered here has uncertain time-delay and uncertain deterioration of efficiency at the control input channel. To deal with such a time-delay uncertain system, we design an ASPR based two-degree-of-freedom controller comprising an adaptive output feedback control and an output predictive feedforward control. The effectiveness of the proposed method will be confirmed through numerical simulations with the longitudinal motion model of JAXA's research airplane MuPAL-α.

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper concerns a method of constructing observers for the plant with uncertainties. In a conventional design, the nominal system matrix is chosen as the system matrix of the observer for the system with/without the uncertainties. However, the rationale of this strategy is ambiguous. This paper investigates the degree of freedom in selecting the system matrix of the observer. The observer-structured controllers designed with freedom of the selection are evaluated in the H2 control and estimation performances.

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper addresses the design problem of Gain-Scheduled Output Feedback (GSOF) controllers, in which causality with respect to (w.r.t) scheduling parameters in the GSOF controllers is kept, for continuous-/discrete-time Linear Parameter-Varying (LPV) systems using Parameter-Dependent Lyapunov Functions (PDLFs). In general, continuous-time GSOF controllers designed by conventional methods, i.e. so-called change-of-variables using PDLFs, depend on the derivatives of scheduling parameters, and discrete-time GSOF controllers designed by conventional methods or extended Linear Matrix Inequality (LMI) technique using parameter-dependent auxiliary matrices both depend on the one-step-ahead scheduling parameters. These mean that the designed GSOF controllers are not implementable to practical systems due to the non-causality w.r.t. scheduling parameters. On this issue, we propose a formulation which circumvents the causality problem by replacing the term that introduces the causality issue with another term via the reverse use of the Elimination lemma which is also known as “S-variable” approach. A toy example and a practical example (lateral-directional motion control around wing level flight of JAXA's research airplane MuPAL-α) are included to demonstrate the effectiveness compared to the existing methods.

DOI： 10.1016/j.automatica.2021.109569

Scopus

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper presents a design example of structured H∞ control-based passive Fault-Tolerant Flight Control (FTFC) for the longitudinal motion of a research airplane MuPAL-α, and also presents the results of Hardware-In-the-Loop Simulation (HILS) tests using the actual MuPAL- α. The FTFC comprising PID and feedforward gains is designed using hinfstruct command implemented in MATLAB® for the linearized longitudinal airplane motion model combined with a Linear Time-Invariant Parameter-Dependent (LTIPD) system representing the modeling errors of the onboard actuator and a Linear Parameter-Varying (LPV) system representing the possible actuator efficiency reduction. As hinfstruct command cannot handle parameter-dependent systems directly, we adopt two-step design, viz., we first obtain controller gain candidates which are common for multiple Linear Time-Invariant (LTI) models selected from the combined system comprising the longitudinal motion model, the LTIPD system and the LPV system with specifically fixed parameter values, and we then analyze the actual performance using the combined system via Linear Matrix Inequalities (LMIs) under the supposed parameter variation rate bounds.

DOI： 10.1109/MED51440.2021.9480174

Scopus

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper is concerned with the design problem of causal gain-scheduled output feedback controllers for linear parameter-varying systems using parameter-dependent Lyapunov functions. This research topic has already been addressed by several researchers, and several effective methods have been correspondingly proposed in terms of parametrically dependent matrix inequalities. This paper addresses the dual formulation of one of the methods, and successfully derives the counterpart result in continuous-time case but points out the intractability of deriving the counterpart result in discrete-time case. It is also shown, in discrete-time case, that the intractability disappears and a design method similar to an existing method is successfully derived if the causality with respect to scheduling parameters is abandoned, namely, if one-step ahead scheduling parameters are available. A toy example is introduced to confirm that, in continuous-time case, the derived dual formulation gives the same performance as the previously proposed method for the dual state-space representation of the example.

DOI： 10.1080/18824889.2021.1953304

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper presents a design example of structured H-control-based flight controller for the lateral-directional motions of JAXA's research airplane MuPAL-α using MATLAB® Robust Control ToolboxTM. To be more specific, the design problem of Luenberger observer-based flight controllers is addressed. Even if the controllers' structure is a priori supposed and fixed as Luenberger observer-based controllers, it does not always hold true that the controllers' states faithfully estimate the plants' states. We thus adopt two-step design approach to realize good control performance and good plants' states estimation simultaneously, viz, we first optimize H-control performance of the closed-loop system, and then optimize H-observer performance under slightly relaxed H-control performance constraint. In the second process, systune command is used, because multiple design requirements are simultaneously imposed. The control and observer performance are both examined by the Hardware-In-the-Loop Simulation (HILS) tests using the actual MuPAL-α.

DOI： 10.1109/CCTA48906.2021.9659230

Scopus

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担当区分：筆頭著者,　最終著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11511/jacc.64.0_1101

CiNii Article

CiNii Research

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This paper addresses the design problem of Luenberger observer-based robust iHi_∞ flight controllers for aircraft motion control. Structured Linear Time-Invariant (LTI) iHi_∞ controllers, which are merely sub-optimal with respect to the optimality of <i>H</i>_∞ norm in controllers' parameter space but are attractive due to the simpler structure than full-order <i>H</i>_∞ controllers, can be easily designed using MATLAB^® hinfstruct even for LTI Parameter-Dependent (LTIPD) and Linear Parameter-Varying (LPV) systems via two-step design. That is, controller gain candidates are firstly designed as common gains for multiple LTI models selected from the LTIPD or LPV systems with specific parameter values, and their practical performance is then examined for the LTIPD or LPV systems with rigorous analysis conditions. However, hinfstruct cannot handle multiple design specifications simultaneously, thus, it is not so easy to design practical flight controllers which should meet various requirements. This paper addresses the design problem of Luenberger observer-based robust <i>H</i>_∞ flight controllers using MATLAB^® systune, and demonstrates that such controllers can be designed with observer performance optimized under a priori specified scaled-<i>H</i>_∞ performance and controller gain constraints. The effectiveness of the controller is examined by Hardware-In-the-Loop Simulations (HILS) with JAXA's research airplane MuPAL-α. </p>

DOI： 10.2322/jjsass.69.72

CiNii Article

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/jjsass/69/2/69_69_72/_pdf

記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This paper reports the safety confirmation of flight control system of an Unmanned Aerial Vehicle (UAV) with a pair of high-aspect-ratio wings via nonlinear simulations and hardware-in-the-loop simulation tests with various flight conditions (steady winds, gusts, etc.). The UAV successfully had a safe flight in Taiki town in Hokkaido after the safety confirmation process. </p>

DOI： 10.2322/jjsass.69.42

CiNii Article

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/jjsass/69/1/69_69_42/_pdf

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This article presents a design example of Fault-Tolerant Flight Controllers (FTFCs) and their performance assessment via Hardware-In-the-Loop (HIL) tests with a real airplane. An observer-based robust H8 design approach is proposed where the states of the observers can be used as virtual sensors for Fault Detection and Isolation (FDI). Two observer-based robust H8 FTFCs against actuator faults are designed based on whether the observer performance is optimized or not. Their control and observer performances are compared via HIL tests with JAXA's research airplane MuPAL-a.

DOI： 10.1109/CDC42340.2020.9304244

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

To be able to maintain their performance, the Flight Control Systems in use on most transport aircraft should be endowed with resilient properties to deal with sensor/actuator faulty conditions or with any significant airframe changes. During the H2020 VISION project, several adaptive control designs have been developed by ONERA, and were flight tested to this end using the MuPAL-\alpha research aircraft of JAXA. One of these solutions involve a gain-scheduled controller designed off-line plus an estimation algorithm to track the time-varying parameters on-line, permitting the values of the main stability and control derivatives required to schedule the controller to be updated in real time. This paper focuses on the estimation part, and provides an experimental comparison of some results achieved in strictly similar conditions by using either frequency or time domain techniques. A new Hybrid Stabilized Recursive Least-Squares (HSRLS) is also proposed, as well as competing options regarding the aircraft modeling used by the estimator.

DOI： 10.1109/CCTA41146.2020.9206350

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper develops a sliding mode fault tolerant control scheme based on a Linear Parameter Varying (LPV) system representation of the plant. The scheme includes a control allocation component, which is capable of utilizing the available healthy actuators in the face of actuator faults/failures, in an effort to retain close to nominal fault free performance. The proposed scheme is validated using the Japan Aerospace Exploration Agency's Multi-Purpose Aviation Laboratory (MuPAL-α) research aircraft. The flight test results demonstrate good lateral-directional state tracking performance with no visible performance degradation in the presence of rudder and aileron faults.

DOI： 10.1016/j.automatica.2020.108829

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper addresses the design problem of continuous-/discrete-time observer-based Gain-Scheduled Output Feedback (GSOF) controllers for Linear Parameter-Varying (LPV) systems, in which some of the state-space matrices are multi-affine with respect to parameters, with the simultaneous design of scaling matrices for multiple uncertainty blocks under the supposition that inexact scheduling parameters are available. In the design of GSOF controllers for practical systems in induced L<inf>2</inf>∕l<inf>2</inf>-norm control framework, the following features are to be incorporated; i) structured and easily-understandable controllers are preferable to enhance the practicality, ii) the scaling matrices related to multiple uncertainty blocks which represent various design specifications are also to be designed to reduce conservatism, and iii) one-shot design is preferable to prevent numerical problems in iterative algorithm. However, in general, neither the design problems of the structured controllers nor the simultaneous design of controllers and the performance scaling matrices are formulated in terms of Linear Matrix Inequalities (LMIs). Under the supposition that the uncertainties in the provided scheduling parameters are bounded (this supposition holds true for proportional uncertainties and for absolute uncertainties as well as for the mixed ones of them), we derive a new tractable one-shot multi-affine condition for our problem via dilated/extended LMI technique under some mild assumptions for LPV systems. A numerical example well illustrates the effectiveness of our method.

DOI： 10.1016/j.sysconle.2020.104632

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper addresses the design problem of robust controllers, which are composed of state observers and state-feedback controllers, for linear time-invariant parameter-dependent (LTIPD) systems. The design problems for continuous-time and discrete-time LTIPD systems are both addressed. The state-space matrices of the LTIPD systems are supposed to be multiaffine with respect to time-invariant parameters, and the supposed uncertainty blocks, which have an ability to define various design requirements, are characterized by scaling matrices, e.g., D- and (D, G)-scaling. We propose a tractable condition for the simultaneous design of robust controllers and scaling matrices via dilated linear matrix inequality technique. A numerical example demonstrates the effectiveness of our method.

DOI： 10.1109/TAC.2019.2919811

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This article presents the design and evaluation of a robust C^*control law through Hardware-In-the-Loop Simulation (HILS) of JAXA's research aircraft called Multi-Purpose Aviation Laboratory (MuPAL-a). The C^*control law, which is a widely used flight control architecture in aviation industries, is designed using structured H<inf>8</inf>synthesis. This design method provides robustness of the controller for flight condition changes and uncertainties associated with the dynamics of MuPAL-a. HILS tests allow on-ground evaluation of controllers using actual actuators. The HILS results show that the designed controller adequately tracks pilot commands in the presence of airspeed variation, uncertainties in the modeling of the onboard actuators, and wind gust.

DOI： 10.1016/j.ifacol.2020.12.1927

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The problem of designing the longitudinal flight controller for a quad-tilt-wing unmanned aerial vehicle to achieve robust performance under constraints on the controller structure is considered. An approach based on μ-synthesis is proposed, in which a nonparametric inverse multiplicative uncertainty description is employed to account for the uncertainties of the aircraft attitude dynamics at each operating condition, with specific reference to variations in the number of unstable modes. The resulting μ-synthesis problem with a frequency-dependent weighting function, the structure of which is defined a priori, is reformulated as a structured H<inf>∞</inf> problem and solved by means of available MATLAB software. Simulation results are presented in order to show the effectiveness of the approach.

DOI： 10.2514/1.G005080

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This note presents the pilot assessment of a Fault-Tolerant Control (FTC) law for elevator efficiency reduction via Hardware-In-the-Loop Simulations (HILS) with a research airplane MuPAL-α. The FTC is supposed to be a PID controller from the viewpoint of the practicality and applicability viz., conventional Stability/Control Augmentation System (S/CAS) structure is adopted. The PID-FTC is designed with the consideration of onboard actuator uncertainties as well as the possible loss of efficiency (from 0% loss up to 80% loss) in the framework of H∞ control with hinfstruct command implemented in Matlab®. In HILS, the pilot is required to have steady climb and descent under the condition that the elevator efficiency is gradually reduced in a software level. HILS results indicate that the designed PID-FTC works well when the elevator efficiency decreases even under wind gust conditions.

DOI： 10.1016/j.ifacol.2020.12.1959

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper addresses parameter estimation problem of Continuous-/Discrete-Time (CT/DT) Linear Time-Invariant (LTI) systems, whose gain properties should satisfy given constraints in a priori specified frequencies, using measured data. The following are supposed in our problem: i) only input matrix has parameters to be estimated; ii) the state and the input are both measured, and the derivative of the state is also measured in CT case, and iii) the gain constraints in specified frequency ranges are given beforehand. Under these suppositions, a formulation to minimize the difference between the measured state derivative and the expected state derivative (in CT case) or the difference between the measured one-step-ahead state and the expected one-step-ahead state (in DT case) in Euclidean norm with the supposed gain constraints satisfied is given in terms of Linear Matrix Inequality (LMI). The effectiveness of the proposed method is demonstrated by an academic example in DT case as well as flight data obtained by JAXA's airplane in CT case.

DOI： 10.1016/j.ifacol.2020.12.500

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This paper addresses the design problem of Fault-Tolerant Control (FTC) for airplane longitudinal motions against possible elevator efficiency reduction. The supposed FTC is composed of a feedforward gain and the conventional airplane control system, i.e. Stability/Control Augmentation System (S/CAS). The FTC is required to maintain good tracking performance with respect to pitch angle control under time-invariant plant modeling errors as well as time-varying possible elevator faults. The design problem is then formulated as structured robust <i>H</i>_∞ controller design for parameter-dependent systems, i.e. single structured <i>H</i>_∞ controller design for parameter-varying plant models. It is hard to obtain the globally optimal controllers for the problem due to the structural constraint for the controllers and the parameter-varying plant models. We thus adopt two-step design, viz., we first design a single common structured <i>H</i>_∞ controller for finitely many plant models using non-smooth optimization technique, which has been implemented to Matlab^® as hinfstruct, under the supposition that the elevator faults are time-invariant, and we then check the control performance of the designed FTC for the parameter-varying closed-loop system via Linear Matrix Inequality (LMI) condition. The control performance is examined via linear simulations as well as hardware-in-the-loop simulations. </p>

DOI： 10.2322/jjsass.68.223

CiNii Article

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/jjsass/68/6/68_68_223/_pdf

担当区分：最終著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This paper confirms the applicability of moment control by electric propellers. Normal and reverse rotation of propellers can improve the moment control performance than only using normal rotation propellers. In addition, it is verified that moment control can be improved by using the distributed thrust in addition to the existing control devices due to the slipstream effect. </p>

DOI： 10.2322/jjsass.68.128

CiNii Article

CiNii Research

その他リンク： http://id.ndl.go.jp/bib/030481678

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>This paper addresses the design problem of Gain-Scheduled (GS) flight controllers, in which only inexact scheduling parameters are available, for aicraft motion control. Most of existing design methods for GS controllers implicitly suppose that exact scheduling parameters are available. However, this does not always hold true in practice, which has invoked the research on the design of GS controllers depending on inexact scheduling parameters. We design a GS flight controller for the lateral-directional motion of JAXA's fixed-wing experimental aircraft MuPAL-α using a recently proposed design method which guarantees the pre-defined control performance under the bounded uncertainties in the provided scheduling parameters. We examine the applicability and performance of our controller by flight tests. </p>

DOI： 10.2322/jjsass.68.12

CiNii Article

CiNii Research

その他リンク： http://id.ndl.go.jp/bib/030253682