CERES :: Browsing by Author "Ignatyev, Dmitry I."

Browsing by Author "Ignatyev, Dmitry I."

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Open Access
Bayesian calibration for multiple source regression model
(Elsevier, 2018-08-20) Ignatyev, Dmitry I.; Shin, Hyosang; Tsourdos, Antonios
In large variety of practical applications, using information from different sources or different kind of data is a reasonable demand. The problem of studying multiple source data can be represented as a multi-task learning problem, and then the information from one source can help to study the information from the other source by extracting a shared common structure. From the other hand, parameter evaluations obtained from various sources can be confused and conflicting. This paper proposes a Bayesian based approach to calibrate data obtained from different sources and to solve nonlinear regression problem in the presence of heteroscedastisity of the multiple-source model. An efficient algorithm is developed for implementation. Using analytical and simulation studies, it is shown that the proposed Bayesian calibration improves the convergence rate of the algorithm and precision of the model. The theoretical results are supported by a synthetic example, and a real-world problem, namely, modeling unsteady pitching moment coefficient of aircraft, for which a recurrent neural network is constructed.
Open Access
Fault detection, isolation and adaptive augmentation for incremental backstepping flight control
(Elsevier, 2021-04-14) Ignatyev, Dmitry I.; Shin, Hyosang; Tsourdos, Antonios;
Uncertainties caused by unforeseen malfunctions of the actuator or changes in aircraft behavior could lead to aircraft loss of control during flight. The paper presents a Two-Layer Framework (TLF) augmenting Incremental Backstepping (IBKS) control algorithm designed for an aircraft. IBKS uses angular accelerations and current control deflections to reduce the dependency on the dynamics model. Nevertheless, knowledge of the control effectiveness is still required for proper tracking performance and stability guarantee and becomes essential in a case of failure. The proposed TLF is designed to detect possible problems such as a failure or presence of unknown actuator dynamics and to adapt the control effectiveness. At the first layer, the system performs detection and isolation of possible failures. After a problem being detected and isolated, the algorithm initiates the second-layer adaptation of the individual effectiveness of the failed control effector. For some critical scenarios, when the input-affine property of the IBKS is violated, e.g., for a combination of multiple failures, the IBKS could lose stability. Meanwhile, the proposed TLF-IBKS algorithm has improved tracking and stability performance
Open Access
Gaussian process adaptive incremental backstepping flight control
(AIAA, 2021-12-29) Ignatyev, Dmitry I.; Shin, Hyo-Sang; Tsourdos, Antonios
The presence of uncertainties caused by unforeseen malfunctions in the actuation system or changes in aircraft behaviour could lead to aircraft loss of control during flight. The paper proposes almost model-independent control law combining recent developments in nonlinear control theory, data-driven methods, and sensor technologies by considering Gaussian Processes Adaptive augmentation for Incremental Backstepping control (IBKS) algorithm. IBKS uses angular accelerations and current control deflections to reduce the dependency on the aircraft model. However, it requires knowledge of control effectiveness. Conducted research shows that if the input-affine property of the IBKS is violated, e.g., in severe conditions with a combination of multiple failures, the IBKS can lose stability. Meanwhile, the GP-based estimator provides fast identification and the resultant GP-adaptive IBKS algorithm demonstrates improved stability and tracking performance. The performance of the algorithm is validated using a large transport aircraft flight dynamics model.
Open Access
A global-local meta-modelling technique for model updating
(Elsevier, 2023-10-09) Dessena, Gabriele; Ignatyev, Dmitry I.; Whidborne, James F.; Zanotti Fragonara, Luca
The finite element model updating procedure of large or complex structures is challenging for engineering practitioners and researchers. Iterative methods, such as genetic algorithms and response surface models, have a high computational burden for these problems. This work introduces an enhanced version of the well-known Efficient Global Optimisation technique to address this issue. The enhanced method, refined Efficient Global Optimisation or rEGO, exploits a two-step refinement and selection technique to expand the global search capability of the original method to a global–local, or hybrid, search capability. rEGO is tested and validated on four optimisation test functions against the original methods and genetic algorithms with different settings. Good results in terms of precision and computational performance are achieved, so an application for model updating is sought. A penalty function for the finite element model updating is identified in residuals of the modified total modal assurance criterion. Finally, rEGO for finite element model updating is implemented on a hybrid, numerical and experimental, case study based on a well-known experimental dataset and on a higher dimension finite element model of a wing spar. Satisfactory results in terms of precision and computational performance are achieved when compared to the original methods and genetic algorithms, needing two orders of magnitude fewer evaluations and achieving comparable results in terms of precision.
Open Access
Ground vibration testing of a flexible wing: a benchmark and case study
(MDPI, 2022-08-10) Dessena, Gabriele; Ignatyev, Dmitry I.; Whidborne, James F.; Pontillo, Alessandro; Zanotti Fragonara, Luca
Beam-like flexible structures are of interest in many fields of engineering, particularly aeronautics, where wings are frequently modelled and represented as such. Experimental modal analysis is commonly used to characterise the wing’s dynamical response. However, unlike other flexible structure applications, no benchmark problems involving high-aspect-ratio flexible wings have appeared in the open literature. To address this, this paper reports on ground vibration testing results for a flexible wing and its sub-assembly and parts. The experimental data can be used as a benchmark and are available to the aeronautical and structural dynamics community. Furthermore, non-linearities in the structure, where present, were detected. Tests were performed on the whole wing as well as parts and sub-assembly, providing four specimens. These were excited with random vibration at three different amplitudes from a shaker table. The modal properties of a very flexible high-aspect-ratio wing model, its sub-assembly and parts, were extracted, non-linear behaviour was detected and the experimental data are shared in an open repository.
Open Access
Ground vibration testing of a high aspect ratio wing with revolving clamp
(ICAS, 2022-11-28) Dessena, Gabriele; Ignatyev, Dmitry I.; Whidborne, James F.; Pontillo, Alessandro; Zanotti Fragonara, Luca
The advancements in the aeronautical industry and research on materials and manufacturing methods in the last 70 years have been shifting the paradigm of wing design to high aspect ratio flexible wings. These wings can show a varying behaviour in different operating conditions, as per the nature of their geometry and materials. This work proposes a case study of a high aspect ratio flexible wing in order to study the effect of operating conditions on its structural properties. To test different operating conditions on the ground, a revolving clamp is designed to attach the specimen to a clamp-on shaker. A clear relationship between the wing’s modal properties, and so structural properties, and the angle the clamp sets is found.
Open Access
Group design project in control engineering: Adapting to COVID-19 pandemic
(Elsevier, 2021-11-18) Ignatyev, Dmitry I.; Shin, Hyosang; Zolotas, Argyrios; Tsourdos, Antonios
Group Design Project (GDP) is a common education strategy in engineering. However, due to the COVID-19 pandemic, GDP cannot be fulfilled in a typical lab condition. The paper describes an example of delivering intensive hands-on, group project-based engineering course Autonomous Vehicle Dynamics and Control at Cranfield University. The project was designed to be implemented using modern simulation tools. As a result, students have not only obtained a better understanding of the engineering areas but also learned the usage of essential engineering and IT tools. The students obtained skillsets useful in modern engineering applications, where a simulation environment could improve the quality of the system before deployment and reduce a development cost.
Open Access
Hybrid terrain traversability analysis in off-road environments
(IEEE, 2022-03-22) Leung, Tiga Ho Yin; Ignatyev, Dmitry I.; Zolotas, Argyrios
There is a significant growth in autonomy level in off-road ground vehicles. However, unknown off-road environments are often challenging due to their unstructured and rough nature. To find a path that the robot can move smoothly to its destination, it needs to analyse the surrounding terrain. In this paper, we present a hybrid terrain traversability analysis framework. Semantic segmentation is implemented to understand different types of the terrain surrounding the robot; meanwhile geometrical properties of the terrain are assessed with the aid of a probabilistic terrain estimation. The framework represents the traversability analysis on a robot-centric cost map, which is available to the path planners. We evaluated the proposed framework with synchronised sensor data captured while driving the robot in real off-road environments. This thorough terrain traversability analysis will be crucial for autonomous navigation systems in off-road environments.
Open Access
Identification of flexible structures dynamics.
(Cranfield University, 2023-04) Dessena, Gabriele; Ignatyev, Dmitry I.; Whidborne, James F.; Zanotti Fragonara, Luca
The pursuit of aerodynamic efficiency and the advances in materials technology, particularly in composite material, has contributed to shifting the paradigm of wing design to high aspect ratio wings. Increasing the span, for decreasing drag, and using composite lightweight materials make the new wing very flexible and prone to nonlinear dynamic behaviour. With nonlinearities, increasing challenges arise for the identification and modelling of the wing. These challenges cannot be overlooked for flexible structures as these models are critical for the prediction of aeroelastic phenomena. Hence, it is fundamental to expand the knowledge of the behaviour of these structures through the identification and modelling of sample flexible wing models. In this work, a series of methods and approaches are proposed and employed for the identification and modelling of a flexible wing. First, a system identification technique in the frequency domain, the Loewner Framework, is applied for modal parameters extraction in mechanical systems for structural health monitoring. This new technique, with a linear reduced order model, is used to characterise the flutter behaviour of a flexible wing. The results are compared to similar techniques. A thorough experimental campaign is run on a flexible wing model to characterise its nonlinear behaviour and the underlying linear system. In particular, nonlinearities are detected, identified and quantified. Then, a meta-model technique based on Kriging, the refined Efficient Global Optimisation, is proposed for finite element model updating. First, the technique is used for damage detection in benchmark structures, then, it is employed for the validation of component-based strategies for model updating of a flexible wing.
Open Access
Interplay of unsteady aerodynamics and flight dynamics of transport aircraft in icing conditions
(Elsevier, 2020-06-11) Ignatyev, Dmitry I.; Khrabrov, Alexander N.; Kortukova, A. I.; Alieva, D. A.; Sidoryuk, Maria E.; Bazhenov, Sergey G.
Airframe icing causes significant degradation of aerodynamic characteristics and influences the flight safety. Wind tunnel study of longitudinal steady and unsteady aerodynamic characteristics of a transport aircraft in icing conditions is carried out in order to develop mathematical model of aerodynamics in the extended flight envelope. The wind tunnel results are validated through flight tests conducted for the real aircraft. Large, glaze-horn ice shapes, corresponding to holding flight phase, are considered. Influence of an ice protection system as well as its failure is examined. Effect of icing on the unsteady aerodynamics characteristics is studied not only through wind tunnel tests but also via analysis of subsequent influence on the flight dynamics of the aircraft. The conducted study shows that the ice shapes of the holding phase leads to reduced stall angle of attack (AoA), maximum lift, and longitudinal damping. Flight dynamics analysis demonstrates that dangerous aircraft behaviour in the form of high AoA departure and limit cycle oscillations (LCO) can be observed at smaller elevator deflections for the iced aircraft. Taking into account icing influence on the unsteady aerodynamics in the flight dynamics simulations revealed degradation of the dynamic response and deterioration of phase portraits of the system. Even for small AoA and elevator deflection the aircraft might be trapped into the basin of attraction of high-AoA LCO. In addition, incorporating icing effects in unsteady aerodynamics manifest larger amplitude of LCO.
Open Access
A Kriging approach to model updating for damage detection
(Springer, 2022-06-16) Dessena, Gabriele; Ignatyev, Dmitry I.; Whidborne, James F.; Zanotti Fragonara, Luca
For complex or large structures, the model updating process can be long and tedious and numerical methods can be computationally expensive. Hence, practitioners and researchers often resort to meta-modelling techniques when large problems are met. Even so, traditional methodologies, such as the Efficient Global Optimisation, can be slow and give sub-optimal results. This work proposes a new methodology for the model updating of numerical systems based on a novel Kriging approach for the scope of damage detection and quantification. The framework proposed is based on a global-local optimisation strategy recently developed by the authors, the refined Efficient Global Optimisation, herein used to tweak finite element models’ parameters to match the modal data extracted from a numerical system by using the residuals of the modified total modal assurance criterion. The main advantage to existing direct optimisation and meta-modelling frameworks is the more efficient use of computational e ort for higher dimensional problems, which is verified with the use of a numerical system.
Open Access
Nonlinear analysis for wing rock system with adaptive control
(AIAA, 2021-12-29) Li, Dongyang; Ignatyev, Dmitry I.; Tsourdos, Antonios; Wang, Zhongyuan
Adaptive control has the potential to improve the performance and reliability of aircraft. However, the inherent nonlinearity of adaptive control causes difficulty in stability and robustness verification which is critical before entry into service. In this paper, the region of attraction (ROA) estimation using sum of squares (SOS) technique is explored for adaptive control systems. The problem of wing rock suppression by a model reference adaptive control (MRAC) serves as a benchmark example to demonstrate the effectiveness of the method. Considering the potential disturbance presented in measurement signals, the operative range of aircraft must be included in the ROA of the control system. Therefore, the ROA is evaluated using SOS polynomial optimization under various combinations of design parameters in the adaptive law, including adaptation rate and sigma modification values. This gives insight into the interactions of design parameters on the adaptive control performance.
Open Access
Nonlinear analysis for wing-rock system with adaptive control
(AIAA, 2022-07-25) Li, Dongyang; Tsourdos, Antonios; Wang, Zhongyuan; Ignatyev, Dmitry I.
Introduction The potential of adaptive control in improving the performance and reliability of control systems attracts researchers and engineers from different disciplines. However, the verification and validation of the flight control system regarding the modeling error, uncertainty, disturbance, and time delay is not an easy task due to the inherent nonlinearity of the problem as well as the lack of rigorous analysis tools for nonlinear systems [1–5].
Open Access
On-line learning and updating unmanned tracked vehicle dynamics
(MDPI, 2021-01-15) Strawa, Natalia; Ignatyev, Dmitry I.; Zolotas, Argyrios C.; Tsourdos, Antonios
Increasing levels of autonomy impose more pronounced performance requirements for unmanned ground vehicles (UGV). Presence of model uncertainties significantly reduces a ground vehicle performance when the vehicle is traversing an unknown terrain or the vehicle inertial parameters vary due to a mission schedule or external disturbances. A comprehensive mathematical model of a skid steering tracked vehicle is presented in this paper and used to design a control law. Analysis of the controller under model uncertainties in inertial parameters and in the vehicle-terrain interaction revealed undesirable behavior, such as controller divergence and offset from the desired trajectory. A compound identification scheme utilizing an exponential forgetting recursive least square, generalized Newton–Raphson (NR), and Unscented Kalman Filter methods is proposed to estimate the model parameters, such as the vehicle mass and inertia, as well as parameters of the vehicle-terrain interaction, such as slip, resistance coefficients, cohesion, and shear deformation modulus on-line. The proposed identification scheme facilitates adaptive capability for the control system, improves tracking performance and contributes to an adaptive path and trajectory planning framework, which is essential for future autonomous ground vehicle missions
Open Access
Region of attraction analysis for adaptive control of wing rock system
(Elsevier, 2021-11-01) Li, Dongyang; Ignatyev, Dmitry I.; Tsourdos, Antonios; Wang, Zhongyuan
This paper introduces a numerical method for region of attraction (ROA) estimation of the adaptive control system in polynomial form. A classical adaptive controller with sigma modification on suppressing the wing rock motion is revisited. Using the nonlinear analysis technique based on the sum of squares optimization, ROA of the origin is computed with respect to the potential measurement error. The obtained result gives a solid guarantee on the allowable initial conditions where the adaptive controller is still able to suppress the wing rock motion. It provides confidence for the adaptive controller operating under some unforeseen conditions in practice.
Open Access
Sparse online Gaussian process adaptation for incremental backstepping flight control
(Elsevier, 2023-02-28) Ignatyev, Dmitry I.; Shin, Hyosang; Tsourdos, Antonios
Presence of uncertainties caused by unforeseen malfunctions in actuation or measurement systems or changes in aircraft behaviour could lead to aircraft loss-of-control during flight. This paper considers sparse online Gaussian Processes (GP) adaptive augmentation for Incremental Backstepping (IBKS) flight control. IBKS uses angular accelerations and control deflections to reduce the dependency on the aircraft model. However, it requires knowledge of the relationship between inner and outer loops and control effectiveness. Proposed indirect adaptation significantly reduces model dependency. Global uniform ultimate boundness is proved for the resultant GP adaptive IBKS. Conducted research shows that if the input-affine property is violated, e.g., in severe conditions with a combination of multiple failures, the IBKS can lose stability. Meanwhile, the proposed sparse GP-based estimator provides fast online identification and the resultant controller demonstrates improved stability and tracking performance.
Open Access
Two-layer adaptive augmentation for incremental backstepping flight control of transport aircraft in uncertain conditions
(Elsevier, 2020-07-01) Ignatyev, Dmitry I.; Shin, Hyosang; Tsourdos, Antonios
Presence of uncertainties caused by unforeseen malfunctions in actuation system or changes in aircraft behaviour could lead to aircraft loss-of-control during flight. The paper presents Two-Layer Adaptive augmentation for Incremental Backstepping (TLA-IBKS) control algorithm designed for a large transport aircraft. IBKS uses angular accelerations and current control deflections to reduce the dependency on the aircraft model. However, it requires knowledge of control effectiveness. The proposed technique is capable to detect possible failures for an overactuated system. At the first layer, the system performs monitoring of a combined effectiveness and detects possible failures via an innovation process. If a problem is detected the algorithm initiates the second-layer algorithm for adaptation of effectiveness of individual control effectors. Filippov generalization for nonlinear differential equations with discontinuous right-hand sides is utilized to develop Lyapunov based tuning function adaptive law for the second layer adaptation and to prove uniform asymptotic stability of the resultant closed-loop system. Conducted simulation manifests that if the input-affine property of the IBKS is violated, e.g., in severe conditions with a combination of multiple failures, the IBKS can lose stability. Meanwhile, the proposed TLA-IBKS algorithm demonstrates improved stability and tracking performance.
Open Access
Two-layer on-line parameter estimation for adaptive incremental backstepping flight control for a transport aircraft in uncertain conditions
(Elsevier, 2019-11-25) Ignatyev, Dmitry I.; Shin, Hyosang; Tsourdos, Antonios
Presence of uncertainties caused by unforeseen malfunctions of the actuator or changes in aircraft behavior could lead to aircraft loss of control during flight. The paper presents two-layer parameter estimation procedure augmenting Incremental Backstepping (IBKS) control algorithm designed for a large transport aircraft. IBKS uses angular accelerations and current control deflections to reduce the dependency on the aircraft model. However, it requires knowledge of the control effectiveness. The proposed identification technique is capable to detect possible problems such as a failure or presence of unknown actuator dynamics even in case of redundancy of control actuation. At the first layer, the system performs monitoring of possible failures. If a problem in one of the control direction is detected the algorithm initiates the second-layer identification determining the individual effectiveness of the each control surface involved in this control direction. Analysis revealed a high robustness of the IBKS to actuator failures. However, in severe conditions with a combination of multiple failures and presence of unmodelled actuator dynamics IBKS could lost stability. Meanwhile, proposed control derivative estimation procedure augmenting the IBKS control helps to sustain stability.

Browsing by Author "Ignatyev, Dmitry I."

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