摘要 :
Unmanned Aerial Vehicles (UAVs) have become more and more popular, and how to control them through advanced control techniques becomes crucial. Although there are many different control methods that can be applied to the control o...
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Unmanned Aerial Vehicles (UAVs) have become more and more popular, and how to control them through advanced control techniques becomes crucial. Although there are many different control methods that can be applied to the control of UAVs, nonlinear control techniques are more practical since the inherent nonlinear features of most UAVs. In this paper, three widely used nonlinear control techniques including Feedback Linearization Control (FLC), Sliding Mode Control (SMC), and Backstepping Control (BSC) are investigated, implemented and experimentally tested on a unique quadrotor UAV (known as Qball-X4) test-bed available at the Networked Autonomous Vehicles (NAV) Lab in Concordia University. The advantages and disadvantages of these three control techniques with application to the Qball-X4 UAV are revealed through both simulation and experimental tests. Sliding mode control is well known for its capability of handling uncertainties, and is demonstrated to be the most robust and best performance controller for Qball-X4. Feedback linearization control and backstepping control are demonstrated a bit weaker than sliding mode control. Comparison of these three controllers is also carried out in both theoretical analysis and experimental testing under same flight conditions. Testing results and comparison show the different features of different control methods and provide a view on how to choose an appropriate controller for controlling the Qball-X4 and other UAVs under a specific condition.
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摘要 :
Unmanned Aerial Vehicles (UAVs) have become more and more popular, and how to control them through advanced control techniques becomes crucial. Although there are many different control methods that can be applied to the control o...
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Unmanned Aerial Vehicles (UAVs) have become more and more popular, and how to control them through advanced control techniques becomes crucial. Although there are many different control methods that can be applied to the control of UAVs, nonlinear control techniques are more practical since the inherent nonlinear features of most UAVs. In this paper, three widely used nonlinear control techniques including Feedback Linearization Control (FLC), Sliding Mode Control (SMC), and Backstepping Control (BSC) are investigated, implemented and experimentally tested on a unique quadrotor UAV (known as Qball-X4) test-bed available at the Networked Autonomous Vehicles (NAV) Lab in Concordia University. The advantages and disadvantages of these three control techniques with application to the Qball-X4 UAV are revealed through both simulation and experimental tests. Sliding mode control is well known for its capability of handling uncertainties, and is demonstrated to be the most robust and best performance controller for Qball-X4. Feedback linearization control and backstepping control are demonstrated a bit weaker than sliding mode control. Comparison of these three controllers is also carried out in both theoretical analysis and experimental testing under same flight conditions. Testing results and comparison show the different features of different control methods and provide a view on how to choose an appropriate controller for controlling the Qball-X4 and other UAVs under a specific condition.
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The design and development of an aircraft is a complex process, often taking place over 6-7 years, involving thousands of experts from many disciplines, and costing several billion dollars. Software tools have been developed to he...
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The design and development of an aircraft is a complex process, often taking place over 6-7 years, involving thousands of experts from many disciplines, and costing several billion dollars. Software tools have been developed to help manage this complexity, yet challenges remain with respect to their utility. Model-based approaches have been increasingly used to inform the development of software tools, in particular to facilitate an understanding between software developers and the domain experts for whom the software is being developed. Recent aircraft modeling research has identified challenges, such as interoperability, stemming from a lack of formal semantic structure. This paper discusses the current challenges faced in modeling literature, and proposes a formalized approach to semantic modeling of the aircraft design and development process. As certification is critical to aircraft design, the approach proposes using publicly available regulatory documentation to provide generic language and definitions, followed by an ontological model to develop a formal, aircraft domain-specific semantic structure prior to modeling for software-specific applications. Three modeling methods of process mapping, ontological modeling, and Unified Modeling Language (UML) are used to illustrate the advantages and limitations of a semantic approach to modeling. This paper uses the Advisory circular AC 21.101-1B Establishing the Certification Basis of Changed Aeronautical Products as a case study to illustrate the proposed approach. A formalized approach to modeling the aircraft design and development process contributes to structuring a model that adequately reflects the many entities and complex interactions that are implicit to this process. This paper concludes by identifying opportunities for further investigation of regulatory documentation to improve formal models of the aircraft design and development process.
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This paper describes a dual-loop control scheme for fault tolerant flight control system design. The dual-loop controller consists of an outer loop controller-so-called adaptive neural sliding mode control (ANSC) and an inner loop...
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This paper describes a dual-loop control scheme for fault tolerant flight control system design. The dual-loop controller consists of an outer loop controller-so-called adaptive neural sliding mode control (ANSC) and an inner loop controller designed by using nonlinear dynamic inversion (NDI) technique. The merits of adaptive neural network and sliding mode control scheme are that 1) the ability of adaptive neural network control to deal with unstructured uncertainty and 2) the ability of sliding mode control to guarantee transient response. Using timescale separation principal, the aircraft dynamics can be decomposed into fast and slow dynamics and the decomposed dynamics are inversed for NDI controllers. For real-time pilot simulation, one-stage inverse dynamics is used and the pilot inputs are translated to roll, pitch and yaw rate commands. For cascade NDI, two-stage dynamic inversion is used. The stability analysis of the proposed controller is performed using Lyapunov theory. To verify the effectiveness of the proposed control scheme, numerical simulation is performed for six degree-of-freedom nonlinear aircraft model while a failure occurs in longitudinal control surface. Simulation results demonstrate that closed-loop system has good performance while encountering lock-in-place, partial destruction and floating actuator failures.
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A novel fault-tolerant flight control system subject to actuator faults is studied in the framework of linear matrix inequality (LMI) approach. The deflection limits of control surfaces are taken into consideration explicitly in t...
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A novel fault-tolerant flight control system subject to actuator faults is studied in the framework of linear matrix inequality (LMI) approach. The deflection limits of control surfaces are taken into consideration explicitly in the design process. A set-invariance condition is proposed to obtain the design parameters. To improve the system performance, the regional pole placement problem is also addressed and the related LMI condition can be taken as an additional D-stability constraint. The proposed hybrid fault-tolerant control method combines the benefits of a nominal controller and a reliable controller. The reliable controller is switched in only when a fault has been detected by an observer-based fault detector, which reduces the conservativeness of a pure passive fault-tolerant control system. Same control structure is shared by both the nominal and reliable controllers, which simplify the design process further. Moreover, the stability of the closed-loop system can always be guaranteed in disturbance-free situation with zero initial residuals. The design techniques are applied to the pitch and roll attitude tracking control of a flying-wing unmanned aerial vehicle (UAV). Numerical studies indicate that stable output tracking is always achieved for both the wind-free and wind-present cases. When the wind is imposed, the stability of the closed-loop system is closely related to the observer gain which determines the detection delay.
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摘要 :
A novel fault-tolerant flight control system subject to actuator faults is studied in the framework of linear matrix inequality (LMI) approach. The deflection limits of control surfaces are taken into consideration explicitly in t...
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A novel fault-tolerant flight control system subject to actuator faults is studied in the framework of linear matrix inequality (LMI) approach. The deflection limits of control surfaces are taken into consideration explicitly in the design process. A set-invariance condition is proposed to obtain the design parameters. To improve the system performance, the regional pole placement problem is also addressed and the related LMI condition can be taken as an additional D-stability constraint. The proposed hybrid fault-tolerant control method combines the benefits of a nominal controller and a reliable controller. The reliable controller is switched in only when a fault has been detected by an observer-based fault detector, which reduces the conservativeness of a pure passive fault-tolerant control system. Same control structure is shared by both the nominal and reliable controllers, which simplify the design process further. Moreover, the stability of the closed-loop system can always be guaranteed in disturbance-free situation with zero initial residuals. The design techniques are applied to the pitch and roll attitude tracking control of a flying-wing unmanned aerial vehicle (UAV). Numerical studies indicate that stable output tracking is always achieved for both the wind-free and wind-present cases. When the wind is imposed, the stability of the closed-loop system is closely related to the observer gain which determines the detection delay.
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The design of hybrid-electric, distributed electric, and unconventional aircraft requires improving existing conceptual design methods. In particular, hybrid-electric aircraft require more integration between the traditional propu...
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The design of hybrid-electric, distributed electric, and unconventional aircraft requires improving existing conceptual design methods. In particular, hybrid-electric aircraft require more integration between the traditional propulsion system and the aircraft systems (i.e., the electrical power system, flight control systems, fuel system). Traditional conceptual design methods for aircraft systems rely on statistical data and focus mainly on weight estimation. This paper focuses on the fuel system, which shifts its role towards an energy storage system for hybrid-electric aircraft. This paper compares existing traditional weight estimation methods, proposes an updated empirical method and a new architecture-based approach. This architecture-based approach estimates the fuel system weight based on individual subsystems and major components from information available in conceptual design. The validation and the application to a hybrid-electric regional aircraft case study are presented to illustrate the capability of the new method. In summary, the architecture-based approach for the fuel system enables more detailed subsystem analysis as required in the next generation of multidisciplinary optimization frameworks, such as analysis of certifiability, safety, reliability, and thermal analyses.
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Hybrid-electric and all-electric aircraft are currently studied extensively at the conceptual level to explore reductions in fuel burn and emissions. Retrofitting and redesigning existing aircraft are potential paths toward achiev...
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Hybrid-electric and all-electric aircraft are currently studied extensively at the conceptual level to explore reductions in fuel burn and emissions. Retrofitting and redesigning existing aircraft are potential paths toward achieving hybrid and all-electric flight. New design tools need to be developed to support the study of these new aircraft configurations. In particular, novel design frameworks need to account for system-level aspects, such as the use of space, the required level of electrification, thermal aspects, safety, and maintainability. This paper presents a multidisciplinary design analysis (MDA) framework focusing on aircraft system integration for future aircraft. Specifically, this paper focuses on the integration between aircraft sizing and subsystem sizing tools in an MDA workflow. In addition, the authors include an improved physics-based subsystem sizing methods valid for smaller, commuter, or regional aircraft. The capabilities of the developed framework and tools are presented for a case study covering the redesign of the DO-228 with a hybrid-electric propulsion system in combination with the electrification of its systems architecture and different subsystem technologies.
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摘要 :
Hybrid-electric and all-electric aircraft are currently studied extensively at the conceptual level to explore reductions in fuel burn and emissions. Retrofitting and redesigning existing aircraft are potential paths toward achiev...
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Hybrid-electric and all-electric aircraft are currently studied extensively at the conceptual level to explore reductions in fuel burn and emissions. Retrofitting and redesigning existing aircraft are potential paths toward achieving hybrid and all-electric flight. New design tools need to be developed to support the study of these new aircraft configurations. In particular, novel design frameworks need to account for system-level aspects, such as the use of space, the required level of electrification, thermal aspects, safety, and maintainability. This paper presents a multidisciplinary design analysis (MDA) framework focusing on aircraft system integration for future aircraft. Specifically, this paper focuses on the integration between aircraft sizing and subsystem sizing tools in an MDA workflow. In addition, the authors include an improved physics-based subsystem sizing methods valid for smaller, commuter, or regional aircraft. The capabilities of the developed framework and tools are presented for a case study covering the redesign of the DO-228 with a hybrid-electric propulsion system in combination with the electrification of its systems architecture and different subsystem technologies.
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This paper proposes an adaptive fault-tolerant control allocation strategy to accommodate concurrent actuator faults for an over-actuated hybrid fixed-wing UAV. The proposed control strategy is divided into two modules by introduc...
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This paper proposes an adaptive fault-tolerant control allocation strategy to accommodate concurrent actuator faults for an over-actuated hybrid fixed-wing UAV. The proposed control strategy is divided into two modules by introducing an intermediate virtual control and control allocation. As a low-level control module, the control allocation scheme is used to distribute the virtual control signals among the available actuators while considering their position and rate limits. When actuator faults occur, there will be errors between the generated virtual control signals from the control allocation module and the desired one from the high-level control module. In this case, the proposed adaptive sliding mode control can seamlessly adjust the control parameters for the high-level control module and generate more virtual control signals to eliminate the adverse effect of actuator faults and maintain the overall system stability. The effectiveness and superiority of the proposed control strategy is demonstrated by simulation results in comparison with a nominal sliding mode control under both single and concurrent actuator fault conditions.
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