Journal articles on the topic 'Helicopter dynamic systems'
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Khalesi, Mohammad Hossein, Hassan Salarieh, and Mahmoud Saadat Foumani. "System identification and robust attitude control of an unmanned helicopter using novel low-cost flight control system." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 234, no. 5 (August 27, 2019): 634–45. http://dx.doi.org/10.1177/0959651819869718.
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In recent years, unmanned aerial systems have attracted great attention due to the electronic systems technology advancements. Among these vehicles, unmanned helicopters are more important because of their special abilities and superior performance. The complex nonlinear dynamic system (caused by main rotor flapping dynamics coupled with the rigid body rotational motion) and considerable effects of ambient disturbance make their utilization hard in actual missions. Attitude dynamics have the main role in helicopter stabilization, so implementing proper control system for attitude is an important issue for unmanned helicopter hovering and trajectory tracking performance. Besides this, experimental utilization of low-cost flight control system for unmanned helicopters is still a challenging task. In this article, dynamic modeling, system identification, and robust control system implementation of roll and pitch dynamics of an unmanned helicopter is performed. A TRex-600E radio-controlled helicopter is equipped with a novel low-cost flight control system designed and constructed based on Raspberry Pi Linux-based microcomputer. Using Raspberry Pi makes this platform simpler to utilize and more time and cost-effective than similar platforms used before. The experiments are performed on a 5-degree-of-freedom testbed. The robust control system is designed based on [Formula: see text] method and is evaluated in real flight tests. The experiment results show that the proposed platform has the ability to successfully control the roll and pitch dynamics of the unmanned helicopter.
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Fahimi, Farbod. "Full formation control for autonomous helicopter groups." Robotica 26, no. 2 (March 2008): 143–56. http://dx.doi.org/10.1017/s0263574707003670.
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SUMMARYThis paper reports the design of sliding-mode control laws for controlling multiple small-sized autonomous helicopters in arbitrary formations. Two control schemes, which are required for defining arbitrary three-dimensional formation meshes, are discussed. In the presented leader–follower formation control schemes, each helicopter only needs to receive motion information from at most two neighboring helicopters. A nonlinear six-degree-of-freedom dynamic model has been used for each helicopter. Four control inputs, the main and the tail rotor thrusts, and the roll and pitch moments, are assumed. Parameter uncertainty in the dynamic model and wind disturbance are considered in designing the controllers. The effectiveness and robustness of these control laws in the presence of parameter uncertainty in the dynamic model and wind disturbances are demonstrated by computer simulations.
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Abu Zarim, Mohamad Abu Ubaidah Amir, and Marja Azlima Omar. "Dynamic Mechanics of Rigid Helicopter Systems During Ditching." Transactions on Maritime Science 10, no. 2 (October 21, 2021): 439–47. http://dx.doi.org/10.7225/toms.v10.n02.013.
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Aircraft and helicopter often fly above open waters and thus have to observe regulations to ensure safe water landing under emergency conditions. This practice is also referred to as ditching - one of several types of slamming problems that are under review by the current regulations of the Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA). Ditching is related to the controlled landing on water, with distinctive features such as hydrodynamic slamming loads, complex hydromechanics at tremendous forward speeds, as well as the interaction of multiphase fluid dynamics (air, water, and vapor). This paper presents the knowledge on system mechanics during helicopter ditching. The discussion begins with the fundamental kinetics of the rigid body, and then delves into dynamic relations to describe the effect of forces on motions. In the end, the paper discusses several relevant theories to further contribute to the understanding of the problem of impact.
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Liu, Jianbo, Rongqiang Guan, Yongming Yao, Hui Wang, and Linqiang Hu. "A Novel Comprehensive Kinematic and Inverse Dynamic Model for the Flybar-Less Swashplate Mechanism: Application on a Small-Scale Unmanned Helicopter." Symmetry 12, no. 11 (November 9, 2020): 1849. http://dx.doi.org/10.3390/sym12111849.
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In this paper, we propose a novel kinematic and inverse dynamic model for the flybar-less (FBL) swashplate mechanism of a small-scale unmanned helicopter. The swashplate mechanism is an essential configuration of helicopter flight control systems. It is a complex, multi-loop chain mechanism that controls the main rotor. In recent years, the demand for compact swashplate designs has increased owing to the development of small-scale helicopters. The swashplate mechanism proposed in this paper is the latest architectures used for hingeless rotors without a Bell-Hiller mixer. Firstly, the kinematic analysis is derived from the parallel manipulators concepts. Then, based on the principle of virtual work, a methodology for deriving a closed-form dynamic equation of the FBL swashplate mechanism is developed. Finally, the correctness and efficiency of the presented analytical model are demonstrated by numerical examples and the influence factors of the loads acted on actuators are discussed.
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Gildish, Eli, Michael Grebshtein, Yehudit Aperstein, Alex Kushnirski, and Igor Makienko. "Helicopter Bolt Loosening Monitoring using Vibrations and Machine Learning." PHM Society European Conference 7, no. 1 (June 29, 2022): 146–55. http://dx.doi.org/10.36001/phme.2022.v7i1.3322.
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The existing helicopter Health and Usage Management Systems (HUMS) collect and process flight operational parameters and sensors data such as vibrations to provide health monitoring of the helicopter dynamic assemblies and engines. So far, structure-related mechanical faults, such as looseness in bolted structures, have not been addressed by vibration-based condition monitoring in existing HUMS systems. Bolt loosening was identified as a potential risk to flight safety demanding periodical visual monitoring, and increased maintenance and repair expenses. Its automatic identification in helicopters by using vibration measurements is challenging due to the limited number of known events and the presence of high-energy vibrations originating in rotating parts, which shadow the low-level signals generated by the bolt loosening.
New developed bolt loosening monitoring approach was tested on HUMS vibrations data recorded from the IAF AH-64 Apache helicopters fleet. ML-based unsupervised anomaly detection was utilized in order to address the limited number of faulty cases. The predictive power of health features was significantly improved by applying the Harmonic filtering differentiating between the high-energy vibrations generated by rotating parts compared with the low-energy structural vibrations. Different unsupervised anomaly detection techniques were examined on the dataset. The experimental results demonstrate that the developed approach enable successful bolt loosening monitoring in helicopters and can potentially be used in other health monitoring applications.
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Ma, Rui, Li Ding, and Hongtao Wu. "Dynamic Decoupling Control Optimization for a Small-Scale Unmanned Helicopter." Journal of Robotics 2018 (June 27, 2018): 1–12. http://dx.doi.org/10.1155/2018/9897684.
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This article presents design and optimization results from an implementation of a novel disturbance decoupling control strategy for a small-scale unmanned helicopter. Such a strategy is based on the active disturbance rejection control (ADRC) method. It offers an appealing alternative to existing control approaches for helicopters by combining decoupling and disturbance rejection without a detailed plant dynamics. The tuning of the control system is formulated as a function optimization problem to capture various design considerations. In comparison with several different iterative search algorithms, an artificial bee colony (ABC) algorithm is selected to obtain the optimal control parameters. For a fair comparison of control performance, a well-designed LQG controller is also optimized by the proposed method. Comparison results from an attitude tracking simulation against wind disturbance show the significant advantages of the proposed optimization control for this control application.
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Wang, Jialiang, Hai Zhao, Yuanguo Bi, Shiliang Shao, Qian Liu, Xingchi Chen, Ruofan Zeng, Yu Wang, and Le Ha. "An Improved Fast Flocking Algorithm with Obstacle Avoidance for Multiagent Dynamic Systems." Journal of Applied Mathematics 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/659805.
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Flocking behavior is a common phenomenon in nature, such as flocks of birds and groups of fish. In order to make the agents effectively avoid obstacles and fast form flocking towards the direction of destination point, this paper proposes a fast multiagent obstacle avoidance (FMOA) algorithm. FMOA is illustrated based on the status of whether the flocking has formed. If flocking has not formed, agents should avoid the obstacles toward the direction of target. If otherwise, these agents have reached the state of lattice and then these agents only need to avoid the obstacles and ignore the direction of target. The experimental results show that the proposed FMOA algorithm has better performance in terms of flocking path length. Furthermore, the proposed FMOA algorithm is applied to the formation flying of quad-rotor helicopters. Compared with other technologies to perform the localization of quad-rotor helicopter, this paper innovatively constructs a smart environment by deploying some wireless sensor network (WSN) nodes using the proposed localization algorithm. Finally, the proposed FMOA algorithm is used to conduct the formation flying of these quad-rotor helicopters in the smart environment.
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Bittanti, Sergio, Fabrizio Lorito, and Silvia Strada. "An LQ Approach to Active Control of Vibrations in Helicopters." Journal of Dynamic Systems, Measurement, and Control 118, no. 3 (September 1, 1996): 482–88. http://dx.doi.org/10.1115/1.2801171.
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In this paper, Linear Quadratic (LQ) optimal control concepts are applied for the active control of vibrations in helicopters. The study is based on an identified dynamic model of the rotor. The vibration effect is captured by suitably augmenting the state vector of the rotor model. Then, Kalman filtering concepts can be used to obtain a real-time estimate of the vibration, which is then fed back to form a suitable compensation signal. This design rationale is derived here starting from a rigorous problem position in an optimal control context. Among other things, this calls for a suitable definition of the performance index, of nonstandard type. The application of these ideas to a test helicopter, by means of computer simulations, shows good performances both in terms of disturbance rejection effectiveness and control effort limitation. The performance of the obtained controller is compared with the one achievable by the so called Higher Harmonic Control (HHC) approach, well known within the helicopter community.
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De Pratti, Giovanni Maria. "Airfoil to Improve Aerodynamic Performance OF Aileron Reduced Spanwise in Combat Helicopter." E3S Web of Conferences 197 (2020): 11003. http://dx.doi.org/10.1051/e3sconf/202019711003.
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Combat helicopters frequently operate in the part of Planetary Boundary Layer (PBL) characterised by the presence of dust and many other aggressive agents, particularly, in desertic areas and in marine sites, so the aerodynamic performance of their ailerons reduced spanwise, carrying out weapon systems, may be reduced within unacceptable values and consequent relevant risks for the stability of the copter. According to some experts, ailerons for weapon systems of helicopter are not involved in the global lift of the copter, but their operative function is only to carry the combat systems..Nevertheless, some crash occurred to US combat helicopters suggest a different point of view, and an aileron damage, perhaps due to a kind of dynamic stall phenomenon, seems have been caused the copter fall. These problems may be avoided using particularly airfoil for the section of aileron instead of classic ones as NACA four digit series (as 00120018). These profiles may be FFA-W1-XXX series, characterised by a double curvature of camber-line. In the present paper, after a deep analysis of operative conditions of modern combat helicopters, the aerodynamic performance of aileron section as NACA 0018 and FFA-W1-182 have been analysed and compared, and the results of tests carried out on a water table test bench are exposed and discusses.
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Guivarch, D., E. Mermoz, Y. Marino, and M. Sartor. "Creation of helicopter dynamic systems digital twin using multibody simulations." CIRP Annals 68, no. 1 (2019): 133–36. http://dx.doi.org/10.1016/j.cirp.2019.04.041.
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Beltran-Carbajal, Francisco, Hugo Yañez-Badillo, Ruben Tapia-Olvera, Antonio Favela-Contreras, Antonio Valderrabano-Gonzalez, and Irvin Lopez-Garcia. "On Active Vibration Absorption in Motion Control of a Quadrotor UAV." Mathematics 10, no. 2 (January 13, 2022): 235. http://dx.doi.org/10.3390/math10020235.
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Conventional dynamic vibration absorbers are physical control devices designed to be coupled to flexible mechanical structures to be protected against undesirable forced vibrations. In this article, an approach to extend the capabilities of forced vibration suppression of the dynamic vibration absorbers into desired motion trajectory tracking control algorithms for a four-rotor unmanned aerial vehicle (UAV) is introduced. Nevertheless, additional physical control devices for mechanical vibration absorption are unnecessary in the proposed motion profile reference tracking control design perspective. A new dynamic control design approach for efficient tracking of desired motion profiles as well as for simultaneous active harmonic vibration absorption for a quadrotor helicopter is then proposed. In contrast to other control design methods, the presented motion tracking control scheme is based on the synthesis of multiple virtual (nonphysical) dynamic vibration absorbers. The mathematical structure of these physical mechanical devices, known as dynamic vibration absorbers, is properly exploited and extended for control synthesis for underactuated multiple-input multiple-output four-rotor nonlinear aerial dynamic systems. In this fashion, additional capabilities of active suppression of vibrating forces and torques can be achieved in specified motion directions on four-rotor helicopters. Moreover, since the dynamic vibration absorbers are designed to be virtual, these can be directly tuned for diverse operating conditions. In the present study, it is thus demonstrated that the mathematical structure of physical mechanical vibration absorbers can be extended for the design of active vibration control schemes for desired motion trajectory tracking tasks on four-rotor aerial vehicles subjected to adverse harmonic disturbances. The effectiveness of the presented novel design perspective of virtual dynamic vibration absorption schemes is proved by analytical and numerical results. Several operating case studies to stress the advantages to extend the undesirable vibration attenuation capabilities of the dynamic vibration absorbers into trajectory tracking control algorithms for nonlinear four-rotor helicopter systems are presented.
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Shim, Sung Bo, Yeonghwan Bae, and Young Mo Koo. "Agility Comparison of Stabilizer and Direct Head Systems Mounted on an Unmanned Agricultural Helicopter." Transactions of the ASABE 61, no. 6 (2018): 1813–21. http://dx.doi.org/10.13031/trans.12650.
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Abstract. Recently, there has been increasing interest in using unmanned aerial vehicles (UAVs) to reduce the labor required for pest control and to protect farmers from exposure to pesticides. Unmanned aerial application has become a new paradigm in pesticide application; however, a uniform speed must be maintained within a short accelerating distance when spraying small plots, and this depends on the skill of the operator, which is difficult to rely on. In this study, the agility of a direct head system mounted on an unmanned agricultural helicopter was compared with that of a conventional stabilizer head system by using a pitch sweep test in CIFER, a dynamic analysis software program. The controllable frequency range of the unmanned agricultural helicopter with the direct head was analyzed to range between 0.06 and 5 Hz, and the responsiveness of the helicopter with the conventional stabilizer head was observed in a relatively low frequency range of 0.06 to 1.6 Hz. In addition, in comparing the equivalent time delay between the representative transfer functions from the pitch direction input to the surge acceleration obtained using NAVFIT analysis, the time delay of the direct head was shorter than that of the stabilizer head, although the extent of the enhancement was not satisfactory because of the tail gyroscope used for intrinsic attitude stability. Keywords: Agility, Agricultural unmanned helicopter, CIFER, Flight dynamics, Swash head system.
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Tatarchuk, T., Yu Kravchuk, and V. Pelukh. "ESTIMATION OF GAS-DYNAMIC PARAMETERS AT THE EXIT OF THE IMPELLER DURING MODERNIZATION OF MI-2MSB FAN INSTALLATION." Innovative Materials and Technologies in Metallurgy and Mechanical Engineering, no. 2 (January 9, 2023): 57–63. http://dx.doi.org/10.15588/1607-6885-2022-2-10.
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Purpose. Analysis of methods to increase the efficiency of the cooling system of theAI-450M engine units of the Mi-2MSB helicopter and evaluation of gas-dynamic parameters at the impeller outlet, fan installation MI-2MSB Research methods: finite element method (FEM). Results. It was shown that the use of a centrifugal fan as the main element in the system of air injection, cabin air conditioning and cooling systems and engine units provide the following opportunities and improvements: - at constant speeds and without changes in the transmission system to increase the amount of running air by 200…300 %; - reduce the temperature of heated units to the values recommended by the operation manual; - to increase the service life of complex-loaded elements of the system of connection of free turbine shafts with the shaft of the main gearbox; - reduce the risk of accidents due to poor air conditioning in the cockpit and passenger seats. The analysis of possible types of C.S modernization was carried out, the estimated estimation of gas-dynamic parameters at the exit of the impeller - to the sub-radiator space was carried out. The problem was solved by changing the type of impeller from axial to centrifugal. Scientific novelty. The problem of creating an efficient and reliable cooling system for internal systems and units of the Mi-2MSB light multi-purpose aircraft, which has been modernized with the replacement of old GTD-350 engines with newer ones, AI-450 series - urgent, in the absence of similar light helicopters of domestic production. An important component of the safety and reliability of all components of the helicopter is to maintain the correct thermal regime of its components. Practical value. The obtained results are important in the further process of production and modernization of the Mi-2 helicopter of all modifications with the latest engines, as well as for helicopter development projects in Ukraine - SME-2 “Hope”, SME-6 “Otaman”, SME-8 and others. The ability to increase cooling efficiency, air conditioning and reduce engine load increases the life, reliability of components and improves comfort and performance for pilots and passengers.
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Castillo-Rivera, Salvador, and Maria Tomas-Rodriguez. "Description of a Dynamical Framework to Analyse the Helicopter Tail Rotor." Dynamics 1, no. 2 (October 12, 2021): 171–80. http://dx.doi.org/10.3390/dynamics1020010.
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In this work, a tail rotor is modelled with the aid of a multibody software to provide an alternative tool in the field of helicopter research. This advanced application captures the complex behaviour of tail rotor dynamics. The model has been built by using VehicleSim software (Version 1.0, Mechanical Simulation Corporation, Ann Arbor, MI, USA) specialized in modelling mechanical systems composed of rigid bodies. The dynamic behaviour and the control action are embedded in the code. Thereby, VehicleSim does not need an external link to another software package. The rotors are articulated, the tail rotor considers flap and feather degrees of freedom for each of the equispaced blades and their dynamic couplings. Details on the model’s implementation are derived, emphasising the modelling aspects that contribute to the coupled dynamics. The obtained results are contrasted with theoretical approaches and these have displayed to agree with the expected behaviour. This rotorcraft model helps to study the performance of a tail rotor under certain dynamic conditions.
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HU, Guo-cai, Jin-wu XIANG, and Xiao-gu ZHANG. "Dynamic Stability Analysis for Helicopter Rotor/Fusel age Coupled Nonlinear Systems." Chinese Journal of Aeronautics 16, no. 1 (February 2003): 22–28. http://dx.doi.org/10.1016/s1000-9361(11)60166-0.
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Enns, Russell, and Jennie Si. "Apache Helicopter Stabilization Using Neural Dynamic Programming." Journal of Guidance, Control, and Dynamics 25, no. 1 (January 2002): 19–25. http://dx.doi.org/10.2514/2.4870.
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Azzam, H., and M. Andrew. "A Modular Intelligent Data Administration Approach for Helicopter Health and Usage Monitoring Systems." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 209, no. 2 (April 1995): 139–45. http://dx.doi.org/10.1243/pime_proc_1995_209_280_02.
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Much effort and expenditure has been focused on the introduction of acquisition and processing hardware for helicopter health and usage monitoring systems (HUMS) operations. In contrast, the potential difficulties in the management of HUMS data have received much less attention. HUMS hardware will typically generate in excess of one megabyte of data per flight. This data will be downloaded to ground station computers for further analysis. A modular intelligent data administration system (MIDAS) is highly desirable in order to efficiently extract useful information from the huge amount of HUMS data, and provide general robust diagnostic strategies. A state-of-the-art implementation of relevant technologies and analysis methods is essential to realize such a system. This paper presents the requirements and structure of MIDAS and details an approach that integrates neural network technology, helicopter mathematical dynamic models and unsupervised pattern recognition techniques. Examples using vibration and spectrometric oil analysis programmes (SOAP) as a means to evaluate the health and usage of helicopter components are presented.
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Pavel, Marilena D., Perumal Shanthakumaran, Qiping Chu, Olaf Stroosma, Mike Wolfe, and Harm Cazemier. "Incremental Nonlinear Dynamic Inversion for the Apache AH-64 Helicopter Control." Journal of the American Helicopter Society 65, no. 2 (April 1, 2020): 1–16. http://dx.doi.org/10.4050/jahs.65.022006.
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Incremental nonlinear dynamic inversion (INDI)-based controller is a promising technique that can be adopted to control dynamic systems with high nonlinearities and extended cross-coupling effects. This paper presents the incremental strategy adopted as a sensor-based controller approach for the Apache AH-64D Longbow helicopter. The strength of the INDI sensor– based approach is that it does not require a detailed vehicle model as it uses only a control effectiveness model and estimates of the vehicle angular accelerations replacing the rest of the model. The weakness is its sensitivity to measurement and actuator delays, demanding additional estimations of model parameters and control effectiveness tuning. Using the Boeing FLYRT Apache model to simulate the vehicle dynamics, the paper has developed three adaptation schemes connecting the INDI sensor–based approach to the Apache partial control authority set as ±20% authority in all axes. The goal was to redesign the existing Apache's flight control systems and demonstrate handling qualities improvements for hover and low-speed flight in normal and degraded visual environment. Implementing the attitude command attitude hold and translational rate command response types in the system through the INDI controller, the paper demonstrates that improvements from Level 2 to Level 1 handling qualities can be achieved when flying the Aeronautical Design Standard-33 (ADS-33E-PRF) hover and pirouette maneuvers in a degraded visual environment.
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Sheppard, Daniel J., Joyce Madden, and Sherrie A. Jones. "Simulator Design Features for Helicopter Shipboard Landings." Proceedings of the Human Factors Society Annual Meeting 31, no. 2 (September 1987): 233–37. http://dx.doi.org/10.1177/154193128703100222.
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The Vertical Takeoff and Landing Simulator (VTOL) at the Naval Training Systems Center's (NTSC) Visual Technology Research Simulator (VTRS) was used to study the effects of simulator design features on pilot performance in helicopter shipboard landings. The research was designed to evaluate the effects of current design features on the SH—60B Operational Flight Trainer (OFT) used to train helicopter shipboard landing and four proposed simulator design modifications. These were: (1) scene detail (SH—60B OFT scene versus an upgraded VTRS scene), (2) field-of-view (VTRS wide versus a smaller SH—60B OFT field-of-view), (3) dynamic seat cueing (on versus off), and (4) dynamic inflow (standard rotor model available in existing trainers versus an updated rotor model). These factors were tested across two levels of seastate. On the basis of the factors studied in the experiment, the wider field-of-view, the more detailed scene and the updated rotor model are recommended for use. The dynamic seat cueing evaluated in this study is not recommended at this time.
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Fei, Zhongyang, and David A. Peters. "Modal analysis of finite-state dynamic inflow for rotary wing systems." Journal of Vibration and Control 23, no. 7 (October 3, 2016): 1086–94. http://dx.doi.org/10.1177/1077546315588396.
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In this paper, the finite-state helicopter rotor inflow modes have been studied based on eigenanalysis. The inflow velocity mode shapes with node lines have been displayed with various skew angles. The eigenvalues are highly coupled especially for higher skew angles, and the mode shapes change significantly for different angles. The changing of eigenvalues with different harmonic numbers is also exhibited in the tables for axial flow of both the Peters–He and Morillo dynamic inflow models. An easy way to estimate the eigenvalues of the Peters–He inflow model is also established.
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Xu, Yong Cheng, Bin Dong, Yue Li, Guo Ji Shen, and Ming Lei Luo. "Reliability Modeling and Availability Simulating Based on GSPN Considering Hardware, Software and Human Factors." Advanced Materials Research 834-836 (October 2013): 1932–37. http://dx.doi.org/10.4028/www.scientific.net/amr.834-836.1932.
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Aiming at the functional and structural characteristics of helicopter power transmission systems, this paper researches on the dynamic reliability modeling and simulating methods of complex mechanical systems. The hardware reliability, the human reliability and the software reliability related to helicopter power transmission systems are analyzed in this paper from the view point of systems engineering; the General Stochastic Petri Nets (GSPN) reliability models are established and the availability is simulated. According to the logistic connection among the attributions of the systems availability, two conceptions are presented: degree of facilitation and a new availability calculation model. Results show that the calculational value is very close to the simulating value. The new model based on facilitation is proved to be correct. The paper contributes to provide an effective reliability analyzing method and theoretical basis for complex mechanical system.
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Zuñiga, Manuel A., Luis A. Ramírez, Gerardo Romero, Efraín Alcorta-García, and Alejandro Arceo. "Passive Fault-Tolerant Control of a 2-DOF Robotic Helicopter." Information 12, no. 11 (October 27, 2021): 445. http://dx.doi.org/10.3390/info12110445.
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The presence of faults in dynamic systems causes the potential loss of some of the control objectives. For that reason, a fault-tolerant controller is required to ensure a proper operation, as well as to reduce the risk of accidents. The present work proposes a passive fault-tolerant controller that is based on robust techniques, which are utilized to adjust a proportional-derivative scheme through a linear matrix inequality. In addition, a nonlinear term is included to improve the accuracy of the control task. The proposed methodology is implemented in the control of a two degrees of a freedom robotic helicopter in a simulation environment, where abrupt faults in the actuators are considered. Finally, the proposed scheme is also tested experimentally in the Quanser® 2-DOF Helicopter, highlighting the effectiveness of the proposed controller.
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Pei, Yang, Qiang Dong, Ting Guo, and Bi Feng Song. "Automotive Route Planning Method for Minimizing the Radar Detection of an Armed Helicopter." Applied Mechanics and Materials 55-57 (May 2011): 1541–46. http://dx.doi.org/10.4028/www.scientific.net/amm.55-57.1541.
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Radar systems are used by air defense forces to detect and track aircraft. Route planning attempts to enhance safety by minimizing the exposure of the aircraft to the threat air defense systems while achieving the mission objectives. Based on Voronoi diagram theory, a flight route optimization method is introduced to insure the armed helicopter to penetrate the emery’s radar defense system at the lowest danger. The factors, such as radar cross section and distance between helicopter and radar, that affect the radar detection are firstly analyzed. Then Voronoi diagram and its application for route planning to minimize the detection probability of an armed helicopter are described introduced in details. Dijkstra algorithm is employed to solve the optimization problem and to obtain the initial flight path. The simulation of artificial potential field dynamic is performed to transform the initial path to the smooth flight route. Example analysis of a hypothesis armed helicopter shows that the developed method is helpful for the on-the-spot planning that combines aircraft flight performance and intelligence information regarding the estimated enemy weapon locations to develop routes that avoid or mask the enemy sensor and weapon envelopes.
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Haviland, Stephen, Dmitry N. Bershadsky, and Eric N. Johnson. "Rapid Automatic Slung Load Operations with Unmanned Helicopters." Journal of the American Helicopter Society 64, no. 4 (October 1, 2019): 1–11. http://dx.doi.org/10.4050/jahs.64.042009.
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Slung load operations often involve following conservative flight paths to prevent unwanted swing of the load. However, doing so often limits the maneuvering capability of the system and increases the time to complete trajectories. This work investigates methods to rapidly move a slung load with a helicopter with the intent to deliver it quickly and precisely to a fixed point. Inspired by prior work utilizing differential flatness, which is a property of certain systems that allow for advantageous controllers to be developed for nonlinear systems, the controller developed does not require instrumentation of the load or the ability to estimate the state of the load but does not preclude it. A feedforward and feedback controller was developed that modifies the helicopter commands based on the desired load path. The controller is simplified by neglecting selected higher order terms and modeling the load as a point-mass. An adaptive dynamic inversion controller is used to control the helicopter. A fixed downward-facing camera is used to provide estimates of load position for the feedback controller. Simulation and flight-test results are shown using a Yamaha R-MAX helicopter to validate the proposed method.
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Azzam, H., and M. J. Andrew. "The use of Math-Dynamic Models to Aid the Development of Integrated Health and Usage Monitoring Systems." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 206, no. 1 (January 1992): 71–76. http://dx.doi.org/10.1243/pime_proc_1992_206_240_02.
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Development of integrated health and usage monitoring systems (IHUMS) involved the use of personal computer-based math-dynamic models, which in this particular case simulate a range of helicopter rotor system faults and potentially catastrophic failures. Using both theoretical and in-field data, over 120 fault cases have been analysed to identify discriminatory characteristics. This paper reports on the background of the math-dynamic models and the findings of the diagnostic analysis.
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Sajjadi, Sina, Mehran Mehrandezh, and Farrokh Janabi-Sharifi. "A Cascaded and Adaptive Visual Predictive Control Approach for Real-Time Dynamic Visual Servoing." Drones 6, no. 5 (May 14, 2022): 127. http://dx.doi.org/10.3390/drones6050127.
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In the past two decades, Unmanned Aerial Vehicles (UAVs) have gained attention in applications such as industrial inspection, search and rescue, mapping, and environment monitoring. However, the autonomous navigation capability of UAVs is aggravated in GPS-deprived areas such as indoors. As a result, vision-based control and guidance methods are sought. In this paper, a vision-based target-tracking problem is formulated in the form of a cascaded adaptive nonlinear Model Predictive Control (MPC) strategy. The proposed algorithm takes the kinematics/dynamics of the system, as well as physical and image constraints into consideration. An Extended Kalman Filter (EKF) is designed to estimate uncertain and/or time-varying parameters of the model. The control space is first divided into low and high levels, and then, they are parameterised via orthonormal basis network functions, which makes the optimisation- based control scheme computationally less expensive, therefore suitable for real-time implementation. A 2-DoF model helicopter, with a coupled nonlinear pitch/yaw dynamics, equipped with a front-looking monocular camera, was utilised for hypothesis testing and evaluation via experiments. Simulated and experimental results show that the proposed method allows the model helicopter to servo toward the target efficiently in real-time while taking kinematic and dynamic constraints into account. The simulation and experimental results are in good agreement and promising.
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Padfield, Gareth D. "The making of helicopter flying qualities: a requirements perspective." Aeronautical Journal 102, no. 1018 (December 1998): 409–37. http://dx.doi.org/10.1017/s0001924000027627.
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AbstractIn this review paper, a recurring theme is the interplay between flying qualities as a technical discipline and flying qualities as an operational attribute. This interplay provides the setting for a presentation on the status of helicopter flying quahties, using maritime helicopter operations as the focus, particularly the recovery phase and the helicopter-ship dynamic interface. Poor weather, inducing high sea states and ship motion, along with complex, invisible and disturbing airflow and degraded visibility, make the dynamic interface a particularly demanding environment for both pilot and helicopter.Flying qualities are a product of four elements — the aircraft, the pilot, the task and the environment — and the maritime application serves to give this viewpoint its full perspective. Mission-oriented flying quahties engineering is described within the systems framework of Aeronautical Design Standard 33 (ADS-33), utilising concepts like the mission task element, usable cue environment, response type and dynamic response criteria. The innovative constructs introduced by ADS-33 for flying qualities in degraded visual conditions are given special attention. The paper argues that the requirements for what constitutes safe and easy, or Level 1, flying qualities now exist and are well substantiated. New aircraft can now be designed to achieve these performance and safety standards while existing aircraft can be upgraded with integrated flight management systems featuring advanced control/flying qualities technologies.In this context, the paper also promotes the concept of concurrent requirements capture and preliminary design, to maximise the likelihood that user requirements are achieved and that designs are robust and work first time. The multidisciplinary nature of flying qualities is emphasised, embracing aeromechanics and flight dynamics, controls and displays and human factors. Similarly, the importance of high-fidelity design tools and comprehensive evaluation methods in the concurrent process is stressed.Handling deficiencies can increase the risk of helicopter accidents, particularly in degraded visual conditions or in emergencies where excursions beyond the operational flight envelope can lead to piloting difficulties. These situations are the new challenges for flying qualities engineers, and two areas are discussed here in some detail. First, flight in severely degraded visual conditions, highlighting the importance of understanding the fundamentals of human visual perception in the development of integrated control and display augmentation. Second, handling qualities following tail rotor failures are discussed and results from current research to develop new advice for aircrew are presented. The author takes the view that much more can and needs to be done to assist the pilot in the management of the tension between performance and safety in helicopter operations, through the provision of improved flying qualities.
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Wang, Fei, Peidong Liu, Shiyu Zhao, Ben M. Chen, Swee King Phang, Shupeng Lai, Tao Pang, Biao Wang, Chenxiao Cai, and Tong H. Lee. "Development of an Unmanned Helicopter for Vertical Replenishment." Unmanned Systems 03, no. 01 (January 2015): 63–87. http://dx.doi.org/10.1142/s2301385015500053.
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This paper presents an intelligent and robust guidance, navigation and control solution for a rotary-wing UAV to carry out an autonomous cargo transportation mission between two moving platforms. Different from the conventional GPS/INS-only navigation scheme, this solution also integrates sophisticated Lidar and vision systems capable of precisely locating cargo loading and unloading positions. Besides, another complementary GPS/INS system is set up on the moving platforms with communication to the unmanned helicopter so that the controlled UAV is able to follow the dynamic platforms with good tracking performance. The whole system has been successfully implemented, and with its superb performance the Unmanned Systems Research Group from the National University of Singapore won the first place in the final round of the rotary-wing category competition of the 2nd AVIC Cup — International UAV Innovation Grand Prix 2013.
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Panteleev, Andrei, and Aleksandra Yakovleva. "Approximate methods of H-infinity control of nonlinear dynamic systems output." MATEC Web of Conferences 362 (2022): 01021. http://dx.doi.org/10.1051/matecconf/202236201021.
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The problem of finding H∞-regulators in the output control problem is considered. Two approaches for approximate synthesis of the closed loop systems are proposed. The paper considers the problem of finding the H-infinity control of a nonlinear continuous dynamical system output. The system is linear in control and perturbation, with a finite time of the system operation. Methods for finding H-infinity control are used to solve problems of synthesis of controllers, particularly for solving the problem of synthesis of controllers in conditions of incomplete state information. In such problems, it is difficult to find the structure of the regulator and its parameters. Sufficient H∞-control conditions are formulated and proved. Two approximate methods for finding the H-infinity controller of closed loop nonlinear continuous systems were proposed. To illustrate the application of the methods, the problem of stabilization of the ZD559-Lynx helicopter, whose flight takes place during the imposed time period of the system operation, was considered.
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Sinha, S. C., Der-Ho Wu, V. Juneja, and P. Joseph. "Analysis of Dynamic Systems With Periodically Varying Parameters Via Chebyshev Polynomials." Journal of Vibration and Acoustics 115, no. 1 (January 1, 1993): 96–102. http://dx.doi.org/10.1115/1.2930321.
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In this paper a general method for the analysis of multidimensional second-order dynamic systems with periodically varying parameters is presented. The state vector and the periodic matrices appearing in the equations are expanded in Chebyshev polynomials over the principal period and the original differential problem is reduced to a set of linear algebraic equations. The technique is suitable for constructing either numerical or approximate analytical solutions. As an illustrative example, approximate analytical expressions for the Floquet characteristic exponents of Mathieu’s equation are obtained. Stability charts are drawn to compare the results of the proposed method with those obtained by Runge-Kutta and perturbation methods. Numerical solutions for the flap-lag motion of a three-bladed helicopter rotor are constructed in the next example. The numerical accuracy and efficiency of the proposed technique is compared with standard numerical codes based on Runge-Kutta, Adams-Moulton, and Gear algorithms. The results obtained in both the examples indicate that the suggested approach is extremely accurate and is by far the most efficient one.
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Fusato, Dario, and Roberto Celi. "Design Sensitivity Analysis for Helicopter Flight Dynamic and Aeromechanic Stability." Journal of Guidance, Control, and Dynamics 26, no. 6 (November 2003): 918–27. http://dx.doi.org/10.2514/2.6919.
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Liu, Qian, Zhuxin Zhang, Tuo Jia, Lixin Wang, and Dingxuan Zhao. "Energy Consumption Analysis of Helicopter Traction Device: A Modeling Method Considering Both Dynamic and Energy Consumption Characteristics of Mechanical Systems." Energies 15, no. 20 (October 20, 2022): 7772. http://dx.doi.org/10.3390/en15207772.
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Since modern times, the increase in shipborne equipment has brought tremendous pressure to the energy supply system. Establishing an accurate and reliable energy consumption model that reflects the dynamic characteristics of the system will provide an essential theoretical reference for energy efficiency optimization. This paper proposes a modeling method that considers both the dynamic characteristics and energy consumption characteristics of the system, based on the power bond-graph theory. Firstly, the transmission principle and energy transfer process of hydraulic and electric helicopter traction devices are analyzed. Then, the energy consumption is analyzed, and the state equation and energy equation of the system are established. Finally, the simulation tests are carried out. The results show that the proposed dynamic modeling method is reasonable and effective and can well reflect the dynamic characteristics and energy consumption characteristics of the system.
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Boubakir, Ahsene, Salim Labiod, Fares Boudjema, and Franck Plestan. "Design and experimentation of a self-tuning PID control applied to the 3DOF helicopter." Archives of Control Sciences 23, no. 3 (September 1, 2013): 311–31. http://dx.doi.org/10.2478/acsc-2013-0019.
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Abstract The paper presents design and experimental validation of a stable self-tuning PID controller for three degrees of freedom (3-DOF) helicopter. At first, it is proposed a self-tuned proportional-integral-derivative (PID) controller for a class of uncertain second order multiinput multi-output nonlinear dynamic systems to which the 3-DOF helicopter dynamic model belongs. Within this scheme, the PID controller is employed to approximate unknown ideal controller that can achieve control objectives. PID controller gains are the adjustable parameters and they are updated online with a stable adaptation mechanism designed to minimize the error between the unknown ideal controller and the used by PID controller. The stability analysis of the closed-loop system is performed using Lyapunov approach. It is proven that all signals in the closed-loop system are uniformly ultimately bounded. The proposed approach can be regarded as a simple and effective model-free control since the mathematical model of the system is assumed unknown. Experimental results are presented to verify the effectiveness of the proposed controller.
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Bertucci, Alessandro, Andrea Mornacchi, Giovanni Jacazio, and Massimo Sorli. "A Force Control Test Rig for the Dynamic Characterization of Helicopter Primary Flight Control Systems." Procedia Engineering 106 (2015): 71–82. http://dx.doi.org/10.1016/j.proeng.2015.06.010.
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Xuejun, Li, Jiang Lingli, Hua Dengrong, Yin Daoxuan, and Yang Dalian. "An Analysis of the Gear Meshing Characteristics of the Main Planetary Gear Trains of Helicopters Undergoing Shafting Position Changes." International Journal of Aerospace Engineering 2021 (July 30, 2021): 1–12. http://dx.doi.org/10.1155/2021/9965818.
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The complex three-shaft three-reducer structural designs of helicopter transmission systems are prone to changes in the relative positions of shafting under the conditions of main rotor and tail rotor loads. These changes will affect the transmission characteristics of the entire transmission system. In this study, the planetary gear trains of helicopters were examined. Due to the fact that these structures are considered to be the most representative structures of the main reducers of helicopters, they were selected as the study objects for the purpose of examining the meshing characteristics of planetary gear trains when the relative positions of the shafting changed due to the position changes of the main rotor shafts under variable load conditions. It was found that by embedding the comprehensive time-varying meshing stiffness values of the main rotor shafts at different positions, a dynamic model of the relative position changes of the planetary gear trains could be established. Then, combined with the multibody dynamics software, the meshing characteristics of the sun gears, and the planetary gears, the planetary gears and the inner ring gears were simulated and analyzed under different inclinations and offsets of the shafting. The results obtained in this study revealed the following: (1) the average meshing force of the gears increased with the increases in the angle inclinations, and the meshing force between the sun gears and the planetary gears increased faster than the meshing force between the planetary gears and the inner ring gears. It was observed that during the changes in the shafting tilt positions, obvious side frequency signals had appeared around the peak of the meshing frequency in the spectrum. Then, with the continuous increases in the tilt position, the peak was gradually submerged; (2) the average meshing force of the gears increased with the increases in the offset, and the increasing trend of the meshing force between the sun gears and the planetary gears was similar to that observed between the planetary gears and the inner ring gears. It was found that when the shafting offset position changed, there were obvious first and second frequency doubling in the spectrum; (3) the mass center orbit radii of the sun gears increased with the increases in the shafting position changes, and the changes in the angular tilt position were found to have greater influencing effects on the mass center orbit radii of the sun gears than the changes in the offset positions. This study’s research findings will provide a theoretical basis for future operational status monitoring of the main transmission systems of helicopters and are of major significance for improvements in the operational stability of helicopter transmission systems, which will potentially ensure safe and efficient operations.
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Wzorek, Mariusz, Jonas Kvarnström, and Patrick Doherty. "Choosing Path Replanning Strategies for Unmanned Aircraft Systems." Proceedings of the International Conference on Automated Planning and Scheduling 20 (May 25, 2021): 193–200. http://dx.doi.org/10.1609/icaps.v20i1.13405.
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Unmanned aircraft systems use a variety of techniques to plan collision-free flight paths given a map of obstacles and no-fly zones. However, maps are not perfect and obstacles may change over time or be detected during flight, which may invalidate paths that the aircraft is already following. Thus, dynamic in-flight replanning is required. Numerous strategies can be used for replanning, where the time requirements and the plan quality associated with each strategy depend on the environment around the original flight path. In this paper, we investigate the use of machine learning techniques, in particular support vector machines, to choose the best possible replanning strategy depending on the amount of time available. The system has been implemented, integrated and tested in hardware-in-the-loop simulation with a Yamaha RMAX helicopter platform.
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Huang, Kang, Chao Ma, Han Zhao, and Zicheng Zhu. "Robust Control of Electric Tail Reduction System: Uncertainty and Performance Index." Applied Sciences 11, no. 1 (December 29, 2020): 260. http://dx.doi.org/10.3390/app11010260.
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The electric tail reduction system of the unmanned helicopter contains uncertainty. To solve this problem, a constraint-following approach was applied to design a novel robust control for uncertain mechanical systems. The dynamic model of the uncertain electric tail reduction system was established by combining the load of the electric tail rotor and the flight state of the helicopter. Based on the Udwadia–Kalaba theory, a robust constraint following the control method was proposed to deal with the uncertainty of the system. In addition, to balance the steady-state performance and control cost of the system, a control parameter optimization design method was proposed to minimize the performance index. Furthermore, the unique solution of the optimal parameter can be obtained. Compared with the LQR control method, the effectiveness of the optimization method of robust constraint following control was verified.
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Bradley, R., C. A. Macdonald, and T. W. Buggy. "Quantification and Prediction of Pilot Workload in the Helicopter/Ship Dynamic Interface." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 219, no. 5 (May 1, 2005): 429–43. http://dx.doi.org/10.1243/095441005x33376.
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The evaluation, early in the design cycle, of the limits for operating aircraft from ships in a wide range of sea states and atmospheric conditions has become an important issue for two main reasons. First, the simultaneous entry into service of new helicopter types and new naval platforms has generated an enormous task in the development of appropriate Ship Helicopter Operating Limits for in-service operations. Second, it has become clear that such operational factors need to be addressed at the design stage - which of necessity involves developing a predictive capacity in all of the areas which influence operational capability. These considerations need to take place in the context of technological advances which seek to assist the pilot in operations from ships. Improved radar for ship approaches and enhanced cueing, located around hangars and landing spots, are both areas which are being continually developed in association with upgraded aircraft systems for guidance, control, and stability augmentation. Ultimately, however, the situation comes down to the pilot's assessment of the workload involved in any task and the handling qualities of the vehicle being controlled. For this reason there has been a growing interest in two related areas: (i) the development of metrics to provide a consistent indicator of pilot workload and (ii) the enhancement of existing pilot models to generate authentic control activity in the aircraft/ship dynamic interface. This article describes recent techniques for extracting workload metrics from control activity and indicates the extent to which acceptably accurate workload predictions can be made. Some advances in pilot modelling are also described and examples are given to demonstrate the capability and limitations of currently available methods. Finally, the present state of integration of the two aspects into a robust tool for ship and aircraft system design is discussed. The focus of this article is, of necessity, on helicopter operations because that is where most of the current work has been centred.
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Li, Miaomiao, Jian Chen, Rupeng Zhu, Cheng Duan, Shuai Wang, and Xiong Lu. "Dynamic Stiffness and Damping Characteristics of a Shaft Damping Ring: A Combined Hyperelastic and Viscoelastic Constitutive Model." Shock and Vibration 2020 (October 5, 2020): 1–13. http://dx.doi.org/10.1155/2020/8822760.
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At higher velocities, the helicopter tail transmission system encounters notable difficulties due to excessive bending vibrations. The shaft damping ring installed on the shaft system was shown to effectively suppress the shaft system vibrations. In this paper, the dynamic stiffness and damping characteristics of polyurethane shaft damping rings were studied using hyperelastic and viscoelastic constitutive models. The constitutive model and the damping ring material parameters were determined using uniaxial tensile and double-shear frequency scanning tests. Based on the test results, the dynamic damping ring characteristics were simulated and verified by dynamic stiffness tests; the influence of structural parameters and operating conditions on the dynamic stiffness and damping characteristics of the damping ring were obtained. The results provide a theoretical basis for the design of shaft systems with reduced sensitivity to vibrations.
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Szelmanowski, Andrzej, Mariusz Zieja, and Krzysztof Głyda. "Dynamic Properties Modeling of the Thermoelectric Fire Sensors in the Aircraft Fire Suppression System." Journal of KONBiN 44, no. 1 (December 1, 2017): 293–307. http://dx.doi.org/10.1515/jok-2017-0074.
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Abstract The paper presents selected results of work at the Air Force Institute of Technology (AFIT) in the concerning modeling the dynamic properties of fire detectors used in aviation fire protection systems. In order to determine the conditions of false fire signals, the simulation models of thermoelectric fire detectors have been developed. Simulation models were tested in Matlab-Simulink computational packages for various methods of heating and cooling the sensors (among others, changes in ambient air temperature of the sensor, caused by the EWU exhaust gas diffusers were simulated – these diffusers are used to distribute flue gases from helicopter engines).
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Hoshu, Ayaz Ahmed, Liuping Wang, Shahzeb Ansari, Abdul Sattar, and Manzoor Hyder Alias Bilal. "System Identification of Heterogeneous Multirotor Unmanned Aerial Vehicle." Drones 6, no. 10 (October 20, 2022): 309. http://dx.doi.org/10.3390/drones6100309.
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An energy efficient heterogeneous multirotor unmanned aerial system (UAS) is presented in this paper, wherein, the aerodynamical characteristics of both helicopter and quadrotor are obtained in a single multirotor design. It features the energy efficiency and endurance of a helicopter, while keeping the mechanical simplicity, control and maneuverability of a quadrotor; employing a single large central rotor to get majority of the lift and four small arm canted rotors for control. Developing the stable and robust control strategy requires the accurate model of system. Due to the added mechanical complexities of the new design including the existence of couplings and gyroscopics, the modelling through the dynamic equations of the multirotor would not be possible in providing accurate results. Therefore, precise system modelling is required for the development of stable and robust control strategy. This paper proposes a novel system identification method with the objective to experimentally estimation of the precise dynamic model of the heterogeneous multirotor. The approach comprises of the utilization of input excitation signals, frequency sampling filter and derivation of transfer functions through complex curve fitting method. To validate the accuracy of the obtained transfer functions, the experimentally auto-tuned PID controllers are implemented over the transfer functions. Custom designed fight controller is used to experimentally implement the proposed idea. Presented results demonstrate the efficacy of the proposed approach for heterogeneous multirotor UAS.
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Zubov, N. E., and V. N. Ryabchenko. "Lateral Motion Control Invariance Helicopter on the Roll Angle. Analytical Synthesis." Mekhatronika, Avtomatizatsiya, Upravlenie 22, no. 6 (June 5, 2021): 331–36. http://dx.doi.org/10.17587/mau.22.331-336.
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For the linearized fourth-order model of the isolated lateral motion of a single-rotor helicopter as a MIMO system containing two inputs, the control is analytically synthesized, which ensures the invariance of the roll angle motion in the presence of disturbances in the control channels, as well as the required placement of the poles of the closed-loop system, given any specific values from the area of their stability. The approach to the synthesis of invariant control consists in finding a matrix of feedback coefficients of a linear system that satisfies the invariance conditions, which are a system of power matrix equations of a certain design. The synthesis is based on the application of theor ems based on the use of the regularization condition of the matrix equation and the invariance conditions under disturbances in the control channels, as well as theorems that make it possible to place the poles of the MIMO system using the original decomposition of the control object. Regularization of a matrix equation is understood as a solution to the problem of providing a given set of singular values for an inverted symmetric square matrix. The invariance of the MIMO system is considered with respect to unmeasured disturbances inthe control channels. The use of such an approach to the synthesis of invariant control made it possible to obtain an analytical solution that is versatile and can be applied in various flight modes of single-rotor helicopters with different dynamic properties. The results of the numerical synthesis of the lateral motion of a singlerotor helicopter using the obtained laws of invariant control, which confirm the reliability of the analytical expressions, areshown.
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Kada, B., K. A. T. Juhany, and A. S. A. Balamesh. "Hybrid high-order sliding mode-based control for multivariable cross-coupling systems: Scale-laboratory helicopter system application." Aeronautical Journal 121, no. 1243 (June 27, 2017): 1319–41. http://dx.doi.org/10.1017/aer.2017.57.
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ABSTRACTThis paper presents a high-order sliding mode approach to design variable structure controllers for nonlinear multivariable cross-coupling systems whereby a change in either control input affects the control loops of all the subsystems dynamics. A hybrid-sliding mode control (hybrid-SMC) scheme is constructed combining a new equivalent control algorithm with a high-order discontinuous control algorithm to benefit from the advantages of both control strategies. The hybrid-SMC scheme uses weighting coefficients to weight and combine controllers. The equivalent control algorithm uses a relative degree concept through dynamic constraints imposed on the sliding variables to overcome the limitations of the conventional approaches and to provide an optimum tracking performance. A scale-laboratory helicopter model is used to sum up the main features and demonstrate the effectiveness of the developed control scheme. The proposed hybrid-SMC strategy is compared to existing sliding mode-based control approaches in terms of tracking performance, stability and control efforts. The obtained results demonstrate the validity and efficiency of the proposed hybrid-SMC scheme.
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Yang, Da Lin, Wei Dong Yang, and Zhu Zhang. "Online Adaptive Fuzzy Neural Identification of a Piezoelectric Tube Actuator System." Applied Mechanics and Materials 275-277 (January 2013): 915–24. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.915.
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A coupled actuator-flap-circuit system model and its online identification are presented. The coupled system consists of a piezoelectric tube actuator, a trailing-edge flap, and a series R-L-C circuit. The properties of the coupled system are examined using a Mach-scaled rotor simulation on hovering state. According to the high nonlinear hysteretic characteristics of the coupled system, the generalized dynamic fuzzy neural networks (GD-FNN) implementing Takagi-Sugeno-Kang (TSK) fuzzy systems based on extended ellipsoidal radial basis function (EBF) neural network is used to identify the coupled system. The structures and parameters are adaptive adjusted during the learning process, and don’t need too much expert experiences. Simulation studies show that the piezoelectric tube actuator has high authority with a broad frequency bandwidth, satisfies the requirements for helicopter vibration reduction; GD-FNN has a high learning speed, the final networks have a parsimonious network structure and generalize well, possessing broad application prospects in the helicopter vibration reduction.
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Asiri, S., A. Baz, and D. Pines. "Periodic Struts for Gearbox Support System." Journal of Vibration and Control 11, no. 6 (June 2005): 709–21. http://dx.doi.org/10.1177/1077546305052784.
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Passive periodic structures exhibit unique dynamic characteristics that make them act as mechanical filters for wave propagation. As a result, waves can propagate along the periodic structures only within specific frequency bands called “pass bands” and wave propagation is completely blocked within other frequency bands called “stop bands”. In this paper, the emphasis is placed on developing a new class of these periodic structures called passive periodic struts, which can be used to support gearbox systems on the airframes of helicopters. When designed properly, the passive periodic strut can stop the propagation of vibration from the gearbox to the airframe within critical frequency bands, consequently minimizing the effects of transmission of undesirable vibration and sound radiation to the helicopter cabin. The theory governing the operation of this class of passive periodic struts is introduced and their filtering characteristics are demonstrated experimentally as a function of their design parameters. The presented concept of the passive periodic strut can be easily used in many applications to control the wave propagation and the force transmission in both the spectral and spatial domains in an attempt to stop/confine the propagation of undesirable disturbances.
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Chattopadhyay, A., and Y. D. Chiu. "An enhanced integrated aerodynamic load/dynamic optimization procedure for helicopter rotor blades." Structural Optimization 4, no. 2 (June 1992): 75–84. http://dx.doi.org/10.1007/bf01759920.
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Jafar, Adnan, Aamer Iqbal Bhatti, SM Ahmad, and Nisar Ahmed. "Robust gain-scheduled linear parameter-varying control algorithm for a lab helicopter: A linear matrix inequality–based approach." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 232, no. 5 (March 4, 2018): 558–71. http://dx.doi.org/10.1177/0959651818759861.
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The control performance of aerial vehicles can be easily affected by measurement error in sensor output, dynamic model error, model parameter variation, parametric uncertainty, external disturbance, and dynamic coupling. This article presents a design of robust linear parameter-varying control technique with induced L2-norm performance combined with linear matrix inequality pole region constraints for a lab-scale helicopter. A linear parameter-varying disturbance rejection observer is constructed that characterizes the L2-norm performance of the linear parameter-varying system, which enables to estimate state information not only in the presence of external disturbance but also in case of fault occurrence or unavailability of some sensor output. Therefore, the proposed robust linear parameter-varying control scheme has the tendency to provide an adaptive control solution for stability proof and robust tracking performance. The performance of the proposed technique is confirmed both in simulation and in real time. Compared to conventional output feedback H∞ control technique, the proposed control technique yields a good tracking performance in the presence of disturbance, parameter variation, and dynamic coupling.
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Ahmad, S. M., A. J. Chipperfield, and M. O. Tokhi. "Dynamic modelling and open-loop control of a twin rotor multi-input multi-output system." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 216, no. 6 (September 1, 2002): 477–96. http://dx.doi.org/10.1177/095965180221600604.
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A dynamic model for a one-degree-of-freedom (DOF) twin rotor multi-input multi-output (MIMO) system (TRMS) in hover is obtained using a black-box system identification technique. The behaviour of the TRMS in certain aspects resembles that of a helicopter; hence, it is an interesting identification and control problem. This paper investigates modelling and open-loop control of the longitudinal axis alone, while the lateral axis movement is physically constrained. It is argued that some aspects of the modelling approach presented are suitable for a class of new generation or innovative air vehicles with complex dynamics. The extracted model is employed for designing and implementing a feedforward/open-loop control. Open-loop control is often the preliminary step for development of more complex feedback control laws. Open-loop control strategies using shaped command inputs are accordingly investigated for resonance suppression in the TRMS. Digital low-pass and band-stop filter shaped inputs are used on the TRMS testbed, based on the identified vibrational modes. A comparative performance study is carried out and the corresponding results presented. The low-pass filter is shown to result in better vibration reduction.
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dos Santos, Fabio Luis Marques, Bart Peeters, Herman van der Auweraer, and Luiz Carlos Sandoval Góes. "Modal Strain Energy Based Damage Detection Applied to a Full Scale Composite Helicopter Blade." Key Engineering Materials 569-570 (July 2013): 457–64. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.457.
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The use of composites in the aircraft industry has generated a great need for structural health monitoring and damage detection systems, to allow for safer use of complex materials. Such is the case with helicopter blades - these components nowadays are mostly composed of carbon fiber or glass fiber reinforced plastics laminates, epoxy and honeycomb filled core structures. The use of composite materials on the main rotor blade also allows for more complex and efficient shapes to be designed, but at the same time, their use requires an additional effort when it comes to structural monitoring, since damage can occur and go unnoticed. This work presents experimental results for structural health monitoring method based on strain energy. The test subject is a full-scale composite helicopter main rotor blade, which is a highly flexible, slender beam that can display unusual dynamic behavior with orthotropic behavior. This damage detection method is based on the modal strain properties, and a damage detection index is used to identify and quantify damage. A test setup was built to carry out an experimental modal analysis on the main rotor blade. For that purpose, a total of 55 uniaxial accelerometers were used on the helicopter blade to measure the displacement modes of the structure. To compute the strain modes from the displacement modes, central differences approximation is used. Damage is introduced on the blade by attaching a small mass to two different locations. Experimental results show the possibility of locating damage in this case.
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Eberle, Brian F., and Jonathan D. Rogers. "Real-Time Trajectory Generation and Reachability Determination in Autorotative Flare." Journal of the American Helicopter Society 65, no. 3 (July 1, 2020): 1–17. http://dx.doi.org/10.4050/jahs.65.032008.
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Autorotation maneuvers inherently offer little margin for error in execution and induce high pilot workload, particularly as the aircraft nears the ground in an autorotative flare. Control augmentation systems may potentially reduce pilot workload while simultaneously improving the likelihood of a successful landing by offering the pilot appropriate cues. This paper presents an initial investigation of a real-time trajectory generation scheme for autorotative flare based on time-to-contact theory. The algorithm exhibits deterministic runtime performance and provides a speed trajectory that can be tracked by a pilot or inner-loop controller to bring the vehicle to a desired landing point at the time of touchdown. A low-order model of the helicopter dynamics in autorotation is used to evaluate dynamic feasibility of the generated trajectories. By generating and evaluating trajectories to an array of candidate landing points, the set of reachable landing points in front of the aircraft is determined. Simulation results are presented in which the trajectory generator is coupled with a previously derived autorotation controller. Example cases and trade studies are conducted in a six degree-of-freedom simulation environment to demonstrate overall performance as well as robustness of the algorithm to variations in target landing point, helicopter gross weight, and winds. The robustness of the reachability determination portion of the algorithm is likewise evaluated through trade studies examining off-nominal flare entry conditions and the effects of winds.