Showing papers on "Landing gear published in 2020"

Robust Adaptive Control for an Aircraft Landing Gear Equipped with a Magnetorheological Damper

Abstract: A landing gear of an aircraft is required to function at touchdown in different landing scenarios with parametric uncertainties. A typical passive damper in a landing gear has limited performance in differing landing scenarios, which can be overcome with magnetorheological (MR) dampers. An MR damper is a semi-active system that can adjust damping force by changing the amount of electric current applied to it. This paper proposes a new robust controller based on model reference sliding mode control and adaptive hybrid control to improve the efficiency of absorbing landing impact energy, not only considering the variables of aircraft weight and sink speed but also managing uncertainties, such as ambient temperature and passive damping coefficient. To verify the effectiveness of the proposed controller, comparative numerical simulations were performed with a passive damper, a skyhook controller, and the proposed controller under various landing scenarios. The simulation results show that the proposed controller improves the total energy absorber efficiency by up to 10% higher than that of the skyhook controller. In addition, the proposed controller is demonstrated to have better adaptability and robustness than the other control algorithms in the differing landing scenarios and parametric uncertainties.

Improving Multirotor Landing Performance on Inclined Surfaces Using Reverse Thrust

Abstract: Conventional multirotors are unable to land on inclined surfaces without specialized suspensions and adhesion devices. With the development of a bidirectional rotor, landing maneuvers could benefit from rapid thrust reversal, which would increase the landing envelope without involving the addition of heavy and complex landing gears or reduction of payload capacity. This letter presents a model designed to accurately simulate quadrotor landings, the behavior of their stiff landing gear, and the limitations of bidirectional rotors. The model was validated using experimental results on both low-friction and high-friction surfaces, and was then used to test multiple landing algorithms over a wide range of touchdown velocities and slope inclinations to explore the benefits of reverse thrust. It is shown that thrust reversal can nearly double the maximum inclination on which a quadrotor can land and can also allow high vertical velocity landings.

Effects of magnetic core parameters on landing stability and efficiency of magnetorheological damper-based landing gear system:

Abstract: In this research, a new type of magnetorheological damper for a small-sized aircraft landing gear system is proposed and its performance is evaluated with respect to design parameters of the magnet...

Control System for Vertical Take-Off and Landing Vehicle's Adaptive Landing Based on Multi-Sensor Data Fusion.

Abstract: Vertical take-off and landing unmanned aerial vehicles (VTOL UAV) are widely used in various fields because of their stable flight, easy operation, and low requirements for take-off and landing environments. To further expand the UAV’s take-off and landing environment to include a non-structural complex environment, this study developed a landing gear robot for VTOL vehicles. This article mainly introduces the adaptive landing control of the landing gear robot in an unstructured environment. Based on the depth camera (TOF camera), IMU, and optical flow sensor, the control system achieves multi-sensor data fusion and uses a robotic kinematical model to achieve adaptive landing. Finally, this study verifies the feasibility and effectiveness of adaptive landing through experiments.

British Airways is Ordering up to 42 Boeing 777-9s Aeronaves to Modernize the UK Flag Carriers Long-Haul Fleet

Abstract: The Boeing 777 (sometimes referred to as Triple 7) is a large-capacity subsonic long-haul bomber aircraft built by the American company Boeing. This type of aircraft holds the current record of autonomy for commercial jets (17,450 km without food). Other special features of the aircraft include the perfect circular fuselage, a set of six wheels on each axle of the landing gear and the ability to be equipped with the high-performance General Electric GE90 engine. The 777 has been exclusively designed using CAD technology (with CATIA version 3), being the first airplane designed without building test structures before. Verification of joints and construction techniques has also been done digitally, with all the structures built up being included in the actual aircraft. The aircraft was designed to serve as an immediately superior Boeing 767 model and was built in airline consultancy (United Airlines, American Airlines, Delta Air Lines, ANA, British Airways, JAL, Qantas and Cathay Pacific) came from United Airlines in 1990 and the first flight took place on June 14, 1994, at the Boeing factory in Everett, near Seattle. It was the first ETOPS 180 bimonthly aircraft (it can fly up to 180 min from any airport able to take it). It is one of the best-selling (two-color) passenger airplanes in history, of which 988 were ordered, of which 635 were already delivered to the airlines. Its main competitors are Airbus A330 (for medium distance routes), Airbus A340 (for long-distance routes, with the claim that this model has the disadvantage of having four engines) and the future of the Airbus A350XWB-1000. Boeing plans to replace the model with the Yellowstone 3 code model in 2012-2015. The aircraft is equipped with modern technologies: Digital flight instruments offered by Honeywell LCD panels, fly-by-wire control, manual back-up systems, fully controllable avionics from software, use of composite materials on a larger surface (9% by mass), optical fiber as the primary transmission and control system for avionics, the largest and most powerful engine ever installed in a commercial aircraft (GE90-115B1) and the largest landing gear plus, the landing train allows the highest maximum weight on a wheel of all commercial jets - 23.73 t). The aircraft also uses classic technologies - such as the classic jump, unlike the Airbus models that have switched to joysticks. Similarly, the front section (section 41) is identical to that of the Boeing 767. For the comfort of pilots and crew members over long distances, there is a special resting space above the passenger cabin, complete with beds. In fact, the entire interior of the plane was new and then used in other models.

LocoGear: Locomotion Analysis of Robotic Landing Gear for Multicopters

Abstract: Nowadays, there are few unmanned aerial vehicles (UAVs) that are capable of landing on uneven surfaces or moving on the complex ground. A drone having both of these functionalities can significantly improve its performance in accomplishing difficult tasks, such as monitoring and exploring various types of terrain, searching for survivors, and delivering medical aid or repair kits in an unstructured dynamic environment, e.g., rescue operation following an earthquake. This article presents a motion analysis of the gait of an adaptive landing platform for multicopters. This landing gear has four robotic legs facilitated with torque sensors in the knee joints. Though it had been developed to provide adaptive landing on uneven surfaces, we decided to exploit the system for terrain locomotion purposes. For this purpose, we have analyzed the center of mass trajectory to evaluate the possible trajectory of the robot. Based on the result of this experimental analysis, we propose a LocoGear, a novel algorithm for locomotion of UAV equipped with the robotic landing gear. The servomotor torques were estimated using Lagrangian dynamic formulation and kinetostatic methods. We conducted experiments to verify the LocoGear approach based on feedforward control that proves the capability of landing gear to move along the desired trajectory. We achieved the robot motion along the straight line with the standard deviation of length in each step of 9.8 mm and standard deviation in yaw of 9°.

Intelligent Control Based on a Neural Network for Aircraft Landing Gear with a Magnetorheological Damper in Different Landing Scenarios

Abstract: A typical oleo-pneumatic shock-absorbing strut (classic traditional passive damper) in aircraft landing gear has a metering pin extending through the orifice, which can vary the orifice area with the compression and extension of the damper strut. Because the metering pin is designed in a single landing condition, the traditional passive damper cannot adjust its damping force in multiple landing conditions. Magnetorheological (MR) dampers have been receiving significant attention as an alternative to traditional passive dampers. An MR damper, which is a typical semi-active suspension system, can control the damping force created by MR fluid under the magnetic field. Thus, it can be controlled by electric current. This paper adopts a neural network controller trained by two different methods, which are genetic algorithm and policy gradient estimation, for aircraft landing gear with an MR damper that considers different landing scenarios. The controller learns from a large number of trials, and accordingly, the main advantage is that it runs autonomously without requiring system knowledge. Moreover, comparative numerical simulations are executed with a passive damper and adaptive hybrid controller under various aircraft masses and sink speeds for verifying the effectiveness of the proposed controller. The main simulation results show that the proposed controller exhibits comparable performance to the adaptive hybrid controller without any needs for the online estimation of landing conditions.

Implementation of tonal cavity noise estimations in landing gear noise prediction models

Abstract: Landing gear noise is considered the dominant airframe noise source on aircraft during approach. Previous studies indicated the presence of a strong tonal sound on flyovers of several commercial aircraft types, and suggested that it was caused by the interaction of open cavities in the nose landing gear (NLG) system with the flow. Airframe noise prediction models, however, do not account for parasitic noise sources, such as cavities, which can lead to severe underpredictions of the noise levels generated by NLG systems. In this paper, a method to improve the well–known landing gear noise prediction methods of Fink and Guo is suggested. The study is based on aircraft flyover measurements performed with a microphone array which, together with acoustic imaging techniques, allows for the separation of the noise emissions coming from the NLG. Flyover recordings from several Airbus A320 aircraft under operational conditions are analyzed and, based on the tonal frequency observed, potential cavity dimensions are suggested. The sound pressure levels of the narrowband tones were found to scale with approximately the 9th power of the airspeed. A simple correction formula for accounting for this type of cavity noise in the prediction models, depending on the aircraft velocity, is proposed. By applying this correction, the overall noise level predictions of the updated noise models become more accurate, reducing their average difference with the experimental data from 5 dB to just 1 dB.

Nose Landing Gear Simple Adaptive Shimmy Suppression System

Abstract: The occurrence of shimmy vibration in aircraft nose landing gear can cause an increase of fatigue stress on the nose landing gear mechanical elements that can eventually lead to high wearing of com...

Real-time Landing Gear Control System Based on Adaptive 3D Sensing for Safe Landing of UAV

Abstract: Unmanned aerial vehicles (UAVs) have been utilized in many applications, such as transportation, land surveying, and exploration. To expand the safe flying area for UAVs, a technology for safe landing on ground with unknown shapes is important. Here, we propose a real-time landing gear control system with adaptive 3D sensing for safe landing on an unknown ground. This system performs adaptive 3D sensing in which the sensing area is changed according to the position and attitude of the UAV to always measure the area of contact between the landing gears and ground when landing. Furthermore, according to the measured ground shape, the proposed system controls the lengths of landing gears in real time to realize safe landing where all the landing gears contact the ground simultaneously. We simulated landing on an unknown ground and evaluated the contact timings of landing gears. The proposed system could update the heights of contact points of two landing gears at a rate of 100 Hz. Moreover, the contact time lags of the landing gears were improved. Subsequently, the landing gears contacted the ground almost simultaneously when the lengths of landing gears were controlled using adaptive 3D sensing. The proposed system offers high potential and room for further improvement on safe landing of UAVs.

Health Monitoring of Landing Gear Retraction/Extension System Based on Optimized Fuzzy C-Means Algorithm

Abstract: The landing gear retraction/extension(R/E) system has a critical impact on the safety of aircraft’s take-off and landing, and its health status is important to decision-making of the system’s prognostics and health management (PHM). With flight parameter data, a method to monitor the health of aircraft landing gear R/E system is proposed based on the improved fuzzy c-means algorithm (FCM). The landing gear health status are classified by the FCM cluster, and the granularity principle and density function are utilized to optimize the number of FCM algorithm clusters and the initial clustering center to better classification. At the same time, an optimized multi-dimensional scaling algorithm (MDS) is used to obtain low-dimensional features which facilitate cluster analysis. And the algorithm comparison and case analysis results show that the proposed method has a great health monitoring effect.

Numerical simulation of aeroacoustic noise from landing gear and rectangular cavity

Abstract: This paper is aimed at researching the interaction between aeroacoustic noise radiated from a rectangular cavity (gear bay) and from landing gear. It is a complicated flow-induced noise problem, in...

Simulasi umur fatik rangka main landing gear menggunakan metode elemen hingga

Abstract: The landing gear is one crucial component in an Unmanned Aerial Vehicle (UAV) aircraft construction. Landing gear serves as the main supporting component of aircraft load when landing and take off. This research aims to investigate the fatigue design life of the main landing gear on the UAV aircraft. The main landing gear frame design used Autodesk Inventor Professional 2017, while finite element analysis used Ansys Workbench software. It is subjected to a load of 1500 N with a loading fully-reserved. The prediction for fatigue life using Gerber mean stress theory. The material of the main landing gear frame is Aluminum alloy 6061. The simulation results show that the main landing gear frame has a minimum fatigue life of up to 3.5 x 10 7 cycles with a minimum safety factor of 1.43.

Approach and Landing Aircraft On-Board Parameters Estimation with LSTM Networks

Abstract: This paper addresses the problem of estimating aircraft on-board parameters using ground surveillance available parameters. The proposed methodology consists in training supervised Neural Networks with Flight Data Records to estimate target parameters. This paper investigates the learning process upon three case study parameters: The fuel flow rate, the flap configuration, and the landing gear position. Particular attention is directed to the generalization to different aircraft types and airport approaches. From the Air Traffic Management point of view, these additional parameters enable a better understanding and awareness of aircraft behaviors. These estimations can be used to evaluate and enhance the air traffic management system performance in terms of safety and efficiency.

Structural design and optimization of a novel shimmy damper for nose landing gears

Abstract: Passive vibration suppression devices known as shimmy dampers are vital in maintaining stability and safety of certain landing gears. Yet, systematic design, performance analysis, and optimization of such devices are rarely discussed in the literature. This paper presents structural design optimization of a novel shimmy damper for nose landing gears. This new design is a multifunctional mechanism integrating the shimmy damper into the torque link system of the nose landing gear. It features symmetric load distribution, and it can be tailored to existing nose landing gears. Here, the damper design concept is developed in the structural sense and optimized for the nose landing gear of a Piper Cheyenne aircraft. Dynamic loads from a representative shimmy scenario are employed in the analysis and design procedures. Utilizing equivalent static load method, topology optimization with transient loads is performed to obtain optimal material distribution satisfying the objective function and constraints. Flexible multibody dynamics analysis based on a high-fidelity finite element model is utilized in the analysis of design candidates and for validating the final design. To ensure adequate strength under the dynamic torque loads and to offer sufficient damping needed for stabilizing the nose landing gear, a three-piece torque link mechanism emerged through multiple design iterations guided by the topology optimization. Using numerical simulations, the final design is shown to satisfy the strength requirement while providing sufficient damper stroke. The results from the present study signal a vast potential in improving shimmy mitigation strategies by eliminating the need for costly redesigns of landing gears susceptible to shimmy.

Detection of Aircraft Touchdown Using Longitudinal Acceleration and Continuous Wavelet Transformation

Abstract: The paper presents a methodology enabling the detection of aircraft touchdowns based on data obtained from accelerometers attached to the structural parts of the airframe in the cockpit or passenger compartment. Precise determination of the moment and place of touchdown of the main landing gear is challenging when analysing parameters such as height, flight speed and rate of descent. During the tests of the I-31T aircraft, it turned out that vibrations of the aircraft structure caused by the contact of the front and main landing gear with the ground have a repetitive character. In particular, this applies to longitudinal acceleration. The use of continuous wavelet analysis (CWT) allowed finding unique periodic features of the landing phenomenon that distinguish it from other forms of vibration occurring in individual flight phases. Ground and flight observations of experimental aeroplane MP-02 Czajka verified the proposed method of virtual touchdown detection. The results presented in this paper justify that this method may find broader application, especially for the light aircraft class.

Bio-inspired Inverted Landing Strategy in a Small Aerial Robot Using Policy Gradient

Abstract: Landing upside down on a ceiling is challenging as it requires a flier to invert its body and land against the gravity, a process that demands a stringent spatiotemporal coordination of body translational and rotational motion. Although such an aerobatic feat is routinely performed by biological fliers such as flies, it is not yet achieved in aerial robots using onboard sensors. This work describes the development of a bio-inspired inverted landing strategy using computationally efficient Relative Retinal Expansion Velocity (RREV) as a visual cue. This landing strategy consists of a sequence of two motions, i.e. an upward acceleration and a rapid angular maneuver. A policy search algorithm is applied to optimize the landing strategy and improve its robustness by learning the transition timing between the two motions and the magnitude of the target body angular velocity. Simulation results show that the aerial robot is able to achieve robust inverted landing, and it tends to exploit its maximal maneuverability. In addition to the computational aspects of the landing strategy, the robustness of landing is also significantly dependent on the mechanical design of the landing gear, the upward velocity at the start of body rotation, and timing of rotor shutdown.

Stress analysis of Landing gear of light Unmanned Aerial Vehicle

Abstract: The landing gear system of an aircraft absorbs energy from the impact of landing. Numerical simulation has become great tool for the assessment of the landing gear dynamics as well as for aircraft structure and landing gear interaction. This paper basically describes the normal structural behavior of a simple landing gear structure model system and accurately simulates the energy absorbed by the gear system without adding substantial complexity with the model. It carries the structure aircraft weight at all required ground operations including landing, take off, taxiing and towing. The stress results obtained from the finite element analysis is used to calculate the factor of safety. This work also focuses on landing gear of small unmanned aerial vehicles, where the landing gears used are of leaf spring type. It has been seen that the stresses are very high during greater impact speeds, which resulted in less factor of safety.

Comprehensive analysis on mechanical behavior of airworthy raw materials for aircraft landing gear system

Abstract: The development of new materials for the airplane and aviation is moving at a quick pace. The new materials must achieve robustness, strength, weight decrease, cost financial aspects, materials test data, and environmental- friendly. The materials test information is being utilized for the design of landing gear and other structural components for aircrafts. The landing gear comprises of shock strut, pin, bush, torsional link, wheel, tire, axle, up lock, trailing arm and retraction component. In this paper, yield and ultimate strength, percentage elongation, percentage area of reduction and young’s modulus are find out by conducting tensile test on the raw materials such as aluminium alloy, alloy steel and titanium alloy used in the landing gear system and to conduct structural analysis test on landing gear components such as pin, bush and torsional link. These significant parameters obtained from the tensile testing and structural analysis are valuable for the choice of raw materials for the structure of airplane segments. Thus, the mechanical tested data for different raw materials have corresponded with the authentication of affirmation given by the producer and in this way, this investigation will be especially helpful for assembling the landing gear segments by our Indian defense sector.

A New Magnetorheological Fluids Damper for Unmanned Aerial Vehicles

Abstract: This case study proposes the development of damping technology using intelligent materials as working fluids for the landing gear of Unmanned Aerial Vehicles (UAV) during the landing process. The intelligent materials to be used are magnetorheological fluids (MRF), a liquid that has variable viscosity to magnetic fields. This intelligent material can improve the performance of the damping device by allowing it to have variable damping features through viscosity changing. The proposed UAV magnetorheological (MR) dampers design utilizes a magnetic valve that has an annular flow channel configuration with a 0.5 mm gap size equipped with an electromagnetic coil with adjustable current input. Both gap size and the current input selection affect the performance of the damping device. This study discusses the performance to reduce shock during the landing process. The performance is evaluated by analyzing the pressure drop and damping force produced by the device with changes in the current input variation. The numerical and simulation results show that the damping characteristics of the device could be adjusted by changing the current input to the electromagnet. The obtained results are then adjusted based on the needs of the UAV in landing purposes. The study proved that the device performance is suitable to absorb shock during the landing process of the UAV.

On the Issue of Increasing the Stability and Controllability of Aircraft of Non-Traditional Schemes When Moving on the Ground

Abstract: The research proposes an approach to solving the problems of stability and controllability of aircraft of the aerodynamic scheme "flying wing" in terms of movement on the ground, which consists in combining landing gear systems into an automatic integrated control contour. The analysis of peculiarities of movement on the ground is carried out, disadvantages and limits of application of available control methods are specified. Development of a dynamic aircraft model for virtual testing of control algorithms is described. The conclusion is made about practical advantages that are expected to be obtained because of the introduction of the integrated control contour of landing gear systems. Are additional possibilities of the proposed approach: in addition to using on unmanned aerial vehicles to operate in automatic control mode, the development can be used on manned and remotely piloted aircraft as an auxiliary system that helps the pilot to withstand the take-off and run direction under random energetic disturbing influences, similar to that used on modern cars of assisting systems such as ESP (Electronic Stability Program) -electronic dynamic stabilization system.

How future aircraft can benefit from a steerable main landing gear for crosswind operations

Abstract: Many unconventional configurations for future aircraft, such as aircraft with very high aspect ratio wings or blended wing bodies, suffer from adverse flying characteristics for crosswind operations. Although the reasons for such undesirable behavior are different, coming from either tight geometric limitations, such as small bank angle allowances close to ground, or unfavorable flying qualities in the lateral motion, the consequences are challenging characteristics for take-off or landing under crosswind. In the presented study, a crosswind landing assistance system that makes use of a steerable main landing gear was designed and demonstrated in simulator trials. With such a system, the so-called de-crab maneuver is obsolete and the aircraft can touch down in crabbed motion. During roll-out on ground, the de-crab is performed automatically and the aircraft is kept on the runway centerline. A special concept for manual steering during this automatic de-crab on ground is introduced in the paper. The system is demonstrated in an A320 full-flight simulator with airline pilots, showing a good performance of the system and satisfactory pilot acceptance. The simulation results also show that the side forces acting on the landing gears could be reduced significantly with steerable main landing gears. This raises the hope that with such a system, the landing gear could possibly be designed lighter, saving at least some of the additional weight and cost for the necessary steering actuators of the main landing gear.