This paper proposes a neural network approximation-based nonsingular terminal sliding mode control (NN-NTSMC) approach to address the problem of trajectory tracking for robotic airships. First, ...dynamics model of an airship and control problem of trajectory tracking are formulated. Second, a nonsingular terminal sliding mode controller (NTSMC) combined with neural network (NN) approximation is designed to track the commanded trajectory. Finally, the effectiveness and robustness of the designed controller are illustrated through simulation results. Simulation results indicate that NN-NTSMC reduces chattering effectively and ensures faster convergence and better tacking precision against linear hyperplane-based sliding mode control (LSMC).
In this work, fiber-reinforced laminates for the envelope (hull) of high-altitude airships were developed using a novel design concept utilizing ethylene vinyl alcohol (EVOH) as the adhesive ...component layer with high gas barrier properties. The other component layers of the laminates included poly(p-phenylene benzobisoxazole) (Zylon®) fabric, metalized Mylar® (polyester) and metallized Kapton® (polyimide). The envelope materials were developed in two different strength categories. In the first category, three laminate designs were developed with strength ranging from 945-970 N/cm. The second group had one laminate design with a strength of 702 N/cm. These laminates with basis weights ranging from 103-113 g/m
2
, are the lightest envelope materials developed to date. As a function of their high strength and low basis weights, the new envelope materials have significantly higher specific strength (ranging from 911-925 kN.m/kg) compared to other envelope constructions published in the open literature. Other outstanding properties of the laminates include low helium permeability ranging from 0.4-8.0 cc/m
2
.24 hr.1 atm, high tear strength, UV and visible light (UV-Vis) resistance, and high creep resistance.
According to the requirements of a foreign high-altitude airship project, the Single-Rotation-Propeller (SRP) was designed under the maximum endurance factor criterion. The spacing influence on the ...Contra-Rotation-Propeller (CRP) was studied by numerical simulation analysis, the performance of front and rear propeller was compared with SRP. The result indicated that CRP was more efficient than SPR, the CRP has enormous potential in enhancing the aerodynamic performance.
Cryogenic technology has been developed cooperatively with infrared detection technology, which is of great significance for the development of space science and technology. To illustrate this ...coordinated development, the relationships between the infrared wavelength and the dark current in detectors with cryogenic temperature are analyzed, which shows the importance of cryogenic technology for infrared detection. Based on an analysis of infrared detection characteristics and cryogenic temperature requirements in different temperature zones, the development direction of cryogenic technology for infrared detection in space is analyzed and combined with the application of cryogenic technology in several key infrared space missions.
•A new method is proposed to solve the problem of height fluctuations.•A multi-node thermodynamic model of the airship is established.•The venting and inflation are considerably affected by the ...season and latitude.•Mesh refinement could have a slightly effect on the temperatures of the airbags.
A new fixed-point adjustment method for an airship is proposed to solve the problem of height instability due to dramatic daily-temperature swings. The airship membrane was discretized into a triangular element in this paper to enhance the computing accuracy of the method, and the multi-node thermodynamic model of the airship is established. The thermal performance of the airship is obtained using the Runge–Kutta method. The influences of season and latitude on the membrane, helium temperature and exhaust/inflation performance were investigated. The effect of the film elements on thermal performance is also discussed in detail. These results are helpful for the optimal design and operation of stratospheric airships.
The indoor unmanned airship is a lighter-than-air aircraft that can hover in the air for a long time without consuming energy. Indoor unmanned airships are widely used in indoor inspections, special ...operations, commercial advertising, education and scientific research. In this paper, an indoor unmanned airship propelled by ionic wind is designed. The airship can complete motions such as forward and yaw, and almost no noise and vibration are generated during the working process.
This article investigates the distributed fault-tolerant time-varying formation control problem for multiple unmanned airships (UAs) against limited communication ranges and input saturation to ...achieve the safe observation of a smart city. To address the strongly nonlinear functions caused by the time-varying formation flight with limited communication ranges and bias faults, intelligent adaptive learning mechanisms are proposed by incorporating fuzzy neural networks. Moreover, Nussbaum functions are introduced to handle the input saturation and loss-of-effectiveness faults. The distinct features of the proposed control scheme are that time-varying formation flight, actuator faults including bias and loss-of-effectiveness faults, limited communication ranges, and input saturation are simultaneously considered. It is proven by Lyapunov stability analysis that all UAs can achieve a safe formation flight for the smart city observation even in the presence of actuator faults. Hardware-in-the-loop experiments with open-source Pixhawk autopilots are conducted to show the effectiveness of the proposed control scheme.
Abstract
Engineered products have economic, environmental, and social impacts, which comprise the major dimensions of sustainability. This paper seeks to determine the interaction between design ...parameters when the social impacts are incorporated into the design process. Social impact evaluation is increasing in importance similar to what has happened with environmental impact consideration in recent years in the design of engineered products. Concurrently, research into new airship design has increased, however airships have yet to be reintroduced at a large scale and for a range of applications in society. Although airships have the potential for positive environmental and economic impacts, the social impacts are still rarely considered. This paper presents a case study of the hypothetical introduction of airships in the Amazon to help local farmers transport their produce to market. It explores the design space in terms of the airship's social impacts connected to the design parameters. The social impacts are found to be dependent not only on the social factors and airship design parameters, but also on the farmer-airship system, suggesting that socio-technical systems design will benefit from integrated social impact metric analysis.
Aiming at flight property of airship, a trajectory tracking controller of airship horizontal model is designed based on active disturbance rejection control (ADRC). The six Degree of Freedom (DOF) ...dynamic model of airship is simplified at a horizontal plane. ADRC is used to realize the decoupling control for the multivariable system. The uncertain items of the model and external disturbances are estimated by the extended state observer (ESO) and dynamic feedback compensation is carried on at real time. The disturbance of wind is added to the simulation environment. The simulation results show that the designed tracking controller can overcome the influences of uncertain items of the model and external disturbances, and track the desired trajectory rapidly and steadily, and possess good robustness and control performances.
The interest in stratospheric airships has increased and great progress has been achieved since the late 1990s due to the advancement of modern techniques and the wide range of application demands in ...military, commercial, and scientific fields. Thermal issues are challenging for stratospheric airships, while there is no systematic review on this aspect found yet. This paper presents a comprehensive literature review on thermal issues of stratospheric airships. The main challenges of thermal issues on stratospheric airships are analyzed. The research activities and results on the main thermal issues are surveyed, including solar radiation models, environmental longwave radiation models, external convective heat transfer, and internal convective heat transfer. Based on the systematic review, guides for thermal model selections are provided, and topics worthy of attention for future research are suggested.
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