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1 – 10 of 130Yawei Wang, Weihu Zhou, Xiaoquan Han, Zhongyu Wang and Jinbin Ding
The purpose of this paper is to describe a strap‐down image stable strategy for multi‐load optoelectronic imaging platform hung below a tethered aerostat.
Abstract
Purpose
The purpose of this paper is to describe a strap‐down image stable strategy for multi‐load optoelectronic imaging platform hung below a tethered aerostat.
Design/methodology/approach
Four two dimension pods, each with a visible light camera, are fixed on the optoelectronic platform. A POS (Position and Orientation System) is used to acquire the attitude rate data of optoelectronic platform, while the data can be coupled to the pods' servo systems through corresponding coordinate rotation, then the motors of pods will adjust the line of sight to the opposite way to keep the stabilization of image exported by visible light camcorders. Simultaneously, two rate gyros are installed at the inner frame of each pod, which are used as a backup to avoid the failure of POS.
Findings
Using one attitude and position measurement system can realize the stabilization of multi optoelectronic pods, which is same as or even better than the ratio gyro stabilization.
Research limitations/implications
As the tethered aerostat is a flexible body, it is affected a lot by the wind speed and wind direction at the low height (<1,000 m), which leads to the motors of pods always adjust the line of sight to the mechanical limiting of pods.
Practical implications
Strap‐down stabilization technology has been successfully used in the tethered aerostat monitoring platform to surveillance Shanghai World EXPO site. Long time experiments verify the feasible and effective of the multi‐load stabilization technology. The impact on the image by the adjustment of servos is less than 10 percent of the whole view of sight.
Originality/value
The paper introduces a strap‐down stabilization technology for multi‐load tethered aerostat platform, which is more suitable to be applied in the platform of relatively minor attitude change, like the airborne multi‐load platform and multi‐load UAV (unmanned aerial vehicle) platform.
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Hongyan Zhu, Pengzhen Lv, Xiaochong Wu, Yuansheng Wang, Wei Liu, Huagang Lin and Zhufeng Yue
This paper aims to propose a two-stage vibration isolation system for large airborne equipment to isolate aircraft vibration load.
Abstract
Purpose
This paper aims to propose a two-stage vibration isolation system for large airborne equipment to isolate aircraft vibration load.
Design/methodology/approach
First, the vibration isolation law of the discrete model of large airborne equipment under different damping ratios, stiffness ratios and mass ratios is analyzed, which guides the establishment of a three-dimensional solid model of large airborne equipment. Subsequently, the vibration isolation transfer efficiency is analyzed based on the three-dimensional model of the airborne equipment, and the angular and linear vibration responses of the two-stage vibration isolation system under different frequencies are studied.
Findings
Finally, studies have shown that the steady-state angular vibration at the non-resonant frequency changes little. In contrast, the maximum angular vibration at the resonance peak reaches 0.0033 rad, at least 20 times the response at the non-resonant frequency. The linear vibration at the resonant frequency is at least 2.14 times the response at the non-resonant frequency. Obviously, the amplification factor of linear vibration is less than that of angular vibration, and angular vibration has the most significant effect on the internal vibration of airborne equipment.
Originality/value
The two-stage vibration isolation equipment designed in this paper has a positive guiding significance for the vibration isolation design of large airborne equipment.
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Peng Gao, Xiuqin Su and Wenbo Zhang
This study aims to promote the anti-disturbance and tracking accuracy of optoelectronic stabilized platforms, which ensure that optical detectors accurately track targets and…
Abstract
Purpose
This study aims to promote the anti-disturbance and tracking accuracy of optoelectronic stabilized platforms, which ensure that optical detectors accurately track targets and acquire high-quality images.
Design/methodology/approach
An improved active disturbance rejection control (ADRC) strategy based on model-assisted double extended state observers (MDESOs) is proposed in this paper. First, by establishing an auxiliary model, the total disturbances are separated into two parts: inner and external disturbances. Then, MDESOs are designed to estimate the two parts by separately using two parallel ESOs, by which the controlled plant is adjusted to the ideal pure integral series. Simultaneously, combined with the nonlinear state error feedback, an overall control strategy is established.
Findings
Compared with the conventional ADRC and proportional derivative, the improved ADRC (IADRC) has stronger robustness and adaptability and effectively reduces the requirements for model accuracy and the gain of the ESO. The error of the auxiliary model is tolerated to exceed 50%, and the parameter values of the MDESOs are reduced by 90%.
Originality/value
The total disturbance rejection rate of the proposed strategy is only 3.11% under multiple disturbances, which indicates that the IADRC strategy significantly promotes anti-disturbance performance.
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Paweł Rzucidło, Tomasz Rogalski, Grzegorz Jaromi, Damian Kordos, Piotr Szczerba and Andrzej Paw
The purpose of this paper is to describe simulation research carried out for the needs of multi-sensor anti-collision system for light aircraft and unmanned aerial vehicles.
Abstract
Purpose
The purpose of this paper is to describe simulation research carried out for the needs of multi-sensor anti-collision system for light aircraft and unmanned aerial vehicles.
Design/methodology/approach
This paper presents an analysis related to the practical possibilities of detecting intruders in the air space with the use of optoelectronic sensors. The theoretical part determines the influence of the angle of view, distance from the intruder and the resolution of the camera on the ability to detect objects with different linear dimensions. It has been assumed that the detection will be effective for objects represented by at least four pixels (arranged in a line) on the sensor matrix. In the main part devoted to simulation studies, the theoretical data was compared to the obtained intruders’ images. The verified simulation environment was then applied to the image processing algorithms developed for the anti-collision system.
Findings
A simulation environment was obtained enabling reliable tests of the anti-collision system using optoelectronic sensors.
Practical implications
The integration of unmanned aircraft operations in civil airspace is a serious problem on a global scale. Equipping aircraft with autonomous anti-collision systems can help solve key problems. The use of simulation techniques in the process of testing anti-collision systems allows the implementation of test scenarios that may be burdened with too much risk in real flights.
Social implications
This paper aims for possible improvement of safety in light-sport aviation.
Originality/value
This paper conducts verification of classic flight simulator software suitability for carrying out anti-collision systems tests and development of a flight simulator platform dedicated to such tests.
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Keywords
Dong Mei and Zhu-Qing Yu
This paper aims to improve the anti-interference ability of the airborne radar stabilization platform, especially the ability to suppress continuous disturbance under complex air…
Abstract
Purpose
This paper aims to improve the anti-interference ability of the airborne radar stabilization platform, especially the ability to suppress continuous disturbance under complex air conditions to ensure the clarity and stability of airborne radar imaging.
Design/methodology/approach
This paper proposes a new active disturbance rejection control (ADRC) strategy based on the cascade extended state observer (ESO) for airborne radar stabilization platform, which adopts two first-order ESOs to estimate the angular velocity value and the angular position value of the stabilized platform. Then makes the error signal which subtracts the estimated value of ESO from the output signal of the tracking-differentiator as the input signal of the nonlinear state error feedback (NLSEF), and according to the output signal of the NLSEF and the value which dynamically compensated the total disturbances estimated by the two ESO to produce the final control signal.
Findings
The simulation results show that, compared with the classical ADRC, the ADRC based on the cascade ESO not only estimates the unknown disturbance more accurately but also improves the delay of disturbance observation effectively due to the increase of the order of the observer. In addition, compared with the classical PID control and the classical ADRC, it has made great progress in response performance and anti-interference ability, especially in the complex air conditions.
Originality/value
The originality of the paper is the adoption of a new ADRC control strategy based on the cascade ESO to ameliorate the anti-interference ability of the airborne radar stabilization platform, especially the ability to suppress continuous interference under complex air conditions.
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Erika Anneli Pärn and David Edwards
The purpose of this paper is to present a literature review of laser scanning and 3D modelling devices, modes of delivery and applications within the architecture, engineering…
Abstract
Purpose
The purpose of this paper is to present a literature review of laser scanning and 3D modelling devices, modes of delivery and applications within the architecture, engineering, construction and owner-operated sector. Such devices are inextricably linked to modern digital built environment practices, particularly when used in conjunction with as-built building information modelling (BIM) development. The research also reports upon innovative technological advancements (such as machine vision) that coalesce with 3D scanning solutions.
Design/methodology/approach
A synthesis of literature is used to develop: a hierarchy of the modes of delivery for laser scan devices; a thematic analysis of 3D terrestrial laser scan technology applications; and a componential cross-comparative tabulation of laser scan technology and specifications.
Findings
Findings reveal that the costly and labour intensive attributes of laser scanning devices have stimulated the development of hybrid automated and intelligent technologies to improve performance. Such developments are set to satisfy the increasing demand for digitisation of both existing and new buildings into BIM. Future work proposed will seek to: review what coalescence of digital technologies will provide an optimal and cost-effective solution to accurately re-constructing the digital built environment; conduct case studies that implement hybrid digital solutions in pragmatic facilities management scenarios to measure their performance and user satisfaction; and eliminate manual remodelling tasks (such as point cloud reconstruction) via the use of computational intelligence algorithms integral within cloud-based BIM platforms.
Originality/value
Although laser scanning and 3D modelling have been widely covered en passant within the literature, scant research has conducted a holistic review of the technology, its applications and future developments. This review presents concise and lucid reference guidance that will intellectually challenge, and better inform, both practitioners and researchers.
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Hongyan Zhu, Xiaochong Wu, Pengzhen Lv, Yuansheng Wang, Huagang Lin, Wei Liu and Zhufeng Yue
Improvement and optimization design of a two-stage vibration isolation system proposed in this paper are conducted to ensure the device of electronic work effective.
Abstract
Purpose
Improvement and optimization design of a two-stage vibration isolation system proposed in this paper are conducted to ensure the device of electronic work effective.
Design/methodology/approach
The proposed two-stage vibration isolation system of airborne equipment is optimized and parameterized based on multi-objective genetic algorithm.
Findings
The results show that compared with initial two-stage vibration isolation system, the angular vibration of the two-stage vibration isolation system becomes 3.55 × 10-4 rad, which decreases by 89%. The linear isolation effect is improved by at least 67.7%.
Originality/value
The optimized two-stage vibration isolation system effectively improves the vibration reduction effect, the resonance peak is obviously improved and the reliability of the mounting bracket and the shock absorber is highly improved, which provides an analysis method for two-stage airborne equipment isolation design under complex dynamic environment.
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Keywords
The purpose of this paper is to evaluate the detection performance of infrared photoelectric detection system and establish stable tracking platform.
Abstract
Purpose
The purpose of this paper is to evaluate the detection performance of infrared photoelectric detection system and establish stable tracking platform.
Design/methodology/approach
This paper puts forward making use of the finite element analysis method to set up the infrared radiation characteristics calculation model of flying target in infrared photoelectric detection system; researches the target optical characteristics based on the target imaging detection theory; sets up the heat balance equation of target’s surface node and gives the calculation method of total radiation intensity of flying target; and deduces the target detection distance calculation function; studies the changed regulation of radiation energy that charge coupled device (CCD) gain comes from target surface infrared heat radiations under different sky background luminance and different target flight attitude.
Findings
Through calculation and experiment analysis, the results show that when the target’s surface area increases or the target flight velocity is higher, the radiation energy that CCD obtained is higher, which is advantageous to the target stable detection in infrared photoelectric detection system.
Originality/value
This paper uses the finite element analysis method to set up the infrared radiation characteristics calculation model of flying target and give the calculation and experiment results; those results can provide some data and improve the design method of infrared photoelectric detection system, and it is of value.
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Keywords
Jiaqi Jia and Haibin Duan
The purpose of this paper is to propose a novel target automatic recognition method for unmanned aerial vehicle (UAV), which is based on backpropagation – artificial neural…
Abstract
Purpose
The purpose of this paper is to propose a novel target automatic recognition method for unmanned aerial vehicle (UAV), which is based on backpropagation – artificial neural network (BP-ANN) algorithm, with the objective of optimizing the structure of backpropagation network, to increase the efficiency and decrease the recognition time. A hardware-in-the-loop system for UAV target automatic recognition is also developed.
Design/methodology/approach
The hybrid model of BP-ANN structure is established for aircraft automatic target recognition. This proposed method identifies controller parameters and reduces the computational complexity. Approaching speed of the network is faster and recognition accuracy is higher. This kind of network combines or better fuses the advantages of backpropagation artificial neural algorithm and Hu moment. with advantages of two networks and improves the speed and accuracy of identification. Finally, a hardware-in-the-loop system for UAV target automatic recognition is also developed.
Findings
The double hidden level backpropagation artificial neural can easily increase the speed of recognition process and get a good performance for recognition accuracy.
Research limitations/implications
The proposed backpropagation artificial neural algorithm can be ANN easily applied to practice and can help the design of the aircraft automatic target recognition system. The standard backpropagation algorithm has some obvious drawbacks, namely, converging slowly and falling into the local minimum point easily. In this paper, an improved algorithm based on the standard backpropagation algorithm is constructed to make the aircraft target recognition more practicable.
Originality/value
A double hidden levels backpropagation artificial neural algorithm is presented for automatic target recognition system of UAV.
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Keywords
Renato Iovine, Luigi La Spada and Lucio Vegni
– In this contribution, the aim is to present a nanoparticle device, operating in the visible regime based on the localized surface plasmon resonance (LSPR) phenomenon.
Abstract
Purpose
In this contribution, the aim is to present a nanoparticle device, operating in the visible regime based on the localized surface plasmon resonance (LSPR) phenomenon.
Design/methodology/approach
The nanoparticle electromagnetic properties are evaluated by a new analytical model and compared to the results obtained by numerical analysis.
Findings
A near-field enhancement is obtained by arranging the nanoparticles in a linear array. Analytical formulas, describing such enhancement, are presented.
Originality/value
The results demonstrate the possibility to use the proposed device for medical diagnostics and optoelectronics applications.
Details