► Formation control is an important problem in the area of multi-agent systems. ► We have proposed a motion synchronization strategy in formation control. ► The motion synchronization can tolerate ...the effects of agents faults in formations. ► This approach guarantees the stability of the system under communication delays. ► This approach is robust prone to uncertainties and external disturbances, as well.
This paper proposes a formation control strategy for unmanned aircrafts using a virtual structure. Cross coupled sliding mode controllers are introduced to cope with uncertainties in the attitude measurement systems of the unmanned aircrafts and unmeasurable bounded external disturbances such as wind effects, and also to provide motion synchronization in the multi-agent system. This motion synchronization strategy improves the agents convergence to their desired positions, and this is useful for a multi-agent system with faulty agents.
Moreover, the proposed motion synchronization strategy is not restricted to specific communication topologies, and sufficient conditions are provided to guarantee the multi-agent system stability in the presence of communication delays. Numerical simulations are presented for a team of five unmanned aircrafts to make a pentagon formation and confirm the accepted performance of the proposed control strategy.
The success of the wilderness search and rescue missions is highly dependent on the time required to search for the lost person. The use of unmanned aerial systems may enhance search and rescue ...missions by supplying aerial support of the search process. There are unmanned aerial system–based solutions, which are capable of detecting the lost person using computer vision, infrared sensors, and detection of a mobile phone signal. The most pressing issue is reducing the cost of a search and rescue mission. Thus, to improve the efficiency of the resource utilization in wilderness search scenario, we consider the use of unmanned aerial system for both mobile phone detection and enabling Wi-Fi communication for the ground portion of the search and rescue team. Such an approach does not require specific additional tools (e.g. access point, specific user equipment) for communication, which reduces the cost and improves the scalability and coordination of the search and rescue mission. As a result, the article provides methods of searching the wilderness for a person using beacon signals from a mobile phone for two situations: when the distance to the source of emergency signals is unknown and when the distance is known. In addition, the voice transmission delay and the number of unmanned aircrafts are found to guaranty the quality of a call.
Purpose
With the increasing use of small unmanned aircrafts (SUAs), many countries have enacted laws and regulations to ensure the safe use of SUAs. However, there is a lack of industry-specific ...regulations accounting for the unique features of construction-related SUA operations. Operating SUAs in the construction industry is attributed to specific risks and challenges, which should be regulated to maximize the utility of SUAs in construction. This study, therefore, aims to develop a multi-dimensional regulatory framework for using SUAs in the construction industry.
Design/methodology/approach
A combination of quantitative and qualitative methods was used to compare seven selected national/regional SUA regulations to identify the applicability of implementing the existing regulations in construction. The interview surveys were then conducted to diagnose the challenges of construction-related SUA operations and gather interviewees' suggestions on the regulatory framework for SUA uses in construction.
Findings
The research found that some challenges of construction-related SUAs operations were not addressed in the current regulations. These challenges included the complex and time-consuming SUA operation permit, lack of regulation for special SUA operations in construction, insufficient regulatory compliance monitoring and a lack of construction-related remote pilots' training. A regulatory framework was then developed based on the findings of comparative analysis and interview surveys.
Research limitations/implications
This study mainly compared seven representative countries/regions' regulations, leading to a small sample size. Further research should be carried out to study the SUA regulations in other places, such as South Africa, South America or Middle East countries. Besides, this study's respondents to the interviews were primarily concentrated in Hong Kong, which may cause the interview results to differ from the construction industry in other countries/regions. A large-scale interview survey should be conducted in other places in the future to validate the current findings.
Practical implications
The proposed regulatory framework provides a reference for the policy-makers to formulate appropriate industry-specific SUA regulations and improve the applicability of SUA regulations in the construction industry. It sheds light upon the future of SUA regulations and the development of regulatory practice in this area.
Originality/value
This study is the first to propose a multi-dimensional regulatory framework for operating SUAs in construction by comprehensive policy comparisons and interviews. The regulatory framework offers a fresh insight into the unexplored research area and points out the direction for subsequent studies on SUA regulations in the construction industry.
From the previous time, unmanned aircrafts (drones) are being used in fields such as agriculture, logistics, and disaster response. Therefore, it is expected as a machine that creates new ...technologies and services in the 4th Industrial Revolution. In recent years, there has been a demand for the practical application of drones equipped with a fuel cell as a power source, which enables longer-distance flight. However, in order to operate a fuel cell drone, it is necessary to develop a protector that protects the high-pressure hydrogen tank from the impact of a crash. Therefore, the authors focused on carbon fiber as a protector for hydrogen tanks. Then, in this research, protectors for hydrogen tanks with 6 different layers and weaves were manufactured. And collision tests of these protectors were performed. Based on results obtained in collision tests, energy absorption qualities of protectors were compared and evaluated. As a result, it was clarified that the quality of energy absorption varies depending on the specifications, such as the direction of fibers and the presence or absence of plain weave sheets, even in protectors made from carbon fiber. In particular, the authors clarified the following. In the case of the Carbon Fiber Uni Direction (CFUD) sheet, in which the directional angle of the fibers is the same as the directional angle of the wedge-shaped projections or an angle with a small difference (90 degrees or 72 degrees)., the energy absorption of the protector made of this sheet alone is not good. In addition, a composite sheet that combines a CFUD sheet and a plain weave sheet has better energy absorption than a plain weave sheet alone. After clarifying the foregoing, the authors evaluated protectors with a three-stage evaluation test based on the guideline of the Ministry of Economy, Trade and Industry. Then, it was confirmed that the "Safety requirements for high-pressure hydrogen gas storage containers (tanks) to be mounted on drones" were satisfied by equipped carbon fiber protectors.
The development of unmanned aircraft system, regardless of its purpose and structural affiliation, involves the concerted efforts of stakeholders (management, scientists and designers, specialists of ...test complexes, tutors, as well as theoretical and practical instructors for operators of aircraft and their payloads control) to improve the technical characteristics and functionality of unmanned aircraft, as well as to create appropriate competencies among the personnel of operating units. It is obvious that all these measures can be fully implemented within the framework of special centers for unmanned aircraft systems of state or departmental level.
Ultracompact (~300 g) fluorescence LIDAR is developed to be installed on a small drone for remote sensing of agricultural fields. The LIDAR is based on a diode laser (405 nm, 150 mW) and a mini ...spectrometer allows reducing the device sizes and power consumptions for its placing on small aircraft drones. For field testing, the LIDAR was placed on a quadcopter for remote sensing of plants in maize field. Field testes proved the feasibility and perspectives of autonomous LIDAR sensing from drones for early detection and field locations with plants under stress.
Unmanned aerial vehicles (UAVs) are well suited for infrared (IR) thermography of solar photovoltaics (PV). For an autonomous UAV system, precise and accurate navigation is vital for data quality and ...acquisition efficiency. The navigation system of a UAV is typically based on a flight controller (FC) using global navigation satellite systems (GNSS), barometric altimeter and inertial navigation. In this paper, position estimates from an integrated FC are compared with a standalone high-performance real time kinematic (RTK) navigation system and modelled for IR fault classification scenarios. The results show that position estimation errors have a strong impact on IR image resolution and data acquisition efficiency. These results are important to consider when assessing cost effective autonomous IR inspection of large PV plants.
U današnje je vrijeme sve češća upotreba bespilotnih letjelica u mjerne svrhe. Veličina bespilotne letjelice često je proporcionalna cijeni i nosivosti. Letjelice nosivosti 2–3 kg, koliko je potrebno ...da se u zrak podigne DSLR kamera i objektiv te stabilizator kamere (engl. gimbal), višeg su cjenovnog razreda (>50000 kn). Takve letjelice imaju svoja ograničenja u zakonskim okvirima, ali i praktična ograničenja zbog svoje veličine. Razvojem autonomnih kamera malih dimenzija, kao što su akcijske kamere, pojavila se mogućnost korištenja jeftinijih, manjih te bespilotnih letjelica manje nosivosti u fotogrametrijske svrhe. Naravno, kako bi se takva kamera mogla koristiti u mjerne svrhe potrebno je prije svega provesti adekvatnu metodu kalibracije te definirati elemente unutarnje orijentacije kamere. Važno je naglasiti kako je geometrijska kalibracija, odnosno eliminacija geometrijskih pogrešaka u preslikavanju, ključan preduvjet u stvaranju idealizirane snimke, tj. snimke stvarnog optičkog preslikavanja. U ovom radu provedeno je ispitivanje kvalitete preslikanog sadržaja na snimke s ciljem ispitivanja mogućnosti korištenja akcijskih kamera u mjerne svrhe. Istraživanje se temelji na objektivnim pokazateljima kao što su globalni statistički parametri kvalitete snimki i modulacijska prijenosna funkcija te vizualna analiza snimki testnog polja. Za potrebe rada razvijeno je i po prvi puta korišteno modificirano testno polje temeljeno na normi ISO 12233.
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