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Taken together, recent advances in microelectromechanical systems, wireless mesh networks, digital circuits, and battery technology have made the notion of autonomous pico air vehicles viable. In this work we describe the core technologies enabling these future vehicles as well as propose two possible future platforms. We draw on recent research on high thrust density atmospheric ion thrusters, microfabricated...
This paper addresses the modeling, identification and adaptive sliding mode control for a quadrotor micro aerial vehicle. In order to obtain a compact kinematics and dynamics representation, the spatial vectors convention is used, making more efficiently the model computation by reducing the number of algebraic operations. Identification of parameters such as inertia moments, thrust and torque of...
Experimental and computational studies of the hovering performance of microcoaxial shrouded rotors were carried out. The ATI Mini Multi-Axis Force/Torque Transducer system was used to measure all six components of the force and moment. Meanwhile, numerical simulation of flow field around rotor was carried out using sliding mesh method and multiple reference frame technique by ANASYS FLUENT. The computational...
This paper presents the implementation of a Super Twisting (ST) controller for distributed formation flight based on a consensus algorithm for multi-agent systems (MAS). The equations of motion of each agent are based on the Newton- Euler approach and the navigation of each agent is distributed. For the navigation, two controllers namely, a PID algorithm and a Super Twisting algorithm, are tested...
This paper deals with monocular image-based aircraft Sense and Avoid for small UAVs. After summarizing previous results of the authors it proposes a complete solution which calculates time to closest point of approach, relative closest point of approach (CPA) and the direction of intruder at CPA. These parameters are enough to make a collision decision and design the avoidance maneuver. The applicability...
Autonomous navigation of small Unmanned Aerial Vehicles (UAVs) in cluttered environments is still a challenging problem. In this work, we present an approach based on graph slam and loop closure detection for online mapping of unknown outdoor environments using a small UAV. Here, we used an onboard front facing stereo camera as the primary sensor. The data extracted by the cameras are used by the...
Unmanned aircraft flying beyond line of sight in uncontrolled airspace need to maintain adequate separation from local inclement weather patterns for regulatory compliance and operational safety. Although commercial solutions for ‘weather avoidance’ exist, they are tailored to manned aviation and as such either lack the accuracy or the size, weight, and power (SWaP) requirements of small Unmanned...
This paper presents a study of near collision course engagements between a Cessna 172R aircraft and a ScanEagle UAV carrying a custom built vision-based sense-and- avoid system. Vision-based systems are an attractive solution for the sense-and-avoid problem because of size, weight and power considerations. We present post flight test analysis that shows our detection system successfully detecting...
The U.S. Department of Energy and Transportation considers pipeline security and the timely containment of leaks as a top priority for the oil and natural gas industry. However, despite significant investment in network sensing and maintenance, utilities still incur significant delays (and associated losses) in managing failures. This article focuses on the use of small Unmanned Aerial Systems (sUASs)...
Safety and reliability (also referred to as airworthiness) are well-known factors of Unmanned Aerial Vehicle (UAV) operations, and significant effort has been put into maintaining and improving them for everyday UAV users. Cyber-security, on the other hand, gained attention only recently. Currently, a malicious user can relatively easily disturb operation or even seize control of the most popular...
The measurements of air-to-air channel at C-band for coexistence among multiple unmanned aircraft (UA) systems are presented. The measurement campaign was performed to clarify the channel characteristic of the air-to-air radio propagation between small UAs. This paper presents a measurement result of our campaign on radio channel characteristics in C-band held in Japan in March 2016. The received...
Small unmanned aerial systems (UAS) require constant, safety-critical connectivity for telemetry, command-and- control, and collision avoidance. Today, dedicated, short-range pilot-to-aircraft links provide this connectivity for UAS operation. For UAS operating in fleets and beyond line-of-sight, a robust multi-transmitter network to provide connectivity over a wide area will be needed. However, networks...
Reliable high-speed wireless communication is essential for abundant new unmanned aircraft system's (UAS) applications. While orthogonal frequency division multiplexing (OFDM) has been widely used for wideband communications because of its efficiency and its robustness to multipath propagation, high Doppler shift of UAS channels makes the implementation of OFDM challenging for UAS applications. Doppler...
Multi-UAS (MAS) flocking requires multiple controllers with connected communication topologies. Real-time deployment of multi-agents is commonly associated with dynamic communication topologies, which has been considered as a challenging topic. This paper proposes a novel low- computation distributed connectivity control method to generate connected communication topologies and maintain the connectivity...
The work presented in this paper is part of an overall effort to design a secure autopilot, resilient against malicious attacks on both the cyber and physical layers, for a small unmanned aircraft system (UAS). This paper specifically deals with identification of malicious attacks on the sensors of a small UAS. A framework is presented wherein techniques from statistical analysis are used in a probabilistic...
Due to increasingly dense agricultural land use, many ground breeding birds are threatened with extinction or near threatened. We present a new method, to detect lapwing and other ground breeding bird nests. A small UAV with a thermal camera is suitable to detect a lapwing nest from a flight altitude of 40 m. With the aid of a special thermal camera image preprocessing algorithm the contrast could...
The ability to conduct useful science under the framework of precision agriculture is not only dependent upon the collection of high quality usable data of plants, soil, and water, but also dependent upon the type of vehicle the sensors are flown on, properly tuned sensors, and the way in which the vehicle is flown. To achieve this capability requires the proper matching and integration of air vehicle,...
This paper presents the design, development and testing of a 4-DoF aerial manipulator for bridge inspection, where the arm is placed at the upper part of the multirotor body. The manipulator joints are equipped with a compliant mechanism that allows the contact with the environment reducing the influence over the platform stability. The transmission mechanism consists of two pairs of springs and a...
The usages and functionalities of Unmanned Aerial Vehicles (UAV) have grown rapidly during the last years. They are being engaged in many types of missions, ranging from military to agriculture passing by entertainment and rescue or even delivery. Nonetheless, for being able to perform such tasks, UAVs have to navigate safely in an often dynamic and partly unknown environment. This brings many challenges...
Formation control of multi-robot system may involve extensive inter-robot information exchange. This paper proposes a methodology to reduce the frequency of information exchange in a formation control problem through the use of a self-triggered control strategy for cooperative path following (CPF) problems. In particular, a decentralized, self-triggered CPF controller is developed for fixed-wing Unmanned...
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