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This paper addresses the problem of autonomous navigation of a quadrotor helicopter using state estimators when the GPS signal is not available. The main objective is to estimate the translational position and velocity of the flying machine. The observer proposed uses a double integral approximation of the acceleration defined in the mathematical model in order to estimate the states previously mentioned...
The sole means for conventional multirotor UAVs to achieve horizontal translation motion is by inducing changes in vehicle attitude. The lack of horizontal force control not only disallows full controllability in all 6 Degrees of Freedom (DoFs), but also limits the set of possible control solutions. One way of achieving horizontal force control is by mounting the rotors of a UAV under a fixed amount...
This paper presents an algorithm for improving navigation performance of an Unmanned Aerial Vehicle (UAV) in GPS-challenging environments, which exploits aiding measurements from one or more cooperative UAVs flying under full GPS coverage. In particular, sensor fusion is based on an Extended Kalman Filter that integrates measurements from onboard inertial sensors and magnetometers, available GPS pseudoranges,...
In this paper, Aircraft Dynamics Model (ADM) augmentation for Remotely Piloted Aircraft System (RPAS) navigation and guidance is presented. This approach provides additional information suitable to compensate for the shortcomings of vision based navigation sensors and Micro-Electromechanical System Inertial Measurement Unit (MEMS-IMU) sensors for attitude determination tasks. The ADM virtual sensor...
For flight automation tolerable to satellite navigation dropouts, this paper presents a simultaneous localization and mapping method based on radar altimeter measurements and monocular camera images. The novelty within mapping is the combination of radar distance and image triangulation. This approach verifies whether the radar measurement fits to a specific horizontal plane in the map, yielding the...
This paper presents an implementation method for an autonomous take-off and landing with a quadcopter on a stationary platform. The altitude measurement is improved with a Lidar, an inertial unit and a Kalman filter. Equations shown for a take-off and landing path use position and velocity commands. A non linear Backsteping robust control law is used. The entire system is programmed in C/C++ with...
Modeling and identification of an aerial vehicle will allow engineers to design and implement guidance and control systems using the mathematical model acquired on flight. Using the mathematical model, several improvements and benefits shall be obtained, such as designing control subsystem using Modern Control Theory; the expected results at the workbench test will correspond more accurately to the...
Unmanned stratospheric aircraft capable of staying aloft for long periods of time have become a topic of interest in the past years. Several problems are still to be solved to allow for a profitable commercial use of such aircraft. The inherent lightweight design leads to fragile structures with low payload capacities and a high wind sensitivity. The weather dependence significantly reduces the system's...
This paper presents the combination of Potential Flow Field (PFF) and Virtual Force Field (VFF) methods to construct a viable means for UAS's to autonomously navigate and avoid collisions with obstacles. A validated flight dynamics model of a fixed-wing UAS was integrated with a heading hold autopilot that receives commanded heading angles from the selected output of the PFF and VFF methods. PFF primarily...
This paper addresses the problem of enabling Unmanned Aircraft Systems (UAS) to avoid mid-air collisions during path planning applications. We propose an improved strategy that allows the UAS to negotiate obstacles encountered during flight, while keeping the objective of finding a feasible path towards its destination. Our method computes multiple steps along the UAS's path based on GPS coordinates,...
This paper considers the problem of convoy protection missions using a fixed-wing Unmanned Aerial Vehicle (UAV) in scenarios where the radius of the circular region of interest around the convoy is smaller than the UAV minimum turning radius. Using the Moving Path Following (MPF) method, we propose a guidance algorithmic strategy where a UAV moving at constant ground speed is required to converge...
A unified approach to cooperative and non-cooperative Sense-and-Avoid (SAA) is presented that addresses the technical and regulatory challenges of Unmanned Aircraft Systems (UAS) integration into non-segregated airspace. In this paper, state-of-the-art sensor/system technologies for cooperative and non-cooperative SAA are reviewed and a reference system architecture is presented. Automated selection...
This paper introduces the reasoning and concepts behind a generic and modular approach to obstacle avoidance based on geofencing. The issue of UAV safety is tackled from a practical point of view and a collision avoidance system based on practical usage and safety considerations is presented. Before doing so, the need for a reference model of geographic geometry is discussed, looking at global positioning...
Intruder detection is a crucial problem in vision based Sense and Avoid (SAA) system. In this paper a deep feature learning based intruder detection algorithm is proposed. The intruder detection algorithm contains four parts: obtaining the test samples, creating the overcomplete dictionary, deep feature learning and determining the region of the intruder. The sliding window technique is adopted to...
A system of networked computer components is described allowing realistic simulation and performance assessment of see-and-avoid algorithms for unmanned aircraft systems (UAS). Due to its realistic physics engine and relatively open architecture, the X-Plane flight simulator is adopted to simulate computer-generated traffic or an aircraft controlled by a human pilot. Using the UDP interface in X-Plane,...
This paper presents the development of a 3D obstacle avoidance algorithm for Unmanned Aerial Vehicle (UAV) system. The avoidance algorithm works by generating avoiding waypoints, within the original predefined waypoints, when the vehicle faces obstacles obstructing its flightpath. The proposed approach bases its algorithm on the utilization of ellipsoid geometry for defining a restricted zone containing...
Sense and Avoid (SAA) has been identified as one of the crucial technologies for UAV safety flight. The SAA systematic design is to develop a system with sensor configuration and SAA algorithms. Normally, the SAA system integration and test can be both expensive and dangerous without carefully system and algorithms development. In this paper, we proposed a software based SAA simulation framework for...
In this paper, we present a novel mobile target tracking filter that incorporates delayed measurements captured by a video camera onboard a flying platform, such as Unmanned Aerial Vehicles (UAVs). A curve-fitting-based technique is developed to characterize the system state information in the past. The coefficients are obtained and updated using an Extended Kalman Filter (EKF) based technique, which...
An estimation framework is presented that improves the robustness of GPS-denied state estimation to changing environmental conditions by fusing updates from multiple view-based odometry algorithms. This allows the vehicle to utilize a suite of complementary exteroceptive sensors or sensing modalities. By estimating the vehicle states relative to a local coordinate frame collocated with an odometry...
This paper describes a vision-based multiple model adaptive estimation using UAVs that enables the tracking of a mobile target that changes the system model depending on unknown factors. In our system the machine-learning-based target identification method uses Haar-like classifiers that detects the target position. The system uses multiple extended Kalman filters for each system model and estimates...
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