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Visual odometry approaches have demonstrated to work very well for localization in GPS-denied areas, however they could quickly diverge depending on the environment. In order to achieve reliable long-term localization, it is a good practice to complement vision-based estimations with an additional source of information able to correct odometry drifts. This paper presents an approach that complements...
Loading wide baseline multi-arrays optical sensor system enables a UAV to obtain large field of view and multi-view information, and maximize its detection performance. An accurate calibration is a necessary prerequisite. Since the key problem on the calibration of multi-array optical system is how to find the accurate extrinsic parameters of single array, we propose a cooperative calibration with...
We propose to estimate steady and turbulent wind velocities and aerodynamic coefficients of a fixed-wing Unmanned Aerial Vehicle (UAV) by using frequency separation as well as kinematic, aerodynamic and wind models combined in an Extended Kalman Filter (EKF). With these estimates it is possible to calculate the angle of attack and the magnitude of the airspeed. Avoiding the need for prior knowledge...
This paper addresses the problem of navigating an Unmanned Aerial Vehicle in an environment where GPS quality is degraded or lost. A method is described to return the aircraft from the GPS-degraded region to its launch point by means of visual navigation techniques. We record a string of overlapping images, or keyframes, on the outbound flight. On the return journey, a control law based on the homography...
A simple strategy to saturate the reference velocities when guiding an Unmanned Aerial Vehicle (UAV) to accomplish trajectory-tracking tasks is proposed. Such a controller has two parts: a kinematic controller to generate reference velocities for the vehicle and a state-variables change with a PD controller to guarantee the tracking of such velocities. This characterizes a cascade controller and guarantees...
This paper presents customized techniques for autonomous localization and mapping of micro Unmanned Aerial Vehicles flying in complex environments, e.g. unexplored, full of obstacles, GPS challenging or denied. The proposed algorithms are aimed at 2D environments and are based on the integration of 3D data, i.e. point clouds acquired by means of a laser scanner (LIDAR), and inertial data given by...
This paper describes vision-based target state estimation approaches for autonomous landing on a moving ground target. The state of moving ground target is estimated by using vision information from a gimbaled camera on an Unmanned Aerial Vehicle (UAV). Using the information from vision system, the UAV estimates the state of a moving target on the ground using the Unscented Kalman Filter (UKF). In...
This paper presents a novel human robot interaction system that can be used for real-time 3D environment exploration with an unmanned aerial vehicle (UAV). The method creates a mixed reality environment, in which a user can interactively control a UAV and visualize the exploration data in real-time. The method uses a combination of affordable sensors, and transforms the control and viewing space from...
This paper proposes an autonomous flight control method of quadrotor helicopter using only single Web camera. Recently, great attentions have been paid to the autonomous flight control method of quadrotor helicopter. In the previously proposed methods, for example, GPS, motion capture system and laser range finder are often applied to measure the position and posture of quadrotor helicopter. But,...
This paper presents linear system identification results using noisy data from a six-degree-of-freedom aircraft simulation and data obtained from flight test of an Unmanned Aerial System using the recently developed novel Artificial Neural Network System Identification algorithm. The method uses an artificial neural network with a single input layer and single output layer to learn the elements of...
In this paper, the hybrid fuzzy-PID controller for a coaxial rotor helicopter is developed as a supplement to the conventional PID controller. The coaxial rotor helicopter uses one motor and two swash plates linked to each other. The helicopter system is modeled by nonlinear dynamics. The PID control system works well with a moderate velocity change. However, it provides unsatisfactory performance...
This paper investigates the rejection of wind disturbances of an Unmanned Aerial Vehicle (UAV). UAVs are used for increasingly complex operations that require a great deal of accuracy and minimal position changes. This calls for better disturbance rejection. The drag-inclusive dynamics of a quadcopter are derived and used to create two uniaxial wind disturbance rejection controllers: a disturbance...
Conventional quadrotor UAVs have crucial underactuation limitations. This appears in the coupling between the roll angle and the movement in y-direction, and between the pitch angle and the movement in x-direction. The quadrotor capability of hovering with either roll or pitch angle is restricted due to these limitations. In this paper, a novel design modification is proposed in order to increase...
In this paper, a robust altitude control scheme is proposed for a mini-Quadrotor UAV system based on sliding mode controller with an integral action to eliminate the steady-state error induced by the boundary layer in order to achieve asymptotic convergence to the desired altitude with continuous control input. The proposed integral sliding mode controller is chosen to ensure the stability and robustness...
In this paper, we investigate the problem of the dynamics of a quadrotor unmanned aerial vehicle undergoing impact with its environment. This work is motivated by the fact that operation of UAVs (manual or autonomous) carries with it a significant risk of collision with surrounding objects, particularly in unknown, unstructured environments. To make small UAVs more viable and expand their autonomy,...
This paper examines the capability of a miniaturized radar sensor developed for micro Unmanned Aerial Systems (UAS) to assist the flying platform with autonomous navigation, sense-and-avoid (SAA), and imaging functions. An ultralight radar sensor based on Frequency Modulated Continuous Wave (FMCW) technology and developed by IMST GmbH is tested and results of acquired data for navigation, SAA, and...
In this paper we propose a model of zero-sum differential games (ZSG) to perform the formation flight of a group of three fixed-wing Unmanned Aerial Vehicles (UAVs). The dynamics of these UAVs are described in the linearized model around nominal values. For the formation strategy, the game scheme for one of the UAVs acts as the leader vehicle following a freely designed trajectory meanwhile the two...
Time-domain aircraft system identification is applied to flight test data obtained using a motion capture system. Longitudinal aerodynamic force and moment time histories are obtained using the estimation-before-modeling approach, in which forces and moments are modeled as Gauss-Markov processes and estimated concurrently with the aircraft state histories using an extended Kalman filter. Quasi-steady...
Multi-rotor air vehicles are controlled by varying the rotor speeds. The variation of the rotor speeds enable the altitude change, yaw motion as well as pitch and roll motions of the vehicle. Pitch and roll motion leads to translation motions along x and y axes. When the air vehicle is used for surveillance type missions, the tilting of the vehicle is not desired, since the camera will also be tilted...
To accelerate research and development of the autonomous capabilities of micro aerial vehicles we have developed flight control framework, ROSflight, as a research tool. ROSflight makes development of autopilot code easier and more efficient by minimizing the use of embedded systems, incorporating the Robot Operating System and using off-the-shelf and open-source hardware and software. Motivation...
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