Now showing items 1-10 of 28
Cascade-Based Controlled Attitude Synchronization and Tracking of Spacecraft in Leader-Follower Formation
(Journal article; Peer reviewed; Tidsskriftartikkel, 2011)
Subsumption architecture applied to flight control using composite rotations
(Peer reviewed; Tidsskriftartikkel; Journal article, 2016-03-19)
In this paper the subsumption theory is applied to flight control through composite rotations where multiple tasks can be defined as simple rotations. The tasks can then be arranged as a hierarchy, where the primary task is always fully pursued, and conflicting lower level tasks are removed by the primary rotation. The concept is applied to a group of uavs that move through an urban terrain while ...
Thyristor based short circuit current injection in isolated grids
(Peer reviewed; Chapter; Bokkapittel, 2017-02-16)
This paper proposes a thyristor based short circuit current injector for providing short circuit current in isolated and weak grids, where sufficient fault current to trigger circuit breakers may not be available. This will allow the use of conventional miniature circuit breakers, which requires high fault current for instantaneous tripping. The method has been validated through experiments.
Quadrotor attitude estimation using adaptive fading multiplicative EKF
(Peer reviewed; Conference object; Konferansebidrag, 2017-07-03)
This paper presents the implementation of an adaptive fading multiplicative extended Kalman filter (AFMEKF), applied to the problem of attitude estimation in the context of quadrotors. The extended Kalman filter is adapted for use with quaternions and made adaptive to account for inaccurate measurement information. Simulations have been conducted in order to validate the filter performance.
A Decoupled Approach for Flight Control
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
A decoupling method for flight control is presented that greatly simplifies the controller design. By approximating the higher order derivatives of the angle of attack and sideslip, it enables a rotation controller and a speed controller to be derived independently of each other, and thus gives access to a vast number of controller solutions derived for general classes of rotational and translational ...
Real-Time Particle Tracking using a Formation of UAVs
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
In this paper the problem of real-time particle tracking is studied. Using sensor measurements, a formation of UAVs autonomously find the closest point with high particle density where they enter a holding pattern. After converging to the holding pattern, one UAV will remain, while the rest will go looking for other maxima. To avoid collisions between the UAVs during the mission, a controller is ...
Quaternion guidance and control of quadrotor
(Peer reviewed; Conference object; Konferansebidrag; Bokkapittel; Chapter, 2017-07-27)
This paper addresses the problem of trajectory tracking for underactuated quadrotors. A quaternion based guidance law is proposed which feeds into an attitude control system based on a PD+ control law. The desired attitude from the guidance law is defined such that the attitude control system tries to align the position error along the axis of the translational actuator. Simulation results are ...
Path-following in three dimensions using quaternions for a fixed-wing UAV
(Peer reviewed; Conference object; Konferansebidrag; Bokkapittel; Chapter, 2017-08-08)
This paper presents a three dimensional guidance strategy for fixed-wing UAVs using quaternions. The algorithm is based on constructing two quaternions, one which makes the UAV fly towards the path and one that makes the UAV follow the path. These two quaternions are then blended together such that the path-following objective is reached. The guidance algorithm is applied to a simple kinematic model ...
Estimation of upward radiances and reflectances at the surface of the sea from above-surface measurements
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-02)
During 4 field days in the years 2009–2011, 22 data sets of measurements were collected in the inner Oslofjord, Norway. The data consist of recordings of spectral nadir radiances in air and water as well as spectral downward irradiance in air. The studied wavelengths are 351, 400, 413, 443, 490, 510, 560, 620, 665, 681, 709 and 754 nm. The water-leaving radiance and the reflected radiance at the ...
Experimental study of relative permittivity of atmospheric ice
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013-01-01)
Atmospheric icing on onshore and offshore structures is problematic, if we don’t detect and remove it. Despite of various ice detection techniques, capacitor based ice sensing technique is interesting one, as it is based on dielectric properties of material. This technique of measuring icing event is simple and cost- effective. Based on the dielectric concept, an experi mental ...