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• #### PD+ based trajectory tracking of the underactuated quadrotor platform using dual quaternions ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-29)
We address the problem of state feedback trajectory tracking of the underactuated quadrotor platform in the dual quaternion framework through a PD+ tracking controller. The control law negates the need of generating a desired attitude trajectory as the translational error is mapped directly onto the rotational actuators through a virtual frame. More precisely, we show uniform practical asymptotic ...
• #### Interpreting teaching for conceptual and for procedural knowledge in a teaching video about linear algebra ﻿

(Journal article; Tidsskriftartikkel, 2018)
The aim of this study is to investigate teaching videos about mathematics, seeking to uncover research-based foundations for their quality. By drawing on the notions of procedural and conceptual knowledge, the research was operationalized by asking professionals in undergraduate mathematics education (n=18) to interpret sections of a teaching video. The video dealt with a topic in linear algebra. ...
• #### Charging technology for small maritime vessels ﻿

(Conference object, 2019-01-21)
• #### Engineering students' instrumental approaches to mathematics; some positive characteristics ﻿

(Journal article; Peer reviewed, 2018)
The present paper presents three deliberately chosen mathematical episodes observed in a class of engineering students taking a basic calculus course. By drawing on analyses of instrumental and relational learning strategies, the episodes are shown to illustrate instrumental approaches indicated by the students. The paper discusses positive characteristics about these approaches while further data ...
• #### Framework for Modeling and Simulation of Household Appliances ﻿

(Peer reviewed; Chapter, 2018-12-31)
This paper describes a framework for simulating household appliances in Simulink. Typical Norwegian household equipment have been analyzed based on their characteristic behavior, to establish the requirement for synthesizing and recreating their current waveform, harmonic currents and phase shift. Both detailed simulation of the current waveform and RMS currents for simulation over longer time periods ...
• #### Modeling and Attitude Control of Satellites in Elliptical Orbits ﻿

(Peer reviewed; Chapter, 2018-11-05)
The attitude determination and control system (ADCS) for spacecraft is responsible for determining its orientation using sensor measurements and then applying actuation forces to change the orientation. This chapter details the different components required for a complete attitude determination and control system for satellites moving in elliptical orbits. Specifically, the chapter details the orbital ...
• #### A Comparative Study of Different Control Structures for Flight Control with New Results ﻿

(Peer reviewed; Book; Chapter, 2018-10-24)
This paper presents several different control structures that facilitate flight control and does a comparison between them. Specifically, this paper considers command-filtered backstepping, nonlinear dynamic inversion (NDI), and a new decoupled approach that decouples the rotational and translational dynamics by estimating the higher order derivatives of the angle of attack and sideslip angle. The ...
• #### Quaternion Path-Following in Three Dimensions for a Fixed-Wing UAV Using Quaternion Blending ﻿

(Peer reviewed; Book; Chapter, 2018-10-29)
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 ...
• #### A Reliable Modular Based PV-Battery Hybrid System with Peak Shaving Capability ﻿

(Peer reviewed; Chapter, 2018)
The driving factors in emerging photovoltaic (PV) systems and battery-energy-storage systems (BESS) are highly scalable feature, modular and flexible structures with superior transformerless performance. The feasibility of Modular Multilevel Converter (MMC) to operate without overall DC-link allows the integration of PV generators and battery strings with its submodules (SMs), whereas each SM acts ...
• #### Cascaded Model Predictive Control of Grid Connected Converter with LCL Filter ﻿

(Peer reviewed; Book; Chapter, 2018-12-31)
This paper presents a control strategy for grid connected voltage source converters with LCL filter, based on a cascade of two model predictive controllers (MPC). Despite the attention MPC has received in the research community over the last years, there are still raised question about what advantages such control methods can offer, compared to existing established control strategies. The cascaded ...
• #### Framework for Modeling and Simulation of Household Appliances ﻿

(Peer reviewed; Book; Chapter, 2018-12-31)
This paper describes a framework for simulating household appliances in Simulink. Typical Norwegian household equipment have been analyzed based on their characteristic behavior, to establish the requirement for synthesizing and recreating their current waveform, harmonic currents and phase shift. Both detailed simulation of the current waveform and RMS currents for simulation over longer time periods ...
• #### Curvature Continuous Path Generation for UAVs based on Generalized Expo-Rational B-Splines ﻿

(Peer reviewed; Book; Chapter, 2018)
This paper proposes a new path-planning algorithm based on GERBS to generate curvature continuous paths. The algorithm blends between a set of local curves generating a global smooth path which also interpolates the midpoint of the curves. Numerical examples are provided which demonstrates the potential of the proposed algorithm.
• #### Dual-quaternion backstepping control for a fully-actuated rigid-body ﻿

(Peer reviewed; Book; Chapter, 2018-08-16)
In this paper dual-quaternions are used to model a fully actuated rigid-body. A backstepping-controller that solves the trajectory tracking problem is derived and proved to provide uniform asymptotical stabilization of the error dynamics. Numerical simulations are provided where the controller is compared to existing dual-quaternion tracking controllers and it is shown to have similar performance.
• #### Exploring Tensions in a Mathematical Course for Engineers utilizing a Flipped Classroom Approach ﻿

(Book; Chapter; Bok; Bokkapittel; Peer reviewed, 2017-02)
Flipped Classroom approaches to teaching are becoming increasingly popular in higher education, but there is a lack of empirical research. We present here a study performed during an engineering course for 20 students at a Norwegian university, on student appropriation towards Flipped Classroom through interviews, questionnaire, video/quiz usage statistics and classroom filming. We approach this ...
• #### Approaches to learning of linear algebra among engineering students ﻿

(Peer reviewed; Bok; Book; Bokkapittel; Chapter, 2017-02)
The present paper investigates engineering students` own descriptions of what they mean by learning of linear algebra and how they know that they have learned something. I seek to extract keywords from engineering students` descriptions of learning of this discipline by drawing on grounded theory techniques and classifying the answers in conceptual and procedural approaches. By this, both detailed ...
• #### Digitalization of the power business: How to make this work? ﻿

(Peer reviewed; Bokkapittel; Book; Bok; Chapter, 2018)
As a result of the digitalization of the power business in Norway and Europa, a lot of new possibilities and challenges arise. In 2014 an expert committee one outlined a proposal for the future grid company structure in Norway (Reiten, 2014). In addition, new technologies are being implemented in the system. Wind power, solar power, un-regulated small hydro power production, battery storage domestic ...
• #### Optical water types of the Nordic Seas and adjacent areas ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2013-05-20)
A new map of Jerlov's optical water types in the Nordic Seas and adjacent waters at 139 locations, as well as a table with statistical and geographical properties of the vertical attenuation coefficient of downward irradiance at 475 nm, are presented. The data analysis is based on 715 recordings at different stations, at latitudes between 54° and 82°N, and longitudes between 31°W and 49°E, obtained ...
• #### Når blir skipsfarten grønn? ﻿

(Kronikk; Chronicle, 2018-04-25)
n av utfordringene i forbindelse med dagens skipsfart er utslipp til luft, hovedsakelig karbondioksid og nitrogenoksider. Disse utslippene er knyttet til oljefyrte forbrenningsmotorer som dominerer dagens skipsflåte. Det er overveiende sannsynlig at det er en direkte sammenheng mellom global oppvarming og utslipp av klimagasser. Utslipp til luft kan også bidra til sur nedbør og svevestøv, for å nevne ...
• #### 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 ...
• #### Underactuated Waypoint Tracking of a Fixed-Wing UAV ﻿

(Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
In this paper a new method of performing waypoint tracking is shown for underactuated fixed-wing UAVs. The position error can be mapped onto the desired axis using a desired rotation matrix, while the velocity error can be mapped to the desired axis using a desired angular velocity. With all errors defined along one axis, the tracking problem is easily solved using only one thruster. A velocity ...