Jens Glad Balchen: A Norwegian Pioneer in Engineering Cybernetics

This paper tells the story of Jens Glad Balchen (1926-2009), a Norwegian research scientist and engineer who is widely regarded as the father of Engineering Cybernetics in Norway. In 1954, he founded what would later become the Department of Automatic Control at the Norwegian Institute of Technology in Trondheim. This name was changed to the Department of Engineering Cybernetics in 1972 to reflect the broader efforts being made, not only within the purely technical disciplines, but also within biology, oceanography and medicine. Balchen established an advanced research community in cybernetics in postwar Norway, whose applications span everything from the process industry and positioning of ships to control of fish and lobster farming. He was a chief among the tribe of Norwegian cybernetics engineers and made a strong impact on his colleagues worldwide. He planted the seeds of a whole generation of Norwegian industrial companies through his efforts of seeking applications for every scientific breakthrough. His strength and his wisdom in combination with his remarkable stubbornness gave extraordinary results

Trajectory Planning and Control for Automatic Docking of ASVs with Full-Scale Experiments

We propose a method for performing automatic docking of a small autonomous surface vehicle (ASV) by interconnecting an optimization-based trajectory planner with a dynamic positioning (DP) controller for trajectory tracking. The trajectory planner provides collision-free trajectories by considering a map with static obstacles, and produces feasible trajectories through inclusion of a mathematical model of the ASV and its actuators. The DP controller tracks the time-parametrized position, velocity and acceleration produced by the trajectory planner using proportional-integral-derivative feedback with velocity and acceleration feed forward. The method's performance is tested on a small ASV in confined waters in Trondheim, Norway. The ASV performs collision-free docking maneuvers with respect to static obstacles when tracking the generated reference trajectories and achieves successful docking.Comment: 12 pages, 7 figures. Accepted to the IFAC World Congress 202

Warm-Started Optimized Trajectory Planning for ASVs

We consider warm-started optimized trajectory planning for autonomous surface vehicles (ASVs) by combining the advantages of two types of planners: an A* implementation that quickly finds the shortest piecewise linear path, and an optimal control-based trajectory planner. A nonlinear 3-degree-of-freedom underactuated model of an ASV is considered, along with an objective functional that promotes energy-efficient and readily observable maneuvers. The A* algorithm is guaranteed to find the shortest piecewise linear path to the goal position based on a uniformly decomposed map. Dynamic information is constructed and added to the A*-generated path, and provides an initial guess for warm starting the optimal control-based planner. The run time for the optimal control planner is greatly reduced by this initial guess and outputs a dynamically feasible and locally optimal trajectory.Comment: Accepted to the 12th IFAC Conference on Control Applications in Marine Systems, Robotics, and Vehicles (CAMS 2019

Trends in physical health complaints among adolescents from 2014 – 2019: Considering screen time, social media use, and physical activity

The rising rates of physical and mental health complaints among adolescents observed in many countries have coincided with an increased time spent on screen-based devices, including social media use. We sought to document recent trends in physical health complaints (PHC) and whether co-occurring trends in screen time, social media use, and physical activity may account for these trends. To achieve these aims, we used data from the nationwide Ungdata surveys conducted annually at the municipality level in Norway, comprising 419,934 adolescents aged 13–18 from six survey years (2014–2019). Six items assessed PHC, including neck and shoulder pain, headache, and abdominal pain, during the past month. To account for the nesting structure of Ungdata, and to exploit the variation within and between municipalities, we used multilevel analyses with adolescents nested in municipality-years (n = 669), nested in municipalities (n = 345). We found a small to moderate linear increase in number of PHC among boys and girls from 2014 to 2019. Screen time and social media use moderately attenuated the trend for girls, and to a lesser extent for boys. Screen time and social media use were further positively associated with PHC across the between and within-municipality levels, and social media use was more strongly associated with PHC for girls than boys across all levels of analysis. A similar pattern emerged when considering each symptom individually. The results suggest that the prevalence of PHC rose in tandem with a group-level shift towards higher screen time and social media use. Moreover, the results indicate that higher screen time and social media use may have led to changes in the youth culture with potential consequences for adolescents’ well-being.publishedVersio

Past Year Cannabis Use Among Norwegian Adolescents: Time Trends Based on the Ungdata Surveys 2010–2019

Aims: To describe trends in cannabis use from 2010 to 2019 among Norwegian adolescents and relate these to individual- and municipal-level variables. Design: Data from nationwide repeated cross-sectional surveys collected in 2010–2013 (T1), 2014–2016 (T2), and 2017–2019 (T3) were used to describe secular trends in proportions of adolescent cannabis use. Setting: Cross-sectional surveys in 410 of the total 428 municipalities of Norway. Participants: A total of 628,678 survey responses from adolescents aged ~13–19 years of age, in which 566,912 survey responses were eligible for analyses, representing data from 340 municipalities. Measurements: Respondent's past year cannabis use, time, gender, school grade, municipality, geographical location, and municipality population. Findings: Boys reported overall higher cannabis use, with ~2:1 gender ratio for any past year cannabis use and a 3:1 gender ratio for frequent cannabis use. Adolescents in Eastern Norway reported higher cannabis use compared with other areas in the country, and adolescents from municipalities with a higher population size reported higher rates of cannabis use than smaller municipalities. A gradual increase in cannabis use from T1 to T3 was found in Eastern Norway and in the largest municipalities. More generally, proportions of past year cannabis use showed a marked increase from T2 to T3 across genders, grade/age groups, geographical location, and municipality population, with few exceptions. Conclusions: Our findings indicate that proportions of past year cannabis use have increased among Norwegian adolescents in recent years. Preventive interventions to hinder initiation of cannabis use, as well as measures to address frequent cannabis use among Norwegian adolescents, are needed.publishedVersio