Ingrid Schjølberg

Small Scale Reformers for on-site Hydrogen Supply

Abstract This paper presents the major outcome of the IEA Hydrogen Implementing Agreement (IEA-HIA) Task 23 “Small-scale reforming for on-site hydrogen supply”. The task is briefly described, including the three sub-tasks: harmonized industrialization, sustainability and renewables and market information. An exclusive network of worldwide suppliers of reformers as well as gas companies has contributed to the discussion, evaluation and harmonization of on-site production technologies and optimal use of feedstock. The ambition has been to contribute to harmonization of capacities and improved system performance to facilitate both reduced system and production costs.

On the Boundedness and Skew-Symmetric Properties of the Inertia and Coriolis Matrices for Vehicle-Manipulator Systems

Abstract This paper addresses the boundedness property of the inertia matrix and the skew-symmetric property of the Coriolis matrix for vehicle-manipulator systems. These properties are widely used in Lyapunov-based stability proofs and are therefore important to identify. For example, the skew-symmetric property does not depend on the system at hand, but on the choice of parameterisation of the Coriolis matrix, which is not unique. It is the authors experience that many researchers take this assumption for granted without taking into account that there exist several parameterisations for which this is not true. In fact, most researchers refer to references that do not show this property for vehicle-manipulator systems, but for other systems such as single rigid bodies or manipulators on a fixed base. As a result, the otherwise rigorous stability proofs fall apart. In this paper we point out several references that are widely used, but that do not show this property and we refer to the correct references. As most references on this topics are not easily accessible, we also give the correct proofs for commonly used parameterisations of the Coriolis matrix and thus provide a proof for future reference. The same is the case for the boundedness property of the inertia matrix which for a bad choice of state variables will not necessarily hold. This can be solved by deriving the dynamics for vehicle-manipulator systems in terms of quasi-velocities, which allows us to describe the dynamics without the presence of the Euler angle singularities that normally arise in vehicle-manipulator dynamics. To the authors best knowledge we derive for the first time the dynamic equations with both the skew-symmetric property of the Coriolis matrix and the boundedness property of the inertia matrix for vehicle-manipulator systems with non-Euclidean joints.

Development of robotic solutions for oil/gas, aluminum and manufacturing industry

Future robotics solutions will allow for larger degree of autonomy, easy re-programming and build on sensor based control. Current state-of-the-art technologies in the field of robotics are not sufficient for automating a number of todays manual manipulation tasks. The objective of this paper is to describe the main approach of the project Next Generation Robotics for Norwegian Industry (NextGenRob), contributions and preliminary results developed so far to face the current challenges imposed to the industrial project partners whom represent oil/gas, aluminum and manufacturing industry. The project is a joint effort between industry and academia to develop enabling robotic technology and solutions. A number of demonstrators have been developed and are shortly presented in this paper.

A comparison study between artificial neural networks and AR models, applied to Norwegian inflow time series

Presents the use of artificial neural networks (ANN) and autoregressive models (AR models) as runoff models for application in the Norwegian hydro scheduling system. The main aim of the work is to investigate the performance of the different models applied to inflow time series. Improved performance of the runoff models gives better scheduling and better energy economics. The main contribution of this work is the application of these types of models in identifying daily and weekly inflow in Norwegian hydro electric power systems. The models are applied to single and multivariate systems.

RBF network pruning techniques for adaptive learning controllers

This paper presents two simple and efficient methods for pruning a Radial Basis Network (RBF) used in an adaptive controller architecture for a robotic manipulator. The methods presented in this paper are Weight Magnitude Pruning (WMP) and Node Output Pruning (NOP). The above pruning methods are simulated on a trajectory tracking task of a three degree of freedom robotic manipulator arm. The RBF based inverse dynamics controller is presented with a task of learning the inverse dynamics of the plant in a closed loop control. Simulation study shows that implementation of an inverse dynamics control law in such manner makes the controller more robust towards uncertainties and disturbances. Pruning RBF network improves controller performance in the case of modelling errors and reduces computational costs, thus making such controller more suitable for implementation.

Learning intelligent controllers for path-following skills on snake-like robots

Multi-link wheeled robots provide interesting opportunities within many areas such as inspection and maintenance of pipes or vents. A key functionality in order to perform such operations, is that the robot can follow a predefined path fast and accurately. In this paper we present an algorithm to learn the path-following behavior for a set of motion primitives. These primitives could then be used by a planner in order to construct longer paths. The algorithm is divided into two steps: an example-based stage for controller learning, and a controller tuning stage, based on an objective function and simulations of the path-following process. The path-following controllers have been tested with a simulator of a multi-link robot in several complex paths, showing an excellent performance.

DYNAMIC BEHAVIOUR OF A NOVEL SMALL-SCALE HYDROGEN REFORMER

Abstract This paper explores dynamics for control design for a novel small-scale hydrogen reformer based on compacted plated heat exchanger technology. Reforming is seen as an important step towards the use of renewable fuels as feedstock. For reforming to be competitive to electrolysis and trucked-in hydrogen, high operability and robustness is required. This is achieved through an understanding of the system dynamics and robust control structure design. The paper identifies important dynamic features of the reformer unit and focuses on the responses in the hydrogen production rate to changes in several candidate inputs. This work was part of EC project Hydrofueler.