Perfect partial reconstructions for multiple simultaneous sources

A major focus of research in the seismic industry of the past two decades has been the acquisition and subsequent separation of seismic data using multiple sources fired simultaneously. The recently introduced method of {\it signal apparition} provides a new take on the problem by replacing the random time-shifts usually employed to encode the different sources by fully deterministic periodic time-shifts. In this paper we give a mathematical proof showing that the signal apparition method results in optimally large regions in the frequency-wavenumber space where exact separation of sources is achieved. These regions are diamond-shaped and we prove that using any other method of source encoding results in strictly smaller regions of exact separation. The results are valid for arbitrary number of sources. Numerical examples for different number of sources (three resp.~four sources) demonstrate the exact recovery of these diamond-shaped regions. The theoretical proofs' implementation in the field is illustrated by the results of a conducted field test.Comment: 16 pages, 5 figures. Expanded Section 3 with an additional numerical experiment and the results of a field test. Added reference

Optimization of a Pendulum System using Optimica and Modelica

In this paper Modelica and Optimica are used to solve two different optimal control problems for a system consisting of a pendulum and a cart. These optimizations will demonstrate that Optimica is easy to use and powerful when optimizing systems with highly non-linear dynamics. The optimal control trajectories are applied to a real pendulum and cart system, in open loop as well as in closed loop with an MPC-controller. The experiments show that optimal trajectories from Optimica together with MPC feedback is a suitable control structure when optimal transitions through non-linear dynamics are desired

Optimal Robot Control using Modelica and Optimica

In this paper, Modelica along with Optimica has been used to formulate and solve a minimum time optimization problem. The problem concerns traversing a given path with a robot in as short time possible under input constraints. Different problem reformulations are discussed that increase the chance of finding optimal solutions. This paper also discusses the use of these optimal solutions for control of industrial robots. A control structure, in which the optimal trajectories are essential, are used on an ABB IRB140B to ensure robustness for model errors and disturbances

Kamratgranskning av laborationsförberedelser i reglerteknik

Laborationer är ett frekvent återkommande inslag i kurserna vid Institutionen för Regerteknik. Laborationerna tar mycket resurser i anspråk, och det är därför viktigt att skapa förutsättningar för att studenterna skall få ut så mycket som möjligt av dem. Studenterna förväntas inför varje laboration läsa på relevanta delar av kursmaterialet, samt i vissa fall även lösa några förberedelseuppgifter. Det skriftliga förhör som traditionellt tillämpats för att testa studenternas förkunskaper inför laborationen har medfört att studenterna ofta upplevt stress inför laborationerna. För att skapa en mer positiv undervisningssituation har kamratgranskning av förkunskaper i grupp provats. Reaktionerna från studenterna och har varit mycket positiva. Våra erfarenheter är också positiva, även om vissa mindre signifikanta negativa bieffekter observerats

Optimal Tracking and Identification of Paths for Industrial Robots

This paper presents results from time-optimal path tracking for industrial robots. More specifically, three subproblems are studied and experimentally evaluated. The first is a contact-force control approach for determining the geometric robot motion, such that the tool centre point of the robot is moved according to the specification. The second problem is off-line solution of the optimisation problem describing the time-optimal path tracking problem, by using software which allows highlevel implementation and solution of optimisation problems. The third problem is robust control of the robot during real-time path tracking based on the optimisation results determined off-line. An earlier developed control structure for robust control is implemented and tested in a robot system. This paper discusses the theory behind time-optimal path tracking and presents experimental results. Both contact-force controlled path identification and real-time path tracking of the identified path are evaluated on a 6-DOF industrial robot of type IRB140 from ABB

Visual Position Tracking using Dual Quaternions with Hand-Eye Motion Constraints

In this paper a method for contour-based rigid body tracking with simultaneouscamera calibration is developed. The method works for a singleeye-in-hand camera with unknown hand-eye transformation,viewing a stationary object with unknown position. The method usesdual quaternions to express the relationship between the camera- andend-effector screws. It is shown how using the measured motion of therobot end-effector can improve the accuracy of theestimation, even if the relative position and orientation between sensorand actuator is completely unknown.The method is evaluated in simulations on images from a real-time 3D renderingsystem. The system is shown to be able to track the pose of rigid objects and changes in intrinsic camera parameters, using only rough initial values for the parameters. The method is finally validated in anexperiment using real images from a camera mounted on an industrial robot