Sökresultat

In production industry today a lot of engineering time is required to develop and maintain control applications. One part of the control applications are the state machines which typically are written in Grafcet/SFC. Several efforts have been made to extend Grafcet/SFC to achieve more effective and convenient development, e.g. by introducing hierarchical structuring, reusable sub-state machines, a

Parallel robots are generally said to be more accurate and have a smaller workspace compared to serial robots. With the Gantry-Tau robot, a parallel robot with relatively large workspace was presented. This article examines the end-effector positioning accuracy of the Gantry-Tau robot. End-effector positioning errors arising from joint positioning or modeling errors are studied. A geometric approa

A general framework for the study of robust synchronisation in large-scale networks is provided. Agents are represented as a common nominal linear time-invariant (LTI) single-input-single-output (SISO) system with simple poles on the imaginary axis, subject to LTI SISO stable multiplicative perturbations. The agents exchange information in order to achieve output-synchronisation, namely steer thei

We focus on improving resilience of cloud services (e.g., e-commerce website), when correlated or cascading failures lead to computing capacity shortage. We study how to extend the classical cloud service architecture composed of a load-balancer and replicas with a recently proposed self-adaptive paradigm called brownout. Such services are able to reduce their capacity requirements by degrading us

Analytical Multiple-Input Multiple-Output (MIMO) models are often attractive due to their low complexity when analyzing possibilities and limitations in the system. In this paper we outline a a possible dual link extension of an analytical MIMO channel model and investigate its suitability based on measurements of a dual link MIMO scenario. The extension is based on the correlation matrix distance

To fulfill increasing requirements within the manufacturing sector, highly flexible and adaptable automation systems are needed. It is desirable to have one integrated approach that stretches from the process planning phase, through the implementation phase and all the way to the phase for execution of the process control logics. One promising approach is to use the concepts of service-oriented ar

Recently, several control systems for closed-loop anesthesia have been demonstrated both in simulation and clinical studies. A set of performance measures, proposed by Varvel et al., have constituted the standard means of comparing such systems. This paper debates the adequacy of the Varvel measures, as applied to closed-loop anesthesia, and proposes an alternative set of measures. Key features o

This paper proposes a transfer function parameter identification method, applicable to SISO systems of any order. Parameter identification is posed as a (non-convex) squared output error minimization problem, numerically solved utilizing Newton-Raphson iteration with back tracking line search. Focus lies on computing the cost function gradient and Hessian with respect to the parameter vector and o

Abstract in UndeterminedRoot cause analysis (RCA) is a structured investigation of a problem to detect the causes that need to be prevented. We applied ARCA, an RCA method, to target problems of four medium-sized software companies and collected 648 causes of software engineering problems. Thereafter, we applied grounded theory to the causes to study their types and related process areas. We detec

The hypothesis of this thesis is that climate models should take structural vegetation changes that operate on interannual to centennial time scales into account in order to simulate climate change in a more realistic manner. To evaluate this hypothesis, a regional Earth System Model (ESM) has been developed, validated and applied over Europe. The model has enabled the identification of a number o

Separable Lyapunov functions play vital roles, for example, in stability analysis of large-scale systems. A Lyapunov function is called max-separable if it can be decomposed into a maximum of functions with one-dimensional arguments. Similarly, it is called sum-separable if it is a sum of such functions. In this paper it is shown that for a monotone system on a compact state space, asymptotic stab

In this paper, nonlinear model predictive control (NMPC) is applied to the start-up of a combined-cycle power plant. An object-oriented first-principle model library expressed in the high-level language Modelica has been written for the plant and used to set up the simulation and optimization models. The NMPC optimization problems are both encoded, using a high-level notation, and solved in the op

Autonomic computing was proposed as a promising solution to overcome the complexity of modern systems, which is causing management operations to become increasingly difficult for human beings. This work proposes the Adaptation Manager, a comprehensive framework to implement autonomic managers capable of pursuing some of the objectives of autonomic computing (i.e., self-optimization and self-healin

We derive an analytic solution to the problem of fixed-time trajectory generation with a quadratic cost function under velocity and acceleration constraints. This problem has a wide range of applications within motion planning. The advantage of the analytic solution compared to numerical optimization of the discretized problem is the unlimited resolution of the solution and the efficiency of the c