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Strictly Positive Real Systems Based on Reduced-Order Observers

We study the extension of the class of linear time-invariant open-loop systems that may be transformed into SPR systems introducing a reduced-order observer. It is shown that for open-loop stable systems a cascaded observer achieves the result. For open-loop unstable systems observer-based feedback is required to succeed. In general, any stabilizable and observable system may be transformed into a

A Velocity Estimator relying on Friction Observers: Application to inverted pendulum stabilization

This paper addresses the problem of velocity reconstruction of robotic systems with rigid-body dynamics subject to friction. The aim of this paper is to estimate the velocities in the joint of a robot as well as the friction interacting with these velocities. Confronted with friction phenomena interacting with velocity dynamics, we have developed a non-linear observer, partly model-based for estim

Lacking structures of communication for teachers in Sweden, a focus group study

In light of the changing circumstances for teaching, teachers’ views on organizational communication processes were explored. Empirically, this paper is based on five semi-structured focus groups, each interviewed on two occasions. In total, 44 primary and lower secondary-school teachers working in one municipality in Sweden participated. The interviews were framed by a pre-survey concerning demog

The aerobic diagenesis of Mesoproterozoic organic matter

The Xiamaling Formation in the North China Block contains a well-preserved 1400 Ma sedimentary sequence with a low degree of thermal maturity. Previous studies have confirmed the dynamic and complex nature of this evolving marine setting, including the existence of an oxygen-minimum zone, using multi-proxy approaches, including iron speciation, trace metal dynamics, and organic geochemistry. Here,

Explicit Form of Lyapunov Functions for a Class of Nonlinear Feedback Systems Augmented with Observers

The paper suggests conditions for presence of quadratic Lyapunov functions for nonlinear observer based feedback systems with an 'input nonlinearity' in the feedback path. Provided that the system using state feedback satisfies the Circle Criterion (i.e., when all states can be measured), we show that the extended system with only output feedback control from a (full state) Luenberger-type observe

Friction Compensation Based on LuGre Model

We consider a tracking problem for mechanical systems. It is assumed that feedback controller is designed neglecting some disturbances, which could be approximately modeled by a dynamic LuGre friction model. We are interested to derive an additive observer-based compensator to annihilate or reduce the influence of such a disturbance. We exploit a recently suggested approach for observer design for

Generalized Contact Force Estimator for a Robot Manipulator

In this work, we present implementation and experiment of the theory of dynamic force sensing for robotic manipulators. Since the inertial forces are undesirable forces to be measured in the robot manipulation, it is processed, using sensor fusion techniques, the force sensor signal in order to extract the contact force exerted by the robot. We propose a complete formulation and implementation of

Generating Stable Propeller Motions for Devil Stick

The theory for motion planning and feedback stabilization of periodic orbits has regained a large interest during the last couple of years, with applications in, for instance, biped locomotion. The analysis of zero-dynamics after partial feedback linearization has been one means. More recently, the introduction of virtual holonomic constraints has offered also the design tools for these type of sy

Wrestlers, Fans and Power Dynamics at Live Events

Within the world of professional wrestling, the blurred boundaries of the live event and physical nature of the sport intersect with the dramatized storytelling of this entertainment experience. As such, this chapter considers how audiences and fans interact with professional performers to co-produce the cultural practices of professional wrestling. The author uses ethnographic research at live pr

Stable Periodic Motions of the Pendubot via Virtual Holonomic Constraints

This paper presents a new control strategy for an underactuated two-link robot, called the Pendubot. The goal is to create stable oscillations of the outer link of the pendubot, which is not directly actuated. We exploit a recently proposed feedback control design strategy, based on motion planning via virtual holonomic constraints. This strategy is shown to be useful for design of regulators for

Resursanvändning och samverkan mellan skola och socialtjänst vid barnavårdsutredningar : En modell för beräkningar av tid, kostnader och samverkan

Under hösten 2017 och våren 2018 genomförde innovationsenheten PART – Preventivt arbete tillsammans– och Institutionen för service management och tjänstevetenskap vid Lunds universitet ett utvecklingsarbete,med syftet att ta fram en modell för att öka kunskapen om resursanvändning i barnavårdsutredningar. Måletmed den framtagna modellen är att göra det möjligt att kartlägga arbetsuppgifter och tid

Maktkamp delar Egyptens vänster

Har den egyptiska revolutionen nått sin slutstation eller kommer de närmaste dagarna att erbjuda överraskande nya vägar framåt?

Determination of Cooking Degree of Boiled and Steam Cooked Poatoes (Solanum tuberosum L.) from Physico-Chemical and Sensorial Perspective

Potatoes served in large-scale food service systems are often of poor quality. The current recommendation is to cook the potatoes until the core has reached a temperature of 96°C, but this recommendation is questionable. In this study, three potato varieties have been cooked by using conventional boiling (CB) to temperatures of 94°C and 96°C and steam cooking (SC) to temperatures of 92°C, 94°C and

PaddyCheck—An Instrument for Rice Quality Determination

Several of the rice quality parameters are nowadays determined manually or partly manually, which leads to subjective results. In order to analyse the rice quality and avoid most of the manual handling, the PaddyCheck instrument was mainly developed to measure the paddy/rough rice kernels. However, the design and technique of the instrument are also suitable for brown rice kernels. The PaddyCheck