Eager Evaluation Considered Harmful

In real-time systems potentially unbounded loops and lazy (late) evaluation are often avoided in order to improve predictability. This paper will show that a commonly suggested way to implement semaphores can lead to unnecessary blocking of high-priority tasks. It also presents a scheme with lazy evaluation and (potentially) unbounded loops that gives less blocking of high-priority tasks

A parametric approach to data cleaning of ion current measurements

In this thesis, a few possible methods to clean nuisance signals from ion current measurements are explored. Ion current measurements can be used to optimise a combustion engine, but interference from the ignition system coupled with clipping caused by limitations in the measurement equipment limit the amount of data that can be extracted. This thesis develops a model which is used for simulation of the ion current measurements, that is then used to construct an algorithm to remove the interference. The algorithm developed uses a parametric approach as the interference has a distinct structure that can be exploited. A corner stone of the developed algorithm is the HTLS-algorithm, which estimates frequency and damping coefficients of uniformly sampled data. The thesis implements a recursive HTLS to exploit the structure of the interference efficiently. This method performs well on simulated data, but testing on real data shows that it needs further refinement if it is to be used commercially.Vägtrafiken står för en betydande del av Sveriges utsläpp av växthusgaser och varje dag gör Sverige kollektivt motsvarande över 230 resor tur och retur till månen längs vägarna. En ökad efterfrågan på miljövänliga transportmedel har satt press på biltillverkare att ta fram bränslesnåla bilar. Det här exjobbet har tittat på ett sätt att öka mängden information som kan utläsas från förbränningsmotorer. Den här informationen kan sedan ligga till grund för en effektivare kontroll av motorerna. Forskningsvärlden är överens; vi måste minska utsläppen av växthusgaser. En stor efterfrågan på bränslesnåla bilar har uppkommit som ett svar på stegrande bränslepriser och en ökad miljömedvetenhet. Biltillverkare lägger därför stora summor på att utveckla motorer som drar mindre bränsle än sina föregångare. För att uppnå detta finns det i moderna bilar mycket avancerade system som ansvarar för att se till att bränslet används på ett effektivt sätt. För att dessa system ska kunna fatta korrekta beslut krävs det att de har tillgång till information om motorns status. Informationen mäts på olika sätt och detta arbete har tittat på en av metoderna. Informationen som kan utvinnas genom dessa mätningar har potential att kunna komma till stor användning. Problemet med dessa mätningarn är att de lider av störsignaler. Detta arbete har därför undersökt metoder för att ta bort dessa störsignaler. Störsignalerna orsakar problem på två sätt, genom att data försvinner samt eftersom störsignalen är stark i förhållande till informationen. Att data försvinner går tyvärr inte att göra något åt, den är förlorad. Men eftersom störsignalen har en tydlig struktur, går det att utnyttja detta för att plocka fram informationen ur mätdatan. Situationen går att likna vid att viska i ett rum där radion skrålar sommardängan ”Despacito” för fullt, allt vi kan höra är den senaste hitmusiken, men inte viskningen. Men eftersom hitlåtarna är välkända, räcker det med att ta reda på vilken som spelas just nu för att kunna ta bort den ur mätningen vi gör i rummet. Metoden som utvecklats har visat sig vara effektiv på så sätt att vi lyckas känna igen den metaforiska hitlåten. Det har dock visat sig att andra effekter tillkommer som inte tas i beaktning av metoden, vi kan till exempel tänka oss att rummet ekar. Viskningen är inte tillräckligt stark för att orsaka eko, men det är däremot musiken. När vi känt igen musiken kan vi därför plocka bort låten, men ekot är kvar i mätningen. Den riktiga mätdatan innehåller inga ekon på det sätt som beskrivs ovan, men det sker en förvrängning av störsignalen. Detta gör att metoden som utvecklats har problem med att utvinna all tillgänglig information. Metoden som tagits fram fungerar bra på delar av mätsignalen och lyckas i dessa delar ta fram bra information. Problemet uppstår i de delar av signalen där störsignalen blivit skev. För att kunna vidareutveckla metoden krävs undersökningar av hur denna skevhet uppkommer och hur den påverkar signalen. Kunskapen om förvrängningen bör sedan kunna arbetas in i metoden för att kunna utvinna mer information ur mätsignalen och på så sätt bygga effektivare motorer

Laboratories and Real-Time Computing

The paper describes the approach used at the Department of Automatic Control at Lund Institute of Technology to maintain a high level of practical laboratory experiments. The Department integrates laboratory experiments into its control courses. If the laboratory exercises are properly organized and the student volume is sufficiently large, it is possible to combine a high level of practical laboratory experiments in control education at a reasonable cost. The use of off-the-shelf hardware and open-source software are important, With desktop processes, it is possible to achieve high utilization of lab space and high student throughput

Flexible application development and high-performance motion control based on external sensing and reconfiguration of ABB industrial robot controllers

New robot applications increasingly require external sensing to accomplish robustness and performance despite the variations and uncertainties that come with the increasing demands on flexibility for manufacturing of customized products. The demands on productivity then require high performance, which for well known feedback-control reasons means short response times from external process event to reaction on the robot motor control. The need for high- performance sensor interfaces connected to the motion control without excessive buffering and computations has therefore gained increasing attention over the last decade. Apart from high sampling frequencies and short latencies, there are also engineering aspects to consider. Control engineering tools should be possible to utilize, additional computing power is better connected via real-time Ethernet connections, and all interfaces should check compatibility without sacrificing performance. Furthermore, all that should preferably coexist with the original system, superimposing the effects on external sensing while still maintaining safety and consistency of data. The reason is that the original control software is model based and built on millions of lines of C-code, and tested beyond the possibilities of a research lab. Such a system has been accomplished for control and application development using ABB robots. A short description of the system is given, and its use for application/control development is exemplified. User specific feedback control can be done easily with short sampling periods and less than 1ms of latency from sensing to motor reaction

Garbage collector interface

The purpose of the presented garbage collector interface is to provide a universal interface for many different implementations of garbage collectors. This is to simplify the integration and exchange of garbage collectors, but also to support incremental, non-conservative, and thread safe implementations. Due to the complexity of the interface, it is aimed at code generators and preprocessors. Experiences from ongoing implementations indicate that the garbage collector interface successfully provides the necessary functionality in an efficient way

Extending an industrial root controller : implementation and applications of a fast open sensor interface

An overview is given of the design and implementation of a platform for fast external sensor integration in an industrial robot system called ABB S4CPlus. As an application and motivating example, the implementation of force-controlled grinding and deburring within the AUTOFETT-project is discussed. Experiences from industrial usage of the fully developed prototype confirms the appropriateness of the design choices, thus also confirming the fact that control and software need to be tightly integrated. The new sensor can be used for the prototyping and development of a wide variety of new application

On the Integration of Skilled Robot Motions for Productivity in Manufacturing

Robots used in manufacturing today are tailored to their tasks by system integration based on expert knowledge concerning both production and machine control. For upcoming new generations of even more flexible robot solutions, in applications such as dexterous assembly, the robot setup and programming gets even more challenging. Reuse of solutions in terms of parameters, controls, process tuning, and of software modules in general then gets increasingly important. There has been valuable progress within reuse of automation solutions when machines comply with standards and behave according to nominal models. However, more flexible robots with sensor-based manipulation skills and congnitive functions for human inteaction are far too complex to manage, and solutions are rarely reusable since knowledge is either implicit in imperative software or not captured in machine readable form. We propose techniques that build on existing knowledge by converting structured data into an RDF-based knowledge base. By enhancements of industrial control systems and available engineering tools, such knowledge can be gradually extended as part of the interaction during the definition of the robot task

Robots in machining

Robotic machining centers offer diverse advantages: large operation reach with large reorientation capability, and a low cost, to name a few. Many challenges have slowed down the adoption or sometimes inhibited the use of robots for machining tasks. This paper deals with the current usage and status of robots in machining, as well as the necessary modelling and identification for enabling optimization, process planning and process control. Recent research addressing deburring, milling, incremental forming, polishing or thin wall machining is presented. We discuss various processes in which robots need to deal with significant process forces while fulfilling their machining task