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  • 51. Johansson, Sven
    et al.
    Håkansson, Lars
    Persson, Per
    Claesson, Ingvar
    THE MULTIPLE-INPUT/SINGLE-OUTPUT FEEDFORWARD CONTROL OF LATERAL VIBRATION IN A HIGH-SPEED TRAIN CAR2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    The problem of low- frequency lateral train-car vibration is an important issue surrounding the design of high-speed trains. Passive solutions such as stiffening the car chassis are impractical because of the weight increase. Semi-passive solutions, such as modifying the structural dynamics of the carboy through non-rigid coupling of heavy underfloor equipment does not come with a weight penalty, but do not sufficiently reduce the vibrations. However, computer simulations based on signals derived from a dynamic computer model of a train car indicates that the incorporation of a feedforward active control system, is likely to introduce a substantial reduction in the lateral vibration level. A simple controller structure is used and it is based on the multiple- input/single-output filtered-x LMS algorithm. Active control results illustrate an attenuation of the lateral train-car vibration by up to 14 dB.

  • 52. Johansson, Sven
    et al.
    Håkansson, Lars
    Persson, Per
    Claesson, Ingvar
    The Multiple-input/Single-output Feedforward Control of Lateral Vibration in a High-speed Train Car2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    The problem of low- frequency lateral train-car vibration is an important issue surrounding the design of high-speed trains. Passive solutions such as stiffening the car chassis are impractical because of the weight increase. Semi-passive solutions, such as modifying the structural dynamics of the carboy through non-rigid coupling of heavy underfloor equipment does not come with a weight penalty, but do not sufficiently reduce the vibrations. However, computer simulations based on signals derived from a dynamic computer model of a train car indicates that the incorporation of a feedforward active control system, is likely to introduce a substantial reduction in the lateral vibration level. A simple controller structure is used and it is based on the multiple- input/single-output filtered-x LMS algorithm. Active control results illustrate an attenuation of the lateral train-car vibration by up to 14 dB.

  • 53.
    Khan, Imran
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Claesson, Lena
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Performing active noise control and acoustic experiments using real test setup via the Internet2016Ingår i: Proceedings of 2016 13th International Conference on Remote Engineering and Virtual Instrumentation, REV 2016, IEEE Press, 2016, s. 375-376Konferensbidrag (Refereegranskat)
    Abstract [en]

    In In this demo session, it will be shown how to perform Active Noise Control (ANC) and various important Acoustic experiments remotely on the remotely controlled ANC laboratory developed by Blekinge Institute of Technology, Sweden. An important consideration in ANC is the active control’s performance dependence on the spatial position of the reference and error sensors, etc. This will be highlighted particularly. This feature is recently implemented using stepper motors which can be controlled via the Internet. It will be demonstrated how to write and upload active noise control algorithms e.g. Filtered-X Least Mean Square (FXLMS) to a digital signal processors (DSP) board. For the acoustic experiments various interesting acoustic properties such as waveforms, speed of sound, mode shapes and sound pressure spectra may be measured. A short guide about the measurements and PowerPoint presentation will be provided during the demo to facilitate for the users. The Lab setup and the equipment will be shown to the user using Skype and a web camera.

  • 54.
    Khan, Imran
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Gertsovich, Irina
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Claesson, Ingvar
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Johansson, Per-Erik
    Wirenstedt, Maria
    Borja, Oscar
    Petersson, Stefan
    MRI SCANNER VIBRATION PATH ANALYSIS2013Ingår i: Machinery Noise and Vibration, 2013, artikel-id 725Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Magnetic Resonance Imaging (MRI) scanner is one of the most important tools in clinical diagnostics. MRI scanners are associated by strong vibration which results in unpleasant and disturbing acoustic noise. The primary source of this vibration is the Lorentz force produced by fast switching of the currents inside the gradient coils of MRI scanners under a strong static magnetic field. During an MR-imaging scan the switching is controlled in order to spatially code the hydrogen nuclei that will generate the signal, which is reconstructed into anatomical images. Faster switching of the currents allows for shorter scan times and/or higher image resolutions. Consequently, the clinical quality has motivated the drive for shorter switching time and higher currents. This development, however, has also caused an undesired increase of MRI vibrations. The overall vibration phenomenon of an installed fully functional MRI scanner system becomes unique because of the installed location and ambiance. This vibration can potentially degrade the image quality and hence the diagnosis. Apart from the vibration produced, the associated annoying acoustic noise may not only affect the patients under examination and the clinical staff, but may also be transmitted to other parts of the building and causing discomfort for the personnel working there. In order to devise an effective isolation plan or improve an existing one both for vibration and acoustic noise it is important to study the noise and vibration transfer paths. This paper concerns an investigation of vibration transfer paths for vibration excited by an installed functional MRI scanner at a medical facility. The vibration transfer paths have been investigated experimentally. The obtained results are presented and discussed.

  • 55.
    Khan, Imran
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Maciej, Z.
    Konopka, P.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    REMOTE CONTROL OF ACTIVE NOISECONTROL AND AOCUSTICS EXPERIMENT SETUP VIA THE INTERNET2014Konferensbidrag (Övrigt vetenskapligt)
  • 56.
    Khan, Imran
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Moazzam, M
    Rabbani, S.M.
    Johansson, Sven
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    PERFORMANCE EVALUATION OF CONTROL ALGORITHMS IMPLEMENTED ON A REMOTELY CONTROLLEDACTIVE NOISE CONTROL LABORATORY2013Konferensbidrag (Övrigt vetenskapligt)
  • 57.
    Khan, Imran
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Muhammad, Moazzam
    Rabbani, Muhammad Shoaib
    BTH.
    Johansson, Sven
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Performance evaluation of control algorithms implemented on a remotely controlled active noise control laboratory2013Ingår i: Active Noise and Vibration Control in Practical System Implementations, 2013, artikel-id 731Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The remotely controlled laboratory setup for Active Noise Control (ANC) developed by Blekin-ge Institute of Technology, Sweden provides an efficient learning platform for the students to implement and learn ANC algorithms with real world physical system, hardware and signals. The initial laboratory prototype based on a Digital Signal Processor (DSP) TMS320C6713 from Texas Instruments (TI) was successfully tested with Filtered-x Least Mean Square (F-XLMS) algorithm applied to control noise in a ventilation duct. The resources of the DSP platform used in the remote laboratory setup enable testing and investigating substantially more challenging and computationally demanding algorithms. In this paper, we expand the horizon of the laboratory setup by testing more advanced and complicated single channel feed forward ANC algorithms. Filtered-x versions of algorithms such as the normalized least mean square (N-LMS), leaky least mean square (L-LMS), Filtered-U recursive least mean square (FURLMS) and recursive least square (RLS) algorithm etc. have been implemented utilizing the remote web based client provided in the remote laboratory. A comprehensive performance comparison of the aforementioned algorithms for the remote laboratory setup is presented to demonstrate the viability of the remote laboratory.

  • 58.
    Khan, Imran
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Muthusamy, Dinesh
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Ahmad, Wasim
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Nilsson, Kristian
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Zackrisson, Johan
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Gustavsson, Ingvar
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Remotely controlled laboratory setup for Active Noise Control and acoustic experiments2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a remotely controlled educational experiments setup for Active Noise Control (ANC) and acoustic experiments. The experiments setup is based on the Virtual Instruments Systems in Reality (VISIR) open source platform, National Instruments LabVIEW software and a Digital Signal Processor TMS320C6713 from Texas Instruments. The software development and equipment are controlled remotely form a client PC using a standard web browser. The proposed laboratory setup focuses on ANC experiments applied to noise in a ventilation duct. The laboratory setup will enable students to test and investigate properties and behaviour of adaptive algorithms in reality as compared to more confined simulations usually carried out in Matlab etc. The general steps in ANC, such as the feasibility of active control, designing, testing and debugging ANC algorithms, configuration and implementation of an active control system, are all covered. In addition students will be able to study the effect of analog to digital converters (ADC), anti-aliasing filters, digital to analog converters (DAC) and reconstruction filters using digital signal processing in reality, etc. The laboratory setup is suitable for a wide range of courses such as sound related experiments in upper secondary school physics, digital signal processing, adaptive signal processing, and acoustics at university level.

  • 59.
    khan, Imran
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Muthusamy, Dineshkumar
    Ahmad, Waqas
    Gustavsson, Ingvar
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Zackrisson, Johan
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Nilsson, Kristian
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Remotely Controlled Laboratory Setup for Active Noise Control and Acoustic Experiments2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a remotely controlled educational experiments setup for Active Noise Control (ANC) and acoustic experiments. The experiments setup is based on the Virtual Instruments Systems in Reality (VISIR) open source platform, National Instruments LabVIEW software and a Digital Signal Processor TMS320C6713 from Texas Instruments. The software development and equipment are controlled remotely form a client PC using a standard web browser. The proposed laboratory setup focuses on ANC experiments applied to noise in a ventilation duct. The laboratory setup will enable students to test and investigate properties and behaviour of adaptive algorithms in reality as compared to more confined simulations usually carried out in Matlab etc. The general steps in ANC, such as the feasibility of active control, designing, testing and debugging ANC algorithms, configuration and implementation of an active control system, are all covered. In addition students will be able to study the effect of analog to digital converters (ADC), anti-aliasing filters, digital to analog converters (DAC) and reconstruction filters using digital signal processing in reality, etc. The laboratory setup is suitable for a wide range of courses such as sound related experiments in upper secondary school physics, digital signal processing, adaptive signal processing, and acoustics at university level.

  • 60.
    khan, Imran
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Muthusamy, Dineshkumar
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Ahmad, Waqas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Gustavsson, Ingvar
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Zackrisson, Johan
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Nilsson, Kristian
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Johansson, Sven
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Remotely Controlled Active Noise Control Laboratories2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Remotely controlled laboratories in educational institutions are gaining popularity at an exponential rate due to the multidimensional benefits they provide. The Virtual Instrument Systems in Reality (VISIR) project by Blekinge Institute of Technology (BTH) Sweden has successfully implemented remotely controlled laboratories, with remotely controlled real instruments and experimental setups. Currently these laboratories provide students the opportunity to conduct experiments in the field of electronics, antenna theory and mechanical vibration measurements. In this paper a prototype system of a remotely controlled laboratory for active noise control (ANC) is introduced. The proposed lab will focus on addressing the problem of a ventilation duct noise. The laboratory is informative and to a great extent introduces a student to the general steps in ANC when it is suggested as a plausible solution for a noise problem. The student can perform an investigation concerning feasibility of active control, design, configuration and implementation of an active control system. The laboratory is based on a modern and relevant DSP platform with the corresponding software development environment controlled remotely. In addition, it may be utilized remotely both for lab assignments in acoustics courses and digital signal processing courses.

  • 61.
    Khan, Imran
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Nygren, Åse
    Blekinge Tekniska Högskola, Enheten för utbildningsutveckling.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    CHALLENGES IN FULFILLING THE INTENDED LEARNING OUTCOMES OF REMOTE LABORATORIES: A CASE STUDY OF ACTIVE NOISE CONTROL AND ACOUSTIC REMOTE LABORATORY.2015Ingår i: PROCEEDINGS OF THE 22ND INTERNATIONAL CONGRESS ON SOUND AND VIBRATION: MAJOR CHALLENGES IN ACOUSTICS, NOISE AND VIBRATION RESEARCH, 2015 / [ed] Crocker, MJ Pawelczyk, M Pedrielli, F Carletti, E Luzzi, S, INT INST ACOUSTICS & VIBRATION , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    The learning outcomes or educational objectives (goals) of a remote controlled laboratory via the Internet is the subject of discussion in this paper. The developers of remote laboratories are often self motivated individuals or academic groups, who only focus on development, accessibility and usability of their laboratories. The key question i.e. the intended learning outcomes or educational goals of a remotely controlled laboratory are frequently ignored or simply not given enough priority to be considered. This may lead to under utilization or complete failure of a particular remote laboratory. In this paper the challenges in formulating and achieving the educational objectives of a remotely controlled active noise control and acoustics laboratory are discussed.

  • 62.
    Khan, Imran
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Zmuda, M.
    Konopka, P.
    Gustavsson, Ingvar
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Enhancement of remotely controlled laboratory for Active Noise Control and acoustic experiments2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The latest important developments in the remotely controlled Active Noise Control (ANC) and Acoustics laboratory at Blekinge Institute of Technology (BTH), Sweden, are introduced. The remotely controlled laboratory is based on the Virtual Instruments Systems in Reality (VISIR) concept, and concerns multi-channel measurement and control of the sound field in a heating ventilation and air conditioning (HVAC) duct. Originally the ventilation duct was equipped with a fixed number of microphones at fixed spatial locations in the duct. A microphone positioning system has been designed and implemented. It enables control of the spatial positions of a number of microphones inside the HVAC duct using a suitable web interface for controlling stepper motors via a National Instruments (NI) PXI system. With the new developments, the spatial number of selectable positions for the microphones have been extended substantially. The new microphone positioning control system is presented and to enhance the user interaction with the laboratory equipment, an audio and visual system is also proposed.

  • 63.
    Källström, Elisabeth
    et al.
    Luleå Technical University/Volvo CE.
    Lindström, John
    Luleå Technical University.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Karlberg, Magnus
    Luleå Technical University.
    Lundin, J.
    Svensson, M.
    Larsson, J.
    ANALYSIS OF AUTOMATIC TRANSMISSION VIBRATION FOR CLUTCH SLIPPAGE DETECTION2015Ingår i: PROCEEDINGS OF THE 22ND INTERNATIONAL CONGRESS ON SOUND AND VIBRATION: MAJOR CHALLENGES IN ACOUSTICS, NOISE AND VIBRATION RESEARCH, 2015 / [ed] Crocker, MJ; Pawelczyk, M; Pedrielli, F; Carletti, E; Luzzi, S, INT INST ACOUSTICS & VIBRATION, AUBURN UNIV , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Heavy duty construction equipment is generally equipped with automatic transmission enabling to change gear ratio automatically. The clutches in an automatic transmission transfer torque from the engine to the gearbox and clutch failures may result in costly downtime of construction equipment. To prevent costly downtime of construction equipment, condition monitoring in combination with condition based maintenance may be utilized. Different sensor data are collected on a machine that enables condition monitoring. Vibration have been measured on an automatic transmission in a construction equipment machine during controlled driving sessions, with and without clutch slippage, on a test track. An initial investigation of the vibration measured on the automatic transmission have been carried out with the purpose to find out if the vibration may contain reliable information related to clutch slippage considered to be abnormal. Initial signal analysis of the data have been carried out using Spectrogram and Spectral Kurtosis methods. The results indicate that information related to abnormal clutch slippage may be extracted from vibration measured on an automatic transmission in a construction equipment machine.

  • 64.
    Källström, Elisabeth
    et al.
    Volvo, SWE.
    Lindström, John
    Luleå tekniska Universitet, SWE.
    Lars, Håkansson
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Karlberg, Magnus
    Luleå tekniska Universitet, SWE.
    Öberg, Olof
    Volvo, SWE.
    Renderstedt, Reza
    Volvo, SWE.
    Larsson, Jonas
    Volvo, SWE.
    Identification of vibration properties of heavy duty machine driveline parts as a base for adequate condition monitoring: Torque converter2016Ingår i: ICSV 2016 - 23rd International Congress on Sound and Vibration: From Ancient to Modern Acoustics / [ed] Vogiatzis, K; Kouroussis, G; Crocker, M; Pawelczyk, M, INT INST ACOUSTICS & VIBRATION , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Improving uptime is paramount in the heavy duty construction equipment business. Failure of critical components in the heavy duty machine may lead to unnecessary stops and expensive downtime. The torque converter, a complex component of the driveline, transmits and multiplies torque from the engine to the gearbox, and its failure may not only lead to the machine standing still but may also lead to damage of other parts of the automatic transmission. For adequate condition monitoring of the torque converter, different sensor data are measured on a construction equipment machine during controlled driving sessions. Vibration has been measured on the torque converter. An initial investigation of the vibration measured on the torque converter has been carried out to identify its vibration properties in order to enable its health monitoring to prevent failure. Initial signal analysis of the data have been carried out using Order Power Spectrum and Order Modulation Spectrum methods. The results indicate that the torque converter vibration properties contain information relevant for early fault detection.

  • 65.
    Källström, Elisabeth
    et al.
    Lulea tekniska Universitet, SWE.
    Olsson, Tomas
    RISE SICS, SWE.
    Lindström, John
    Lulea tekniska Universitet, SWE.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Larsson, Jonas
    Volvo, SWE.
    On-board clutch slippage detection and diagnosis in heavy duty machine2018Ingår i: International Journal of Prognostics and Health Management, ISSN 2153-2648, E-ISSN 2153-2648, Vol. 9, nr 1, artikel-id 007Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to reduce unnecessary stops and expensive downtime originating from clutch failure of construction equipment machines; adequate real time sensor data measured on the machine in combination with feature extraction and classification methods may be utilized. This paper presents a framework with feature extraction methods and an anomaly detection module combined with Case-Based Reasoning (CBR) for on-board clutch slippage detection and diagnosis in heavy duty equipment. The feature extraction methods used are Moving Average Square Value Filtering (MASVF) and a measure of the fourth order statistical properties of the signals implemented as continuous queries over data streams. The anomaly detection module has two components, the Gaussian Mixture Model (GMM) and the Logistics Regression classifier. CBR is a learning approach that classifies faults by creating a new solution for a new fault case from the solution of the previous fault cases. Through use of a data stream management system and continuous queries (CQs), the anomaly detection module continuously waits for a clutch slippage event detected by the feature extraction methods, the query returns a set of features, which activates the anomaly detection module. The first component of the anomaly detection module trains a GMM to extracted features while the second component uses a Logistic Regression classifier for classifying normal and anomalous data. When an anomaly is detected, the Case-Based diagnosis module is activated for fault severity estimation. © 2018, Prognostics and Health Management Society. All rights reserved.

  • 66. Lagö, Thomas L
    et al.
    Claesson, Ingvar
    Håkansson, Lars
    Overview on Adaptronics and the Future with Smart Embedded Systems2007Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Noise and vibration exposure for humans has been of interest for many years. Empirical data has verified that too high dose values can create multiple problems to a human body - often severe. Therefore, spot dose measurements have been used to verify that exposure levels are within acceptable limits. In 2006, the European Machinery Directive increased the responsibility for manufacturers and employers to make sure that limits are in compliance with legislation. The type of classical technology currently used, often employs passive solutions aimed at trying to reduce noise and vibration levels. For low frequency applications, these methods are often inadequate and lack the required level of performance. A smart combination of passive and active techniques can provide many improvements. Today, with possibilities for low cost and embedded electronics, and the rapid development of new actuators, a vast range of applications are possible for this combined approach. A financial advantage also exists when combining active and passive control methods. Today, multiple products utilize embedded "electronic muscles" that counteract harmful sound and vibrations in real-time - featuring advanced control systems. All this then becomes an invisible function in the vehicle, machine, or tool. The launch of such systems and successful acceptance requires international compliance with applicable standards. Via extensive international networks and scientific leadership in multiple organizations, we have managed to develop a range of new products meeting the requirements of international standards. One project, I-SPIDER, is aimed at addressing environmental parameters in schools: an area where our new smart and embedded technology plays a key role. Acticut®, the company that won the Large Embedded Award in Sweden (2006) is another example of how a smart and embedded system can accomplish a task that many people believe to be impossible. New sensor concepts and approaches in combination with consumer and automotive wireless and network solutions are key ingredients for success. It is impossible to imagine how the smart and embedded technology will revolutionize the sound and vibration business and open completely new business segments. This paper will outline these new markets and applications.

  • 67. Lagö, Thomas L
    et al.
    Håkansson, Lars
    Åkesson, Henrik
    Classification of metal cutting vibrations, is it all chatter?2008Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Chatter vibrations are causing large monetary losses daily in industry. New materials have increased the challenges with harmful vibration levels. Since the vibrations, when observed as a final result, are chaotic and the vibration process nonlinear, it is a challenging task to deal with it. It is also a common “understanding” in the cutting industry that chatter is RPM (the rotational speed) dependent, since the behaviour changes with RPM. Many attempts have been done over many years to mitigate and understand the vibrations. In our vast research on these topics, we have found that it is rewarding to classify the vibrations into categories, enabling a better understanding of its underlaying physics and “source of vibrations,” and thus also the formulation of a possible remedy. An analysis approach has been developed where vibrations are analyzed and categorized and a GO/NOGO indicator is telling if the machine has the “right type of vibrations.” The work includes a unique solution to inhibit the chatter process and allowing metal cutting without harmful vibrations, the Acticut™ Smart Cutting product line. This article will discuss how such machine testing can be performed and what solutions are at hand, thus saving important money for the companies and also increases quality.

  • 68. Lagö, Thomas L
    et al.
    Olsson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    Design of an Efficient Chatter Control System For Turning and Boring2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the turning operation chatter or vibration is a frequent problem, which affects the result of the machining, and, in particular, the surface finish. Tool life is also influenced by vibration. Severe acoustic noise in the working environment frequently occurs as a result of dynamic motion between the cutting tool and the workpiece. In all cutting operations like turning, boring and milling vibrations are induced due to the deformation of the workpiece. This implies several disadvantages, economical as well as environmental. Many different solutions to minimize the problem have been developed but the fundamental problem is still there. The true nature of the vibrations, its causes, and implications were revealed in a doctor’s thesis in 1999. This has led to a break through in this research area. Since then, through recent research results at Blekinge Institute of Technology, a new approach to controlling vibrations in cutting operations in a lathe has been implemented in a product called ActicutTM, developed by Active Control Sweden AB. This new method controls vibrations in the cutting direction.

  • 69. Lagö, Thomas L
    et al.
    Olsson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    Performance of a Chatter Control System for Turning and Boring Applications2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the turning operation chatter or vibration is a frequent problem, which affects the result of the machining, and, in particular, the surface finish. Tool life is also influenced by vibration. Severe acoustic noise in the working environment frequently occurs as a result of dynamic motion between the cutting tool and the workpiece. In all cutting operations like turning, boring and milling vibrations are induced due to the deformation of the workpiece. This implies several disadvantages, economical as well as environmental. Many different solutions to minimize the problem have been developed but the fundamental problem is still there. The true nature of the vibrations, its causes, and implications were revealed in a doctor’s thesis in 1999, [1]. This has led to a break through in this research area. Since then, through recent research results at Blekinge Institute of Technology, a new approach to controlling vibrations in cutting operations in a lathe has been implemented in a product called Acticut®, developed by Active Control Sweden AB. This new method controls vibrations in the cutting direction using embedded sensors and actuators and a filtered-x LMS algorithm. This paper will discuss the application but also the algorithm and its main numerical properties to accomplish a good result, still maintaining its stability properties.

  • 70. Lagö, Thomas L
    et al.
    Zimmergren, Rolf
    Boyer, Alan
    Claesson, Ingvar
    Håkansson, Lars
    New cutting technology provides improved workpiece finish and increased tool life2006Ingår i: SOUND AND VIBRATION, ISSN 0022-460X , s. 7-8Artikel i tidskrift (Refereegranskat)
  • 71. Larsson, Martin
    et al.
    Johansson, Sven
    Claesson, Ingvar
    Håkansson, Lars
    A Module Based Active Noise Control System for Ventilation Systems, Part I: Influence of Measurement Noise on the Performance and Convergence of the Filtered-x LMS Algorithm2009Ingår i: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 14, nr 4, s. 188-195Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Low noise level is an essential feature when installing ventilation systems today. To achieve attenuation over a broad frequency range, the passive silencers traditionally used to attenuate ventilation noise can be combined with an active noise control (ANC) system. To insure reliable operation and desirable levels of attenuation when applying ANC to duct noise, it is highly important to be able to suppress the contamination of the microphone signals due to the turbulent pressure fluctuations arising as the microphones are exposed to the airflow in the duct. This paper is the first in a series of two, that treats the problem of turbulence induced noise originating from the airflow inside the ducts. Part I is concerned with theoretical and experimental investigations of the influence of the turbulence induced noise on the adaptive algorithm in the ANC system. Part II is concerned with design and investigations of microphone installations for turbulence suppression and results concerning the performance of an ANC system with the different microphone installations are presented. Some of the results were obtained at an acoustic laboratory according to an ISO-standard. The attenuation achieved with ANC was approximately 15-25 dB between 50-315 Hz even for airflow speeds up to 20 m/s.

  • 72. Larsson, Martin
    et al.
    Johansson, Sven
    Claesson, Ingvar
    Håkansson, Lars
    A Module Based Active Noise Control System for Ventilation Systems, Part II: Performance Evaluation2009Ingår i: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 14, nr 4, s. 196-206Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To utilize the full noise attenuation potential of an active noise control (ANC) system applied to duct noise, it is important to be able to minimize the turbulence induced noise in the microphone signals. This is the second paper in a series of two, that treats the problem of turbulence induced noise originating from the airflow inside the ducts, when applying ANC to ducts. Part I contains theoretical and experimental investigations of the influence of the turbulence induced noise on the filtered-x LMS algorithm used in the ANC system. Part II (the present paper) is concerned with design and investigations of microphone installations which produces a sufficient amount of turbulence suppression while also meeting industry requirements. These requirements are, for example, that the microphone installations should be based on standard ventilation parts, and that they should be easily installed and maintained. Furthermore, results concerning the performance of an ANC system with different microphone installations are presented. Some of the results were obtained at an acoustic laboratory according to an ISO standard. The attenuation achieved with ANC was approximately 15-25 dB between 50-315 Hz even for airflow speeds up to 20 m/s.

  • 73. Larsson, Martin
    et al.
    Johansson, Sven
    Claesson, Ingvar
    Håkansson, Lars
    Influence of measurement noise on the performance and convergence of the filtered-x LMS algorithm; Theory and simulations2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In active noise control (ANC) applications the sensor signals feeding the controller may be contaminated by signal components not linearly related to the actual noise to be controlled, e.g. measurement noise. An example is the noise in the microphone signals generated by airflow turbulence when applying ANC to ducts. The measurement noise may significantly degrade the performance of an ANC system. This paper is concerned with theoretical investigations of the influence of measurement noise on the performance and convergence of the filtered-x LMS algorithm. Further, computer simulations have been performed to verify the theoretical results. In the theoretical investigations, the convergence of the filtered-x LMS algorithm is derived for different cases with measurement noise affecting the different sensor signals. These cases are compared to the ideal case with no measurement noise present at neither sensor signal. The results from both the theoretical investigations and the simulations show that measurement noise can, depending on the SNR of the sensor signals, degrade the performance of the filtered-x LMS algorithm regarding both the filter coefficients the algorithm converges to in mean, and the convergence rate of the algorithm.

  • 74. Larsson, Martin
    et al.
    Johansson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    A FEEDFORWARD ACTIVE NOISE CONTROL SYSTEM FOR DUCTS USING A PASSIVE SILENCER TO REDUCE ACOUSTIC FEEDBACK2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ventilation systems installed in buildings usually generate low-frequency noise because the passive silencers commonly used to attenuate the ventilation noise are not effective in the low-frequency range. A method proven to effectively reduce low-frequency noise in a wide variety of applications is active noise control (ANC). A feedforward ANC system applied to duct noise normally uses a reference microphone, a control unit, a loudspeaker to generate the secondary noise created by the controller, and an error microphone. The secondary noise generated by the loudspeaker will travel both downstream canceling the primary noise, and upstream to the reference microphone, i.e. acoustic feedback. The acoustic feedback may result in performance reduction and stability problems of the control system. Common approaches to solve the feedback problem result in more complex controller structures and/or system configurations than the simple feedforward controller, e.g. introducing a feedback cancellation filter in the controller in parallel with the acoustic feedback path, or using a dual-microphone reference sensing system. This paper presents a simple approach to reduce the acoustic feedback by using a basic feedforward controller in combination with a passive silencer. Simulations show that efficient acoustic feedback cancellation is achieved by using a passive silencer. In the experimental setup another advantage with using a passive silencer is that the frequency response function of the forward path, which is to be estimated, is smoother, i.e. most of the dominant frequency peaks in the frequency response function when not using a passive silencer is reduced. This in turn results in an acoustic path that is less complex to estimate with high accuracy using an adaptive FIR filter steered with the LMS algorithm.

  • 75. Larsson, Martin
    et al.
    Johansson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    A SYSTEM IMPLEMENTATION OF AN ACTIVE NOISE CONTROL SYSTEM COMBINED WITH PASSIVE SILENCERS FOR IMPROVED NOISE REDUCTION IN DUCTS2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a feedforward active noise control system combined with passive silencers for reducing acoustic noise propagating through ventilation ducts. It is investigated if the passive silencers can increase the noise attenuation potential of the active noise control system and experimental results are presented. The results show that installing a passive silencer results in less pronounced standing waves in the duct and hence to performance increase of the active noise control system. Evaluating measurements regarding the performance of the active noise control system have also been conducted in an acoustic laboratory according to an ISO-standard.

  • 76. Larsson, Martin
    et al.
    Johansson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    Experimental Investigations of Different Microphone Installations for Active Noise Control in Ducts2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    A request on ventilation systems today is the feature of a low noise level. A common method to attenuate ventilation noise is to use passive silencers. However, such silencers are not suitable for the lowest frequencies and one solution is to use active noise control (ANC) to increase the noise attenuation in the low frequency range. Normally when using a feedforward ANC system to attenuate duct noise, both the reference microphone and the error microphone are exposed to airflow. As the airflow excites the diaphragm of the microphones, the microphone signals become contaminated by uncorrelated pressure fluctuations that are not part of the sound propagating in the duct. By reducing the flow velocity around the microphones, these uncorrelated pressure fluctuations can be reduced and the noise reduction improved. One way to reduce the flow velocity around the microphones is to place the microphones in outer microphone boxes connected to the duct via a small slit. In this paper a new practical design for the reduction of flow velocity around the microphones is presented; the microphone installation is based on a T-duct, and therefore it makes maintenance and especially construction easier, compared to the microphone box with a slit. Furthermore, comparative results concerning the performance of an ANC system for the two different microphone installations, the T-duct configurations and the microphone boxes with varying slit width, are presented. The results show that the active noise control performance is almost equal when using the suggested microphone installation as compared to when using a microphone box with a slit.

  • 77. Larsson, Martin
    et al.
    Johansson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    Microphone Windscreens for Turbulent Noise Suppression when Applying Active Noise Control to Ducts2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Low noise level is an essential feature when installing ventilation systems nowadays. The traditional noise control approaches use passive silencers to attenuate the undesired ventilation noise. These silencers have a high attenuation over a broad frequency range. However, traditional passive silencers are ineffective at low frequencies and tend to be relatively large and bulky when they are used for low frequencies. An approach to improve the low frequency noise attenuation and to reduce the size of a low frequency silencer is active noise control (ANC). A problem when applying ANC to attenuate noise in ducts is that both the reference microphone and the error microphone are placed in an air flow. Accordingly, the microphones sense the sound propagating through the duct as well as the turbulent fluctuations generated by the wind passing over the microphones. The turbulent flow noise reduces the coherence between the reference microphone and the error microphone, resulting in reduced performance of a feedforward ANC system. For improving the performance it is important with as little corruption from turbulent flow noise as possible. The coherence can be improved by reducing the flow velocity around the microphones by using some kind of windscreen. This paper presents comparison results for microphone installations based on different windscreens for suppression of the turbulent wind noise. The presented measurements are carried out in the frequency range 0-400 Hz - the plane wave propagation region for the ducts in use - and for flow speeds up to 5,9 m/s. The results show that with appropriate screens and placement the attenuation and frequency range of attenuation can be significantly improved.

  • 78. Larsson, Martin
    et al.
    Johansson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    Performance Evaluation of a Module Configured Active Silencer for Robust Active Noise Control of Low Frequency Noise in Ducts2008Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Low noise level is an essential feature when installing ventilation systems today. Since the passive silencers traditionally used to attenuate ventilation noise tend to become bulky, impractical, and expensive when designed for low frequency attenuation, other solutions for the reduction of the low frequency duct noise often present in ducts are of interest. Active noise control (ANC) is a well known method for attenuating low frequency noise and much research has been performed to successfully apply ANC to duct noise. To insure reliable operation and desirable levels of attenuation when applying ANC to duct noise, it is of highest importance to be able to suppress the contamination of the microphone signals due to the turbulent pressure fluctuations arising as the microphones are exposed to the airflow in the duct. The work presented in this report is concerned with analysis of the influence of the turbulence induced noise on the adaptive algorithm in the ANC system, and design of microphone installations which produce sufficient turbulence suppression while also meeting industrial requirements. These requirements are, for example, that the installations should be based on standard ventilation parts, and that they should be easily installed and maintained. Furthermore, results concerning the performance of an ANC system with different microphone installations are presented. Some of the results were obtained at an acoustic laboratory according to an ISO standard. The attenuation of duct noise achieved with ANC was approximately 15-25 dB between 50-315 Hz, even for airflow speeds up to 20 m/s.

  • 79. Larsson, Martin
    et al.
    Johansson, Sven
    Muddala, S.M.
    Gafar, A.E. Mohamed
    Håkansson, Lars
    Tarkka, Juhani
    Sandor, Mats
    An Initial Study on Applying Active Noise Control to an Insulated Box Fan Used in Ventilation System Applications2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    In many different applications and buildings fans are used to remove unwanted and used air. These fans often generate broadband and tonal noise. Commonly, passive resistive silencers are used to attenuate noise generated by different types of fans installed in ventilation systems. Passive silencers tend to become bulky and impractical when designed for low frequency attenuation. However, active noise control (ANC) is a technique known for its ability to produce high levels of attenuation in the low frequency range, even with a relatively moderate sized ANC system. This paper presents an initial study performed to investigate the possibilities of applying ANC to a radial fan installed inside a box, an insulated box fan. The box is connected to a duct system and can for example be used as a waste air fan. The primary interest in this application, when the fan is used as a waste air fan, is to attenuate the noise generated on the suction side, since that side generates noise into a particular room. Investigations were carried out to determine where the ANC system should be installed, e.g. inside the box, in the duct connected to the box etc. Factors considered were for example, turbulence, standing waves, the type of noise generated by the fan (tonal, broadband, or a combination), and space limitations. The noise generated by the fan was found to be dominated by a tonal component, but also to have broadband energy in the low frequency range. Further, a feedforward ANC system was applied on the suction side, producing approximately 28 dB attenuation of the tonal component, and 5-10 dB attenuation of the broadband noise between 50 and 200 Hz.

  • 80. Larsson, Martin
    et al.
    Nilsson, Kristian
    Johansson, Sven
    Claesson, Ingvar
    Håkansson, Lars
    An Active Noise Control Approach for Attenuating Noise Above the Plane Wave Region in Ducts2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In a narrow duct, a relatively simple single-channel feedforward ANC system may be used to attenuate noise propagating as plane waves. However, for ducts with larger dimensions the cut-on frequencies for one or several higher-order acoustic modes may be within the frequency range where ANC is applied. In such situations it is generally necessary to use a multiplechannel feedforward ANC system with several secondary sources, error sensors, and perhaps reference sensors. Such a system has a significantly higher complexity than a single-channel ANC system. In this paper another approach is described. Instead of using a multiple-channel feedforward ANC system on a duct of large dimension, the idea is to divide the duct into several more narrow parallel ducts. In this way the complexity of the ANC system may be reduced. In the experiments conducted for this paper, a duct was divided into two more narrow ducts. The noise propagating in each duct was controlled by a feedforward ANC system based on the leaky filtered-x LMS algorithm, where different reference- and error microphone configurations were used. The different configurations were compared to a configuration where the noise in respective narrow duct was controlled using a basic single-channel ANC system per duct. The results preliminary show that high attenuation of low-frequency noise in a duct of large dimension may be achieved using this approach.

  • 81.
    Magnus, Berggren
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Nilsson, Kristian
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Agnesson, Helen
    Hedsten, Stefan
    Noise measurements in incubators at neonatal intensive care unit2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The purpose of this study was to investigate the noise properties and levels of common noise sources in a neonatal intensive care unit (NICU) and in particular inside and around an incubator. Many previous studies have been made on noise levels in NICU, frequently focusing on A-weighted sound levels. In this study it was not assumed that infant's hearing follows the same equal loudness curve as adults and hence instead of A-weighting, short time averaged sound spectra in the frequency range 20 Hz to 20 kHz was logged to identify the frequency distribution of specific noise generating events. It was seen that alarms and CPAP air-flow increased the noise level by up to 8 dB outside but was barely noticed inside when considering the un-weighted noise level. However, by analyzing individual frequencies, most events were noticeable inside the incubator. For instance, frequencies above 1 kHz were increased by 10 dB inside and 11 dB outside the incubator when CPAP was turned on. Opening and closing the incubator increased the un-weighted noise level by 8 dB inside and 7 dB outside.

  • 82. Mohammadnejad, M.
    et al.
    Ghazvini, .
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    INITE ELEMENT MODELING OF DYNAMICPROPERTIES OF POWER SUPPLY FOR AN INDUSTRIAL APPLICATION2015Konferensbidrag (Övrigt vetenskapligt)
  • 83.
    Mohammadnejad, Mostafa
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Ghazvini, Mandi
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling. Blekinge Inst Technol, Via Valhallavagen, S-37141 Karlskrona, Sweden..
    FINITE ELEMENT MODELING OF DYNAMIC PROPERTIES OF POWER SUPPLY FOR AN INDUSTRIAL APPLICATION2015Ingår i: PROCEEDINGS OF THE 22ND INTERNATIONAL CONGRESS ON SOUND AND VIBRATION: MAJOR CHALLENGES IN ACOUSTICS, NOISE AND VIBRATION RESEARCH, 2015 / [ed] Crocker, MJ Pawelczyk, M Pedrielli, F Carletti, E Luzzi, S, INT INST ACOUSTICS & VIBRATION , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study, the dynamic properties of the mechanic structure of Power Supply for an industrial application is considered. A finite element model of the Power Supply mechanic structure has been generated with the aid of the MSC Marc software. Based on the FE model; modal analysis has been carried out and the eigenfrequencies and eigenmodes for the FE model have been calculated in a suitable frequency range. Relevant frequency response functions for the FE model have been produced using dynamic harmonic analysis. To validate and update the FE model, experimental modal analysis has been carried out on a Power Supply. For the experimental modal analysis the MIMO method the polyreference least-squares complex exponential method has been used. Based on the updated FE model some modified Power Supply designs are suggested with improved dynamic properties in an adequate frequency range.

  • 84. Nilsson, Mikael
    et al.
    Nordberg, Jörgen
    Håkansson, Lars
    Claesson, Ingvar
    Feature Extraction and Classification Approaches in Condition Based Monitoring2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Creating a supervision tool in Condition Based Monitoring (CBM) for manufacturing processes by means of a pattern recognition approach, with emphasis on the feature extraction and classification is usually a difficult task. In particular manufacturing methods like drilling, turning, milling, boring and grinding are of concern for the discussion. The issue of machine tool downtime and degraded productivity and production costs continues to plague the industry and thus urge for reliable CBM systems enabling to predict or detect vibration, estimating tool wear and detect tool breakage. Extracting relevant information and choosing a suitable classifier is far from trivial for a given CBM scenario and requires knowledge of the process involved. This paper will discuss some common techniques used and also aim to indicate possible new approaches utilizing emerging techniques from other disciplines. In particular, nonlinear techniques such as Local Binary Pattern (LBP) and variants thereof are investigated as possible techniques for feature extraction. Generative as well as discriminative classifiers are also discussed.

  • 85. Olsson, T.
    et al.
    Källström, Elisabeth
    Gillblad, D.
    Funk, P.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Lundin, J.
    Svensson, M.
    Larsson, J.
    Fault Diagnosis of Heavy Duty Machines: Automatic Transmission Clutches2014Ingår i: Proceedings of the Workshop Program of ICCBR-14, 2014Konferensbidrag (Refereegranskat)
  • 86. Persson, Per
    et al.
    Johansson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    Lateral Vibration Reduction in a Train Car Using Active Control Technologies2001Konferensbidrag (Refereegranskat)
    Abstract [en]

    The problem of low-frequency lateral train-car vibration is an important issue surrounding the design of high-speed trains. Passive solutions such as stiffening the car chassis are impractical because of the weight increase. Semi-passive solutions, such as modifying the structural dynamics of the carbody through non-rigid coupling of heavy underfloor equipment does not incur a weight penalty, but does not sufficiently reduce the vibrations. However, computer simulations based on signals derived from a dynamic computer model of a train car indicates that the incorporation of an active control system, in addition to the semi-passive approach, is likely to give a substantial reduction in the lateral vibration level. The paper addresses some design aspects and different controller structures for the active control system. The adaptive controller is based either on feedforward or feedback control strategy. Results from computer simulations indicate that a feedback system would function as well as a multiple-reference feedforward system. However, by using a robust feedback-LMS controller the complexity of the control system may be reduced substantially. The control results illustrate an attenuation of the lateral train-car vibration by up to 15 dB.

  • 87. Persson, Per
    et al.
    Johansson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    Samuels, Timothy
    Feedback-LMS control of lateral vibration in a train car2001Konferensbidrag (Refereegranskat)
    Abstract [en]

    The problem of low-frequency lateral train-car vibration is an important issue surrounding the design of high-speed trains. Passive solutions such as stiffening the car chassis are impractical because of the weight increase. Semi-passive solutions, such as modifying the structural dynamics of the carbody through non-rigid coupling of heavy underfloor equipment does not incur a weight penalty, but does not sufficiently reduce the vibrations. However, computer simulations based on signals derived from a dynamic computer model of a train car indicates that the incorporation of a multiple-reference feedforward active control system, in addition to the semi-passive approach, is likely to effect a substantial reduction in the lateral vibration level. The complexity of the control system may be reduced by using a robust feedback-LMS controller. Results from computer simulations indicate that a feedback system would function as well as, and potentially better than, a feedforward system. The control results illustrate attenuation of the lateral train-car vibration of up to 15 dB.

  • 88. Pettersson, Linus
    et al.
    Håkansson, Lars
    Claesson, Ingvar
    Olsson, Sven
    Active Control of Boring Bar Vibrations in Cutting Operations2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internal turning or boring operations have a history of being a cumbersome manufacturing process. The manufacturing industries are facing tougher tolerances of their product surfaces and a desire to process hard to cut materials and therefore the vibrations must be kept to a minimum. An increase in the productivity is also interesting from a production point of view. When cutting in pre-drilled holes the boring bar is usually long and slender and is thereby inclined to vibrate destructively concerning the machining result. The knowledge of the vibrations involved in boring operations and active control of external turning operations, have given a good basis for the active control solution in boring operations. The active control solution is based on a standard boring bar with an embedded piezo ceramic actuator placed at the peak modal strain of the boring bar. An accelerometer is also included in the design, mounted as close as possible to the cutting tool. The control algorithm is a filtered X LMS algorithm built on a feedback approach since the original excitation, the cutting process, cannot be observed directly. Preliminary results show reduction of the vibration in the boring bar by up to 30dB.

  • 89. Pettersson, Linus
    et al.
    Håkansson, Lars
    Claesson, Ingvar
    Olsson, Sven
    Active Control of Internal Turning Operations Using a Boring Bar2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    Vibrations in internal turning or boring operations are usually a cumbersome part of the manufacturing process. The manufacturing industries are having problems with these kinds of cutting operations. When cutting in pre-drilled holes the cross sectional area of the boring bar is limited at the same time as it is long. Since a general boring bar is long and slender it is sensitive to external excitation and thereby inclined to vibrate. The vibration problem affects the surface finish in particular. The demand for smaller and smaller tolerances of the surface finish leads to that the manufacturing industry seeks for a solution to the boring bar vibration problem. The tool life is also likely to be influenced by the vibrations involved in a cutting operation. Another problem in boring operations is the high noise level in the cutting process. The noise level in the environment of the operators is today more and more regulated, especially in the western world. Active vibration control will reduce the amount of vibrations in the cutting operations. Since the noise is induced by the vibration of the boring bar, the noise level will also be reduced due to the cancellation of the noise source. Preliminary results show reduction of vibrations in the boring bar by up to 30dB.

  • 90. Pettersson, Linus
    et al.
    Håkansson, Lars
    Claesson, Ingvar
    Olsson, Sven
    Active Control of Machine-Tool Vibration in a CNC Lathe Based on an Active Tool Holder Shank with Embedded Piezo Ceramic Actuators2001Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the turning operation chatter or vibration is a frequent problem affecting the result of the machining, and, in particular, the surface finish. Tool life is also influenced by vibration. Severe acoustic noise in the working environment frequently occurs as a result of dynamic motion between the cutting tool and the workpiece. These problems can be reduced by active control of machine-tool vibration. However, machine-tool vibration control systems are usually not applicable to a general lathe and turning operation. The physical features and properties of the mechanical constructions or solutions involved regarding the introduction of secondary vibration usually limit their applicability. An active control solution for a general lathe application has been developed. It is based on a standard Industry tool holder with an embedded piezo ceramic actuator and an adaptive feedback controller. The adaptive controller is based on the well known filtered-x LMS-algorithm. It enables substantial reduction of the vibration level by up to 40 dB at 3.4 kHz.

  • 91. Pettersson, Linus
    et al.
    Håkansson, Lars
    Claesson, Ingvar
    Olsson, Sven
    Active Control of Machine-Tool Vibration in Cutting Operations in a General Lathe2001Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the general lathe the turning operation chatter or vibration is a frequent problem affecting the result of the machining, and, in particular, the surface finish. Tool life is also influenced by vibration. Severe acoustic noise in the working environment frequently occurs as a result of dynamic motion between the cutting tool and the workpiece. These problems can be reduced by active control of machine-tool vibration. In a general lathe the physical features and properties of an ctive control system usually limit their applicability. By using piezo ceramic actuators some constraints regarding the mechanical construction of the active tool holder can be circumvented. An active control solution for a general lathe application has been developed. It is based on a standard industry tool holder with an embedded piezo ceramic actuator and an adaptive feedback controller. The adaptive controller is based on the well known filtered-x LMS-algorithm. It enables substantial reduction of the vibration level by up to 40 dB at 3.4 kHz.

  • 92. Pettersson, Linus
    et al.
    Håkansson, Lars
    Claesson, Ingvar
    Olsson, Sven
    Active Control of Machine-Tool Vibration in Cutting Operations using Piezo Ceramic Actuators2001Konferensbidrag (Refereegranskat)
  • 93. Pettersson, Linus
    et al.
    Håkansson, Lars
    Claesson, Ingvar
    Olsson, Sven
    Adaptive Control of Machine-Tool Vibration Based on an Active Tool Holder Shank with an Embedded Piezo Ceramic Actuator2001Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the turning operation chatter or vibration is a common problem affecting the result of the machining, and, in particular, the surface finish. Tool life is also influenced by vibration. Severe acoustic noise in the working environment frequently occurs as a result of dynamic motion between the cutting tool and the workpiece. These problems can be reduced by active control of machine-tool vibration. However, machine-tool vibration control systems are usually not applicable to a general lathe and turning operation. The physical features and properties of the mechanical constructions or solutions involved regarding the introduction of secondary vibration usually limt their applicability. An adaptive active control solution for a general lathe application has been developed. It is based on a standard industry tool holder shank with an embedded piezo ceramic actuator and an adaptive feedback controller. The adaptive controller is based on the well known filtered-x LMS-algorithm. It enables substantial reduction of the vibration level by up to 40 dB at 3.4 kHz.

  • 94.
    Premachandran, Rammohan
    et al.
    Atlas Copco.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    SIGNAL ANALYSIS FOR PERFORMANCE MONITORINGOF DRILLING WITH DOWN THE HOLE (DTH) ROCK DRILLS2015Ingår i: PROCEEDINGS OF THE 22ND INTERNATIONAL CONGRESS ON SOUND AND VIBRATION: MAJOR CHALLENGES IN ACOUSTICS, NOISE AND VIBRATION RESEARCH, 2015, INT INST ACOUSTICS & VIBRATION , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today rock drilling operations mainly relies on the experience of the operators. Expe-rienced drillers observes the sound produced by the drilling machinery and in general, base their judgments on their intuition. An efficient drill monitoring system, providing reliable and robust in-formation on the performance of the drilling process, is likely to provide experienced drillers with additional information, to further improve the drilling process. Such a system is also likely to provide guidance to inexperienced drillers to improve their drilling performance concerning quality and efficiency. To enable monitoring of drilling performance in down the hole (DTH) rock drilling, simultaneous measurements of vibrations, with the aid of accelerometers mounted at specific locations on the drill rig, and other quantities such as different line pressures controlling different movements of the drill string are considered in combination with suit-able signal processing methods. A number of properties, e.g. spectral properties, of the vibration sig-nals and the pressure line signals under good drilling and bad drilling conditions are compared. Both the vibration and pressure signals display distinguishable properties between the case of "good" drill-ing and the case of "bad" drilling.

  • 95.
    Premachandran, Rammohan Kodakadath
    et al.
    Atlas Copco, SWE.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Comparison of spectral properties of the vibration signals and line pressure signals of DTH drills2016Ingår i: ICSV 2016 - 23rd International Congress on Sound and Vibration: From Ancient to Modern Acoustics, International Institute of Acoustics and Vibrations , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Quantifying and Monitoring of drilling performance are becoming exceedingly important in the case of Down the Hole drilling. Various economic, environmental and safety constraints are driving the drilling process to become more efficient. To make a robust system that would enable the performance/condition monitoring of the drilling, we must understand how different properties like different line pressure etc. respond to various drilling conditions and what information can they provide regarding the Drilling Performance. A comparison of different properties like spectral properties, of the vibration signals and Pressure signals under known conditions would enable better understanding of the drilling system and the physics behind the process. A comparison is made between the Spectral properties of the vibrational signals obtained from remote locations on the drill rig and pressure signals that provide the feed and holdback forces to the drill string and a correlation between their characteristics and patterns under good and bad drilling conditions have been made. A simplified model of the system is simulated and results are compared with the patterns obtained from analyzing the Vibration signals.

  • 96. Samuels, Timothy
    et al.
    Persson, Per
    Johansson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    Active control of lateral vibration in a structurally modified train car2000Konferensbidrag (Refereegranskat)
    Abstract [en]

    As trains are continually designed for higher speeds the problem of railcar vibration grows worse. Lateral vibrations in a train car are noticeable to passengers if the frequency contents are lower than approximately 20 Hz, and complaints of nausea are not uncommon. The passive solution of stiffening the car chassis to shift the vibrational frequencies higher results in inflated manufacturing and running costs, and opposes higher travel speeds due to increased weight. Semi-passive solutions, such as modifying the structural dynamics of the carbody by decoupling heavy underfloor equipment, do not sufficiently reduce the vibrations. However, by appending a multi-reference feedforward active vibration controller, a substantial reduction in the lateral vibration level is to be expected. Based on a dynamic computer model of a train car simulating the lateral vibration, which uses as input bogie acceleration data measured on a running train, multiple-input/single-output coherence spectra were estimated to determine a suitable set of reference signals to an active control system. A dual-reference controller implies a theoretical maximum attenuation of 28 dB at the objective frequency of 10 Hz. Control simulations are carried out using different reference signal combinations. Preliminary results indicate lateral vibration attenuation on the order of 15 dB.

  • 97. Scheuer, Johan
    et al.
    Håkansson, Lars
    Claesson, Ingvar
    Modal Analysis of a Boring Bar using Different Clamping Conditions2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    The internal turning operation is a common metal working process that is usually associated with vibration problems. Boring bars are often long and slender, making them prone to vibration when they are excited by the cutting forces introduced by the material deformation process in boring. The vibration causes degraded surface finish of the machined work piece, decreased tool life of inserts and boring bars, noise and other unwanted effects. Therefore, time-consuming planning and preparation have to be made in order to minimize vibration, affecting the cost of the machining process in the negative direction. It is possible to stabilize boring bars using active vibration control. To be able to do so, the dynamic properties of the bars have to be known in detail. Furthermore, with this knowledge, the results of using prediction tools for relating cutting parameters to cutting results may be significantly improved thanks to more relevant input data into the prediction tools. The effect of different clamping conditions on the dynamic properties of a boring bar's fundamental bending modes has been studied. Modal analysis was performed on a 40 mm-diameter boring bar with 100 mm clamping length and 200 mm overhang, making the L/D ratio 5. The clamping conditions have been varied by use of two different clamping devices. In each clamping device, several different clamping conditions were achieved by using different torque on the clamping screws. Results show that both the eigenfrequencies and the directions of the fundamental bending modes vary considerably due to the clamping conditions used.

  • 98. Sharafi, A.
    et al.
    Khan, Imran
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Zackrisson, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Development and Implementation of an Ad-vanced Remotely Controlled Vibration Laboratory2014Ingår i: proceedings of REV 2014 International Conference on Remote Engineering and Virtual Instrumentation, IEEE Computer Society, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Currently an advanced remotely controlled vibration laboratory is developed and implemented at Blekinge Institute of Technology, Karlskrona, Sweden. The new developments in the laboratory setup will provide users to carry out vibration measurements on a cantilever beam system with remotely adjustable dynamic properties and to estimate dynamic characteristics of it. The dynamic properties of the cantilever beam are remotely modified by attaching structural parts such as a block of mass, a spring mass system and a non-linear spring. In the development of this remote-lab, a number of different approaches were adopted for the production of well-defined experiments. Also, the new prototype laboratory is designed based on finite elements modeling (FEM) and LABVIEW. The test object, attachment mechanism for sub structures, relevant experiments, and proper interface for managing the lab via Internet and many other things have been considered.

  • 99. Smirnova, Tatiana
    et al.
    Larsson, Martin
    Gertsovich, Irina
    Johansson, Sven
    Claesson, Ingvar
    Håkansson, Lars
    Initial investigations concerning modelling of sound propagation in ducts with ANC by means of two-port theory and FEM2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today mechanical ventilation systems are installed in many buildings to handle the ventilation. Such ventilation systems constitute a potential source of unwanted background noise in the buildings. In order to reduce the noise propagating through the ducts passive silencers are normally installed as a part of the ventilation system. However, the passive silencers are relatively ineffective in the low frequency range. A solution can be to use a combination of active noise control (ANC) and passive techniques where the ANC system extends the noise attenuation to include the low frequency noise. The construction of the ventilation systems can vary substantially between different buildings and may contain many different duct parts in different compositions etc. Hence, it may not be trivial to find a cost- and performance efficient installation of an ANC system in a ventilation system, e.g. to find a proper installation position of it and suitable passive silencers to combine it with, finding out if one or several ANC systems should be used, and so on. In order to make the design of a complete ventilation system (including one or several ANC systems) cost- and time efficient, an adequate mathematical model of the duct is required. The purpose of the model is to describe sound propagation in the duct. Such model can be built e.g. based on the two-port theory or by finite element method. In this paper initial investigations concerning modelling of standard duct parts were performed. Simulations were carried out to find parameters such as Noise Reduction etc., using both plane wave two-port theory and finite element modelling. The results of the simulations were compared with measurement results.

  • 100. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Claesson, Ingvar
    Håkansson, Lars
    Lagö, Thomas L
    Modeling a Clamped Boring Bar using Euler-Bernoulli Beam Models with Various Boundary Conditions2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper addresses modeling of a clamped boring bar using Euler-Bernoulli beam theory. Euler-Bernoulli beams with a number of different boundary conditions were used to model a clamped boring bar. Estimates of the boring bar's natural frequencies and mode shapes were produced with each of the boring bar models. The estimates produced by the distributed-parameter system models are compared with eigenfrequencies and mode shapes estimated based on experimental modal analysis of the actual boring bar clamped in a lathe.

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