Today a number of different optical techniques capable of measuring range, velocity or both exist. With recent advancements in laser diode manufacturing, small tunable sources have become available. By modulating current supplied to the laser the optical output frequency can be modulated. If the outgoing modulated light is divided into two parts, a transmitted and a local oscillator part, and a photodiode is used as detector, the frequency difference between the two parts can be obtained directly from the photodiode current. This frequency difference is often referred to as the beat frequency. If triangular frequency modulation is used, both range and radial velocity can be determined from the measured beat frequency. The common name for this technique, which was first implemented using regular radar, is frequency modulated continuous wave (FMCW). The thesis consists of an introduction and five papers. Paper one is a theoretical investigation where contributions from different noise sources are discussed. We have investigated how the signal to noise ratio for the photodiode is affected by how the optical power is divided between the transmitted part and the local oscillator part. Paper number two introduces a new modulation scheme that avoids ambiguity problems resulting from a Doppler shift larger than the frequency shift associated with the range. As a result of this new modulation scheme other benefits are also gained. The modulation scheme was tested and verified in our lab system built with a tunable laser diode and a fiber optic coupler. Paper number three presents a single stage OP-amp solution suited for an FMCW system. Our circuit combines a high gain in the desired frequency region with minimal gain at dc, without using any inductors. The risk of saturation or clipping due to the local oscillator can thereby greatly be reduced. Inserting a high pass filter between the photodiode and the first amplifier stage, to remove the dc level, is often not practical when using a regular current to voltage converter. A cascade of two stages, with a high pass filter between the two, is therefore commonly used. Our solution has similar performance as the cascade solution, but since it uses only one OP-amp, it is less sensitive to external disturbances. Paper number four and five deal with a common problem in an FMCW systems where the optical frequency is used as the carrier wave, and the modulation is obtained by modulating a current to the laser. For optimum performance, the frequency sweep should be as linear as possible, but due to thermal effects, a linear current ramping seldom results in a linear frequency ramping. At lower modulation frequencies, below 1 MHz, the temperature behaviour of the laser has a large influence on the frequency behaviour. To model the frequency behaviour we hence started by investigating the thermal behaviour. This work is presented in paper four. The goal is to obtain a model for the frequency behaviour with respect to changes in the laser drive current. In paper five, this model has been tweaked a bit and is used to obtain modulation currents that gives a linear frequency ramping. / <p>Godkänd; 2004; 20061025 (haneit)</p>

This thesis concerns localization and control of mobile robots using range measurements from optronic sensors, in particular scanning time-of-flight lasers. The thesis covers the localization algorithms, on-line sensor calibration and tele-operation for semi-autonomous control of mobile robots. A real-world application of an autonomous mobile robot equipped with an arm for surface finishing operations is also developed. The Range Weighted Hough/Radon transform is introduced for robust detection of walls and extraction of geometric parameters. Thus a robot can automatically create a map of its environment and update it using an extended Kalman filter. The required association of observations with the map features uses a Bayesian classifier. New walls are added to the map as they are observed and classified as new. Navigation is performed with typical fluctuations of 1 cm and 1 degree (standard deviation) at speeds of 0.5 m/s. The navigation is robust even in cluttered environments and with several persons moving around. Sheet-of-light range cameras have also been tested for mobile robot navigation. A calibration algorithm for simultaneous calibration and localization integrates the calibration into the localization system. The only absolute reference needed by the calibration algorithm is the relative motion of the robot. The resulting system performs calibration during normal operation without lowering the localization performance. The algorithms above were applied to two applications: - A mobile robot capable of autonomously spray-plastering the walls and ceiling of a room. The prototype was successfully tested at construction sites. - A semi-autonomous robot tele-operated using tele-commands. The tele- commands include navigation along corridors, through open doors, following walking persons and automatic map generation of the remote site. / <p>Godkänd; 1998; 20061122 (haneit)</p>

This thesis presents contributions to work for better methodologies for addressing Electromagnetic Compatibility (EMC) issues. In particular measurement methods are reviewed and devised for acquiring data on barriers used for EMC. Such data is used for characterization, modeling and model verification of barriers. The concept of EMC barriers is introduced as a general view of filter components, separation of conductors (crosstalk problems), electromagnetic shielding etc. The aim is to find methodologies to help engineers to identify EMC problems and to include the management of EMC in the design of a electrical circuit in a practical and effective manner. Methodologies for generation of EMC barrier modeling techniques have been developed. This work have resulted in design tools for electronic design engineers to include EMC considerations at an early design stage of a new product. Problems with existing barrier characterizing measurement methods have been identified. By comparison of far field and near field shielding effectiveness measurement methods, data for shielding thermoplastic materials was acquired. Considering the purpose of studied shielding materials in an application the usefulness of the far field shielding effectiveness measurement method is questioned. EMC barrier measurement methodologies of interest in this thesis includes shielding effectiveness measurements, transfer impedance measurements, scattering parameter measurements, measurements of material permittivity and permeability and near field scanning techniques for analysis of current distributions. / <p>Godkänd; 2004; 20061029 (ysko)</p>

Power consumption is an important design constraint for circuits used in portable devices. In this thesis an analytic approach to minimize the power dissipation of Binary Decision Diagram (BDD) mapped digital circuits is presented. Our synthesis approach combines logic minimization, low power optimization and mapping to a Pass Transistor Logic (PTL) multiplexor circuit. The low power optimization procedure utilizes statistical properties for the input signals to reduce the estimated power dissipation. For BDD mapped circuits, the variable order of the underlying BDD heavily affects both the number of nodes (size) and the switching activity for each node. In turn, static power dissipation increases with circuit size, while dynamic power dissipation increases with switching activity and capacitive load. The capacitive load for a mapped node is modeled as the number of incoming edges. The cost model based on a PTL mapping is applied in a heuristic optimization procedure iteratively improving the overall cost by local variable exchanges. Three novel BDD based approximative methods for switching activity estimation are introduced. The first method assumes no temporal signal correlation. The second method assumes temporal correlation on the input signals only. Both of these simplifications allows the low power optimization to be carried out exclusively by local BDD operations. The third method accounts also for temporal correlation of internal signals in the circuit. The latter approach is refined at the cost of computation complexity, whereas the optimization is no longer local. The mapped circuits have in simulation (using a commercially available process model) shown reduced power dissipation characteristic. Furthermore a technique for extracting signal properties from synchronous Finite State Machine (FSM) implementations is described. All computations are performed using decision diagram techniques. As an application of this method, the extracted information is utilized in the presented low power synthesis procedure. Experimental results on MCNC (combinational) and ISCAS89 (sequential) benchmarks show significant reductions of the estimated power dissipation. The ISCAS89 results how an average reduction of 40 percent and up-to 90 percent on individual benchmarks. / <p>Godkänd; 2001; 20070313 (ysko)</p>

This thesis is on mobile robot navigation using range sensors. The two sensors types used are time-of-flight lasers and sheet-of-light range cameras, both giving densely spaced range measurements. Map generation and navi gation are achieved in indoor environments, even when there are lots of disturbing objects giving cluttered range measurements. The walls are observed in the range scans using the Range Weighted Hough Transform, (RWHT) and the estimates of the map and the robot position are maintained during motion using Extended Kalman Filtering (EKF). The calibration of sensor parameters during operation uses the relative motion given by the incremental encoders on the wheels as the absolute calibration reference. Matching of observations to previous estimates are performed using a deci sion directed classifier. The algorithms can be used both to build a map, or during navigation using an existing map. The algorithms have been verified in several experiment with the range sensors onboard actual mobile robots. The size of a large room was estimated with a standard deviation of 1 cm. The robot navigates autonomously through an open door detected by the laser. The accuracy during passage was 1 cm at a speed of 0.5 m/s. The trajectory is perpendicular to the wall within 0.5 degrees. In one experiment the robot created a map of its environment while moving at speeds from 0.5 to 1 m/s. The standard deviation in the esti mated map dimensions for a series of tests were 1 to 2 cm and 1 degree. The navigation system has also been used for an autonomous plastering robot with automatic planning to include doors and windows. The navigation is very robust against both outliers in the measurements and disturbing objects. It is not seriously disturbed even when most of the walls are occluded and there are several persons moving around during operation.

The subject of Electromagnetic Compatibility (EMC) is introduced. A short overview of the regulatory EMC requirements in Europe and in the United States is presented. An explanation is given why it is important for people in the electronics business to understand the need for EMC regulations. Electromagnetic shielding is a often used as an electromagnetic barrier for attenuation of disturbances from radiating sources. An orientation over the concept of electromagnetic barriers is presented. Ways to characterize barriers are presented and measurement methods are reviewed. Results from transfer impedance measurements show that conductive gaskets made of tin coated stainless steel, can give as good shielding performance as gaskets made of beryllium copper in the entire frequency interval of the investigation. The results show that the difference in shielding performance with gaskets made of tin coated stainless steel and of beryllium copper can be insignificant compared to the influence of a very small change in contact pressure. The difference between gaskets with and without tin coating is small with beryllium copper as base material. With stainless steel as base material the difference is about 10dB at 2MHz and less at higher frequencies. A method to describe electromagnetic barriers such as filters, shielded cables and connectors etc. with circuits consisting of linear discrete components is presented. By comparing a barrier with a multi-conductor transmission line a lumped circuit can be constructed where component values are designated by the per-unit length transmission line parameters. For barriers that cannot be viewed as transmission lines a method for determining equivalent circuits outgoing from measured S-parameters has been developed. Different measurement fixtures were constructed in order to obtain accurate S-parameter values. Derived models have been used in SPICE simulations and validated by comparison with measurements. The current distributions on the surface of a printed log periodic dipole antenna (LPDA) have been investigated. A position scanned magnetic field probe was used to obtain values of the magnitude and phase of the magnetic field at each point of the scan. From the measurements the time variant instantaneous values of the magnetic field and the instantaneous currents on the LPDA were derived. The wave nature of the current distribution can be readily observed and problems with the design such as standing waves on the feeder lines are highlighted. Measured current distributions are compared with predicted distributions obtained from Method of Moments (MOM) analysis of the LPDA structure. Measured and predicted far field radiation patterns are also compared. / <p>Godkänd; 2000; 20070318 (ysko)</p>

Propelled by increased global awareness and demand for clean energy systems, there is a growing trend in transportation, utility, industrial, and residential applications towards the utilisation of power electronic systems with enhanced power ow controllability and eciency. Examples of power electronics applications include terminal converters in high-voltage direct Current (HVDC) transmission; exible AC transmission systems (FACTS); and converters to interface alternative energy systems such as wind turbines to the grid, variable-speed motor drives in pump systems, vehicular propulsion systems, air-conditioners, and refrigerators.The basic functionality of power electronic components is achieved by switching high voltages and currents. Recent advancements in semiconductor technology have significantly improved the current and voltage handling capabilities and the switching frequencies of power electronic devices. However, this rapid switching of high currents and voltages in turn generates electromagnetic disturbances that could distort the functionality of the power electronic equipment and other devices in the vicinity. Electromagnetic compatibility (EMC) regulations and functionality requirements impose restrictions on the design of power electronic systems. To design robust power electronic systems, a thorough understanding of the related electromagnetic issues is required.This thesis focuses on the EMC characterisation of power electronic systems and contains two major phases.In the first phase, the high frequency characterisation of air-core reactors was considered. Air-core reactors are typically used in power systems for current limiting, ltering, shunting, and neutral grounding applications. It is of interest to understand the behaviour of air-core reactors in the presence of high frequency signals, especially from switching operations in the power electronic components. Using the partial element equivalent circuit (PEEC) approach, air-core reactor models, helpful in design and electromagnetic analysis, were created. The PEEC models were able to predict the current and voltage distributions and the eventual electromagnetic emissions at different frequencies. The second phase involved the characterisation of electromagnetic emissions from PWM drives using both modeling and measurement. A case study was performed on a prototype hybrid electric vehicle (HEV). Typically, emissions from PWM drives are expected at harmonics of the PWM switching frequency (fc) and harmonics of the fundamental frequency (f0) of the phase voltages. In this study, it was established that space vector PWM drives generate low-frequency pulsating (LFP) emissions at a frequency of 6f0. The switching of voltage vectors generates common mode current spikes because of the presence of stray capacitances and inductances. The spikes superpose across sector boundaries, forming spikes of double or triple amplitude that constitute the LFP emissions. The amplitudes of these ulsations were shown to be dependent on the drive parameters, such as the load, the speed, and the voltage slew rates. These common mode emissions enhance the emissions at harmonics of the switching frequency, create low-frequency emissions, and when injected into an electric motor, could cause torque pulsations and speed uctuations that may degrade drive functionality. Measurements from an HEV prototype show the LFP emissions, and theoretical models were developed to characterise them. / <p>Godkänd; 2010; 20100826 (mathen); DISPUTATION Ämnesområde: Industriell elektronik/Industrial Electronics Opponent: Professor Mats Alaküla, Lund University and Volvo Car AB Ordförande: Professor Jerker Delsing, Luleå tekniska universitet Tid: Torsdag den 30 september 2010, kl 09.30 Plats: A1514 Demostudion, Luleå tekniska universitet</p> / EM Karaktärisering och Modellering av Elektriska Hybriddrivsystem

The project aim is to evaluate if vibrations, in a train bridge, can be used in an on-demand bridgemonitoring system, for vibrational stress, using a technique called EcoSense. The EcoSense architectureis used to reduce the power consumption of sensors by only allowing them to use power when a desiredmeasurement is wanted (e.g. a train passes). The main task is to analyse how such a system can bebuilt to perform as efficiently as possible. The system should be tested at Lidingö bridge in Stockholm.The resulting circuit was successful to be used as an on-demand switch for a sensor on Lidingö bridge.Testing and evaluation of different specifications of the circuit was done. The final conclusion is thatEcoSense is applicable for bridge vibrational sensing and designs can be tailored to fit the specificationsof a bridge.

Modern Street Lights (MSL) has a LED-lighting that suddenly fails during use. The first part in the project is to find the cause to the failure. In addition, MSL has a new idea for a lamp post. The second part in the project is to develop an electric structure for the lamp post. An EMC test is conducted to see if the EMC Directive can be met. The process of a CE marking of the prototype is summarized in a CE guide. The analysis consists of collecting electrical data of the broken LED-lighting. The same analysis is performed on a functioning LED-lighting. The functioning LED-lighting acts as a reference in the analysis. A comparison between these shall provide a basis for detecting the cause of the accident at the broken LED-lighting.The development of a new LED-lighting is based on a preliminary study as well as the demands of MSL on the prototype. The EMC test is carried out in the electronics center at Halmstad University. The result of the analysis shows a deviation in the design and in the voltage drop of the LED-component. Burns on the LED-components indicates that the circuit has been stressed with too much current. A normal distribution shows that the LED-components of the broken LED-lighting do not have the same stability as in the functioning LED-lighting. The conclusion is that too much current has floated in the circuit.  The cause is probably made of external voltage increases. The result over developed LED-lighting proves to achieve the client's prototype requirements. The prototype does also achieve a part of the EMC requirements. A future work is to optimize the electrical design. The heat release from the resistor has to reduce. A solution is to find a CE-marked drive that matches the electrical data of the LED-luminaire. This increases the total efficiency.

Studien är utförd på Luleå Energi Elnät AB (LEEAB) och handlar om elnätsautomation i ett markkabelnät i Luleås stadskärna. Examensarbetet, 15 högskolepoäng, är den avslutande delen i utbildningen Högskoleingenjör inom Elkraftteknik via Luleå tekniska universitet. Elnätsautomation är ett brett begrepp som kan handla om fjärrstyrda lastfrånskiljare/effektbrytare till helautomatiserade elnät. För de flesta elnätsföretagen är det varken ekonomiskt hållbart eller nödvändigt att ha ett helautomatiserat elnät. Det går endast att spekulera om att det kommer ställas högre krav på elnätet men om kraven höjs är det en fördel om elnätet är grundat för elnätsautomation. Eftersom elnätet byggs för fyrtio år framöver kan stora kostnader undvikas genom att ha en grundprincip för vad som ska finnas med vid om-/nybyggnation av nätstationer. Elnätsautomationens syfte är att förkorta avbrottstiderna. SAIDI/SAIFI har undersökts. SAIDI är ett systemindex för genomsnittliga avbrott i elnätet, indikerat i minuter per år per kund. SAIFI är ett systemindex för det genomsnittliga antalet avbrott i elnätet, indikerat i antalet avbrott per år per kund. Slutsatsen efter studien är att SAIDI kan förbättras med hjälp av enklare elnätsautomation men också av en helautomatiserad lösning. SAIFI kan förbättras vid helautomatiserade lösningar, om det leder till att avbrottstiden underskrider tre minuter. Eftersom det som tar längst tid vid ett avbrott i markkabelnät är att hitta felstället, blir feldetekteringen den viktigaste aspekten inom elnätsautomation. Lösningsförslag från Protrol och Netcontrol har presenterats och jämförts. Protrols lösning är billig, kommer som ett färdigt paket med styrning, detektering och eventuellt logik för helautomation, den är också enkel att implementera i befintliga stationer. Netcontrols lösning är dyrare. Den har styrning, feldetektering, elkvalitetsmätning och skyddsfunktioner där det går att beställa de funktionerna som behövs.    För bäst resultat är det en fördel att prova lösningarna, förslagsvis en lösning på varsin slinga. En rekommendation är att implementera lösningen vid om-/nybyggnation av nätstationer för att underlätta installation och få ner kostnaderna. För att lägga grunden för elnätsautomation är rekommendationen att förbereda för optisk fiber, genom att gräva ner optorör om möjlighet finns, och installera motordon till lastfrånskiljare/effektbrytare. / The study is performed at Luleå Energi Elnät AB (LEEAB) and concerns electrical grid automation (distribution automation) in a cable network in the center of the city of Luleå in northern Sweden. The thesis is the final part of the bachelor’s degree in Electric Power Engineering at Luleå University of Technology. Electrical grid automation is a broad concept that can range from remote-controlled load-switches/circuit breakers up to fully automated power grids. For most power companies, it is not economically viable or necessary to have fully automated power grids. If the demands for the power grid increase, it is an advantage to have a foundation for electrical grid automation. The power grid is planned to last for forty years. Big savings can be made by having a basic principle how to build new or reconstruct distribution substations (MV/LV). The purpose of electrical grid automation is to shorten power interruptions. The internationally standardized indices SAIDI and SAIFI have been used in this study. SAIDI is the average duration of the interruptions, expressed in minutes per year and customer. SAIFI is the average number of interruptions, expressed in number of interruptions per year and customer. The conclusion from the study is that SAIDI is improved by electrical grid automation and a fully automated solution. SAIFI could be improved by a fully automated solution, if it causes the interruption time to decrease to less than three minutes. In case of a power interruption in an underground cable grid, locating the fault is what takes the longest. Therefore, locating the fault is the most important task in electrical grid automation. Two different solutions, from Protrol and Netcontrol, have been presented and compared in the study. The solution from Protrol is inexpensive, comes as a complete package of control, detection and possible logic for full automation; it is also easy to implement in existing distribution substations. The solution from Netcontrol is more expensive. The functions for the Netcontrol solution are control, fault detection, power quality measurements and protection functions, where one can order the desired features. For the best results, it is an advantage to try the different solutions, preferably one solution on each network loop. A recommendation for making the installation easier and to save some money is to implement the solution if the distribution substation is about to be replaced or renovated. To prepare for implementation of electrical grid automation a recommendation is to dig pipes for optical fiber and installing mechanism to the load-switches/circuit breakers.