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Estimation and Pre-Processing of Sensor Data in Heavy Duty Vehicle PlatooningPettersson, Hanna January 2012 (has links)
Today, a rapid development towards fuel efficient technological aids for vehicles is in progress. One step towards this is the development of platooning systems. The main concept of platooning is to let several heavy duty vehicles (HDVs) drive in a convoy and share important information with each other via wireless communication. This thesis describes one out of three subsystems in a project developed to handle the process from raw sensor data to control signal. The goal of the project is to achieve a safe and smooth control with the main purpose of reduced fuel consumption. This subsystem processes the raw sensor data received from the different HDVs. The purpose is to estimate the positions and velocities of the vehicles in a platoon, taking into account that packet-loss, out of sequence measurements and irrelevant information can occur. This is achieved by filtering the information from different sensors in an Extended Kalman Filter and converting it into a local coordinate system with the origin in the ego vehicle. Moreover, the estimates are sorted and categorized into classes with respect to the status of the vehicles. The result of the thesis is useful estimates that are independent of outer effects in a local reference system with origin in the host vehicle. This information can then be used for further sensor fusion and implementation of a Model Predictive Controller (MPC) in two other subsystems. These three subsystems result in a smooth and safe control with an average reduced fuel consumption of approxi- mately 11.1% when the vehicles drive with a distance of 0.5 seconds in a simulated environment. / Dagens utveckling inom fordonsindustrin fokuserar mer och mer påutveckling av bränsleeffektiva hjälpmedel. Ett steg i denna riktning är utvecklingen av platooningsystem. Huvudkonceptet med platooning är att låta flera tunga fordon köra i följd i en konvoj och dela viktig information med varandra via trådlös kommuni- kation och en automatiserad styrstrategi. Detta examensarbete beskriver ett utav tre delsystem i ett projekt som är utvecklat för att hantera en process från rå sensordata till styrsignaler för fordonen. Målet är att uppnå en säker och mjuk reglering med huvudsyftet att reducera bränsleförbrukningen. Det här delsystemet behandlar mottagen sensordata från de olika fordonen. Målet med delsystemet är att skatta positioner och hastigheter för fordonen i konvojen med hänsyn till att förlorad, försenad eller irrelevant information från det trådlösa nätverket kan förekomma. Detta uppnås genom filtrering i ett Extended Kalman Filter och konvertering till ett lokalt referenssystem med origo i det egna fordo- net. Utöver detta sorteras informationen och kategoriseras in i olika klasser efter fordonens status. Examensarbetet resulterade i användbara skattningar oberoende av yttre om- ständigheter i ett lokalt referenssystem med origo i det egna fordonet. Denna information kan användas vidare för ytterligare sensorfusion och implementering av en modellbaserad prediktionsregulator (MPC) i två andra delsystem. De tre delsystemen resulterade i en mjuk och säker reglering och en reducerad bränsleför- brukning med i genomsnitt 11.1% då fordonen körde med 0.5 sekunders avstånd i en simulerad miljö.
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LIGA cavity resonators and filters for microwave and millimetre-wave applicationsMa, Zhen 06 December 2007 (has links)
High performance microwave cavities for various circuits in the front-end of transceivers such as filters, diplexers, and oscillators have conventionally been built with rectangular or
cylindrical metallic waveguides, which typically have low loss, high quality (Q) factor, and higher power handling capability. However such waveguide cavity based circuits made by traditional metal machining techniques tend to be costly, particularly for complex multiple cavity based circuits, and not well suited to high volume commercial applications and integration with planar microwave integrated circuits. As commercial transceiver applications progress toward higher microwave and millimetre-wave frequencies, the use of waveguide based circuits for compact, highly integrated transceivers is becoming feasible, along with an increasing need for cost effective batch fabrication processes for realizing complex metallic cavity circuits without sacrificing structural quality and performance. It is expected that significant advancements in both microwave performance and integration will be achieved through the development of novel technologies for realizing vertically oriented three-dimensional (3-D) structures.<p>Although improvement has been made on increasing the resonator Q factor by exploiting silicon micromachining and low-temperature cofired ceramics (LTCC) techniques, there are some drawbacks inherent to silicon cavity micromachining and LTCC technology, including non-vertical sidewalls, depth limitations, and surface roughness for the silicon resonator, and dielectric and radiation loss for LTCC resonator.<p>Polymer-based fabrication is a promising alternative to silicon etching and LTCC technologies for the batch fabrication of ultra-deep microwave cavity structures. In particular, deep X-ray lithography (XRL), as part of the LIGA process, is a microfabrication technology for precisely structuring polymers, and is increasingly being applied to RF/microwave microstructures. In addition to precise patterning capabilities, deep XRL is able to structure ultra-deep cavities due to the penetration ability of hard X-rays. Cavities of several millimetres are possible in a single lithographic exposure, and with excellent sidewall quality, including verticality near 90 degrees and surface roughness on the order of tens of nanometres. These structured polymers are subsequently used as electroforming templates for fabricating metal structures with correspondingly good sidewall quality.<p>This thesis investigates the possibility of realizing high-Q cavity resonators and filters at microwave frequencies using the LIGA microfabrication process. Finite element method (FEM) electromagnetic simulation results based on the cavity models representing different fabrication conditions show that smooth LIGA cavity structures result in promising Q improvement over silicon and LTCC structures. And the potential advantages of LIGA resonators are more dramatic with cavity height and increasing operating frequency. Deep polymer cavity structures (1.8 mm) fabricated using deep XRL demonstrate excellent sidewall verticality in the PMMA structure, with only slight shrinkage at the top surface of 8.5 2.5 mm in either lateral dimensions. This corresponds to sidewalls with verticality between 89.82o and 89.9o. The structure polymers are subsequently used as templates for metal electroforming to produce cavity resonators. The performance of the resonator is measured in a planar environment. A RT/duroid6010 soft substrate patterned with coupling structures forms the sixth side, and thus completes the cavity. Despite the rather crude test assembly for the sixth side made by clamping, the measured resonator has a high unloaded Q of 2122.2 85 at the resonant frequency of 24 GHz, indicating that LIGA cavities are especially promising for high performance applications. <p>The relatively simple, single-step lithographic exposure also facilitates extension to more structurally complicated waveguide and multiple cavity-based circuits. This research work also proposes a high performance ``split-post' 3-pole cylindrical post coupled Chebyshev bandpass filter suitable for LIGA fabrication. In addition to potentially batch fabricating such a filter lithographically by exposing the entire waveguide depth in a single exposure, the filter structures composed of three cavities with metallic multi-post coupling would be extremely difficult to fabricate using traditional machining techniques, due to the extremely fine post structure and high vertical aspect ratio required. However, these types of structures could be ideal for LIGA fabrication, which offers sub-micron features, aspect ratios of 100:1 or higher, resist thicknesses of up to 3 mm, and almost vertical and optically smooth sidewalls. Also, representative LIGA sidewall roughness is used to predict very low loss and high performance, suggesting that complicated structures with multiple resonator circuits and high internal components with high aspect ratios are possible.
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Synchronization of weak indoor GPS signals with doppler frequency offset using a segmented matched filter and accumulationTang, Bruce 29 June 2009 (has links)
Recent government regulations for Enhanced 911 locating of wireless handsets require accuracy to within 50 and 300 meters. Two technologies under consideration are triangulation using existing wireless base stations and location using global positioning satellites (GPS). Satellite positioning is the leading candidate, however, reception of GPS signals within large buildings is difficult and considerable research is devoted to this topic. Conventional GPS receivers require line of sight to at least four satellites and, under outdoor conditions, the expected signal level is about -160 dBW. Within large buildings, detection is very difficult because there is high thermal noise and some satellite signals can be attenuated to less than -185 dBW while others can suffer little attenuation. In order to construct the pseudo-ranges necessary for position finding, the receiver must synchronize to the incoming codephase of each satellite and must operate with substantial Doppler frequency offset caused by satellite motion.<p>
This thesis investigates the application of a parallel non-coherent spread spectrum synchronizer previously implemented as a very-large-scale integration (VLSI) circuit. The circuit processes one millisecond of incoming signal and uses a segmented matched filter (SMF) by which the segmentation provides some tolerance to Doppler shift. The thesis presents simulation results of averaging for tens of seconds. Through simulation, the SMF is compared with a transversal matched filter (TMF) under conditions of no Doppler shift; coherent and non-coherent integration are discussed. The simulation is conducted at 290 K (17°C) such that the Boltzmann noise is -204 dBW/Hz, with a GPS signal bandwidth of 2 MHz and signal level of -185 dBW, and the receiver input signal-to-noise ratio (SNR) is -44 dB.<p>
The SMF is applied using differing segment lengths to high-sensitivity GPS data from indoor and urban simulated GPS data. The results demonstrate the SMFs ability to tolerate Doppler frequency offsets while allowing for long integration times to detect the weak GPS signals.
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Study on Digital Filter Design and Coefficient QuantizationZhang, Shu-Bin 27 July 2011 (has links)
In this thesis, the basic theory is convex optimization theory[1]. And we study
the problem about how to transfer to convex optimization problem from the filter
design problem. So that we can guarantee the solution is the globally optimized
solution. As we get the filter coefficients, we quantize them, then to reduce the
quantization bits of the filter coefficients by using the algorithm[2]. At last, we try
to change the sequence of quantization, and compared the result with the result of
the method[2].
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Digitally Assisted Multi-Channel ReceiversPentakota, Krishna Anand Santosh Spikanth 2010 August 1900 (has links)
This work presents a data estimation scheme for wide band multi-channel charge
sampling receivers with sinc filter banks together with a complete system calibration and
synchronization algorithm for the receiver. A unified model has been defined for the
receiver containing all first order mismatches, offsets and imperfections and a technique
based on least mean squares algorithm is employed to track these errors. The performance
of this technique under noisy channel conditions has been verified. The sinc filter bank is
compared with the conventional analog filter banks and it is shown that the sinc filter banks
have very low computational complexity in data estimation
Nextly, analytical tools for the design of clock-jitter tolerant multi-channel filterbank
receivers have been developed. Clock-jitter is one of the most fundamental obstacles
for the future generation of wideband receivers. Additionally all the trade-offs and
specifications of a design example for a multi-channel receiver that can process a 5 GHz
baseband signal with 40 dB of signal-to-noise-ratio (SNR) using sampling clocks that can
tolerate up to 5 ps of clock-jitter standard deviation are presented. A novel bandwidth
optimization technique has been presented. As a part of it the bandwidth of the filters present in each path is optimized thereby improving the performance of the receiver further
in the presence of sampling clock jitter. The amount of bandwidth reduction possible
depends on the order of the filter and the noise amplification provided by the reconstruction
matrix. It has been shown that 3rd order filters of bandwidth 1 GHz can be replaced with 1st
order filters of bandwidth 100 MHz without any depreciation in the output resolution,
implying huge power savings.
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The Median Filter Combining with Trend Diction for Edge-Preserving Noise Reduction in Image ProcessingTsai, Wen 08 September 2004 (has links)
In most of the optical interferometry techniques, one often get interferometric fringe patterns which include noises, and these noises will cause analysis difficulty. The method of median filter is used to sort the data in the region, and use median value to replace the center value of the region. Therefore, the median filter technique can find central tendency of the region, and less affected by the presence of a minority of aberrant value. So the median filter technique is used frequently in image processing of many optical fringe patterns
The median filter technique is effective in removing noise with high frequency, but tends to smooth out details such as summits if the window size is large. So there are many improved methods developed corresponding to different properties of signal. Even though each of the improved methods has different considerations, such as to consider different integer weights, or different window size etc., their purposes are all the same, that is to make results more accurately. On the basis of these viewpoints, this thesis will use concept of least¡Vsquares fitting on 2-D interferometric fringe patterns. By finding the trend of the region, and avoid unnecessary signal consideration, make the results more accurately.
In order to study the effect of the proposed technique, two sets of fringe patterns obtained from the phase-shifting speckle interferometry will be used as examples. They showed that the proposed technique presents a better result than traditional technique.
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Performance Study on the Treatment of the vent gas of the Fermentation process of Compost by Biotrickling Filtersshih, ya-ru 28 June 2006 (has links)
Kitchen waste compositing plants emit odorous gas streams with sulfur-, nitrogen-, and oxygen-containing compounds and other hydrocarbons. A pilot-scale biotrickling filter with a space of 0.3 m square and 1.0 m height packed with fern chips was used for removing the odorous components from the kitchen waste compositing gas. An average weight ratio of ¡§kitchen waste: bulking material: seeding compost¡¨ of 90:4.5:5.5 was used to prepare the compositing material for producing the odorous gas for test. The kitchen waste was composed of residual material from food preparation and meal wastes. The bulking material was either wood trimmings or dried leaves and the seeding material was a blend of manure and bird feather compost. Experiments indicate that the composting material could develop to 32-55 oC during a composting period of 6 weeks and the vented gas contained ammonia, amines, mercaptans, and hydrogen sulfide to maximum values of 700, 1,000, 53, and 1.0 ppm, respectively. A maximum odor concentration of 23,000 was obtained and the odor intensity was closely related to mercaptans in the vented gas.
Results indicate that by using the bio-treated effluent of the school-owned domestic wastewater treatment plant as a supplemental water and nutrition sources for the biotrickling filter, 0.5-5 and 1-15 ppm of ammonia and amines, respectively, in the introduced odorous gas could completely be removed at conditions of empty-bed-retention-times (EBRT) of 15 s and liquid/gas flow ratio (L/G) of 0.003 m3/m3. Particularly, with an EBRT of 7 s at a fixed L/G of 0.002, 99.7% of odor intensity (dilution to the threshold ratio, DT) in the influent gas with a DT of 5,500 could be removed.
Instead of effluent wastewater, by supplementing tap water with 25 mg/L of milk powder to the biotrickling filter, results indicate that with an EBRT of 7 s at a fixed L/G of 0.002, 99.7% of odor intensity in the influent gas with a DT of 13,000 could be removed. Milk powder supplementation gave better performance than the effluent wastewater one.
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Investigations of Channel Estimation Using Kalman Filter for OFDM Systems in Time Varying ChannelChou, Hsin-Heng 23 August 2006 (has links)
In this thesis, a modified Kalman filter is proposed for time varying channel estimation in orthogonal frequency division multiplexing (OFDM). The proposed scheme adopts pre-coding scheme and minimum mean squared error (MMSE) equalizer to improve system performance. By using pre-coding schemes, information can be protected by signal diversities, which prevent Kalman filter to disperse due to erroneous data signals. In this investigation, the proposed system architecture is verified by using simulation experiments. Simulation results demonstrate that the proposed schemes substantially improve system performances under verious channel conditions.
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Stress induced wavelength shift of thin WDM thin film filterJiang, Jr-hau 06 July 2007 (has links)
Stress induced wavelength shift of thin film filter (TFF) were investigated. The substrate thickness of the TFF were greatly reduced by lapping to enhance the effects of stress. For CWDM TFF, no significant
wavelength shift was observed by reducing their substrate thickness from 300 £gm to 70 £gm. Further, thermal stress caused by direct heating the thin
TFF to 100¢J shows no effective changes of their optical characteristics. On the other hand, wavelength shifts induced by mechanical stress after reducing the substrate thickness of the DWDM TFF were observed. The maximum wavelength shift 3.8 nm was measured by lapping the substrate from 1mm to 120 £gm. Additional wavelength shifts of 3.5 nm were
observed from the thin DWDM TFF if a lens fiber was brought into close contact with the thin DWDM TFF and was pushed forward for a distance of 45 £gm.
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Treatment of Styrene and Acrylonitrile in Air Streams by Full-scale Biotrickling Filterstu, Amy 20 June 2001 (has links)
Abstract
This research focuses on the performance of a full-scale biotrickling filter (BTF) for treating a vented gas from an ABS (acrylonitrile-butadiene-styrene) resin plant. The BTF was constructed by reinforced concrete with a size of 5 m in width, 9 m in length, and 3.5 m in height. It consists of six individual chambers with packing materials of 4.6m in length and 4.2m in width for each. The vented gas contains styrene (SM) and acrylonitrile (AN) as two major components and has an average flow rate of 43,000 m3/h (720 m3/min) and a temperature range of 40-53¢J.
Three test protocols have been studied to understand the effects of changing scrubbing method, types of packing materials, and amounts of packing materials on the pollutant removal efficacy. Two different instruments (portable FID and laboratory GC) were used to measure the VOC concentrations for both the inlet and outlet of the BTF. Many parameters were monitored for trend analysis, including gas flow rate, empty-bed gas retention time, system temperature, inlet and outlet VOC concentrations, VOC mass flow rate, organic loading, VOC removal efficiency, recirculation water volume, VOC concentration in the recirculation water, and mass flow rate of the recirculation water. These data were analyzed for discussing the technical feasibility of using BTF as an air pollution control unit for petrochemical industry.
Experimental results showed that the third protocol using PVC packing materials (installed with 4.6m in length, 4.2 in width, and 0.6m in height for each of the 6 chambers) was the best setup for the target VOC removal. Without adding any special seed and supplementary nutrient, effluent of the wastewater treatment unit of the plant was introduced into the BTF as the recirculation water (pH 7-8.5, volumetric flow rate 15-30 m3/h, and temperature was 35-50¢J). A range of VOC removal efficiencies of 8.6-41% (equivalent to volumetric elimination rates of K = 41-949 g/m3.h) was obtained with loadings of L = 469-3015 g/m3.h based on the GC data. The elimination rates were 41-949 and 27.4-562 g/m3.h, respectively, for AN and SM corresponding to loadings of 121-1104 and 818-1756 g/m3.h for the two components. An average removal efficiency (K/L) of 24.5% was obtained for AN and SM regardless of the magnitude of the loading. Distribution of VOC removal was 13% by biofilms and the rest by the recirculation water. Microbiological tests revealed that Nematods was the most dominating species at high loadings and Trachelophyllum sp. was the most dominating species at lower loadings. It was also estimated that a total operating cost of NT$ 23,920/day is required and that is equivalent to a cost of NT$ 34.1 for eliminating 1 kg of VOCs from the waste gas.
The data showed that the VOC loading (469-3015 g/m3.h, average 1808 g/m3.h) to the BTF was much higher than the normal design value of 30-60g/m3.h. It is suggested that a pre-treatment unit should be added into the system to lower the organic loading before the waste stream enters the BTF. In addition, the makeup recirculation water should be increased to foster the bacteria growth and to improve the absorption of VOCs from the waste gas.
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