基于FPGA平台构建汽车辅助驾驶系统算法

辅助驾驶系统开发面临的挑战 汽车辅助驾驶(DA)系统工程师通常使用PC模型来创建复杂的处理算法,以便实现高度可靠的自适应巡航控制、车道偏离警告及行人检测等功能.开发人员高度重视PC算法模型,因为这种模型使他们能够尝试使用并快速评估不同的处理算法.不过,说到底,还是需要一款设计合理的电子硬件解决方案,来实现经济有效的大规模生产与部署.     

Pedestrian detection for driver assistance using multiresolution infrared vision

This paper describes a system for pedestrian detection in infrared images, which has been implemented on an experimental vehicle equipped with an infrared camera. The proposed system has been tested in many situations and has proven to be efficient and with a very low false-positive rate. It is based on a multiresolution localization of warm symmetrical objects with specific size and aspect ratio; anyway, because road infrastructures and other road participants may also have such characteristics, a set of matched filters is included in order to reduce false detections. A final validation process, based on human shape's morphological characteristics, is used to build the list of pedestrian appearing in the scene. Neither temporal correlation nor motion cues are used in this first part of the project: the processing is based on the analysis of single frames only.     

Hot spot analysis during thermal shutdown of SOI BCDMOS half bridge driver for automotive applications

The thermal distribution in large DMOS output transistors of a half-bridge driver IC fabricated in smart-power SOI technology is investigated by the backside transient interferometric mapping (TIM) technique during its thermal shutdown process. The TIM measurements uncovers four hot spots, where the temperature exceeds the limit of the built in temperature sensor. This explains the specific failure mode which was identified during accelerated reliability tests. The TIM results are complemented by temperature measurements with the build-in temperature sensors.     

Design and analysis of receiver filters for multiple chip-rateDS-CDMA systems

As multimedia applications proliferate, there is a desire to provide wireless transport to information streams with inherently different data rates. Direct-sequence code division multiple access (DS-CDMA) is a natural multiple-access strategy for multiple data-rate systems. Previous work on multirate DS-CDMA receivers has focused on signal-processing techniques, which detect all users of all rates simultaneously. In the current work, multirate users have multiple bandwidths. Thus, it is proposed to exploit bandwidth differences to achieve frequency-based rate separation followed by single-rate detection schemes. Such a methodology enables a tradeoff between receiver complexity and performance. The performance of the proposed filters and receivers are derived for both a modified matched filter and modified decorrelator employing rate separation. The performance of a multirate CDMA overlay system is evaluated. In addition, chip pulse shaping for wide-band users is developed to improve performance for narrow-band users for the overlay system     

Data-transmission filters for duobinary systems

Some practical design information is given for duobinary lowpass filters with minimal intersymbol interference. It in cludes design values (poles and zeros) for two realisable filters, and their associated responses. A comparison with Nyquist I filters is also presented.     

Electrical environmental characteristics for automotive electric systems

The electrical environment is one of the most important factors in the design of high reliability electronic systems mounted on automobiles. Studies were made of the generation mechanisms and characteristics of both transients and high-frequency conducted noise generated in automotive electrical components. The high-frequency conducted noise data were obtained in terms of amplitude-frequency through real-time statistical treatment of the acquired data. The most important transient for automotive electronic systems has been found to be the alternator load dump transient caused by battery disconnection, and the most influential high-frequency conducted noise is caused by contact breaking. The high-frequency conducted noise characteristics can be expressed in the amplitude-frequency relation in the frequency range of 100 kHz-80 MHz.     

Learning bayesian classifiers for scene classification with a visual grammar

A challenging problem in image content extraction and classification is building a system that automatically learns high-level semantic interpretations of images. We describe a Bayesian framework for a visual grammar that aims to reduce the gap between low-level features and high-level user semantics. Our approach includes modeling image pixels using automatic fusion of their spectral, textural, and other ancillary attributes; segmentation of image regions using an iterative split-and-merge algorithm; and representing scenes by decomposing them into prototype regions and modeling the interactions between these regions in terms of their spatial relationships. Naive Bayes classifiers are used in the learning of models for region segmentation and classification using positive and negative examples for user-defined semantic land cover labels. The system also automatically learns representative region groups that can distinguish different scenes and builds visual grammar models. Experiments using Landsat scenes show that the visual grammar enables creation of high-level classes that cannot be modeled by individual pixels or regions. Furthermore, learning of the classifiers requires only a few training examples.     

MAC units for matched filters in DS-CDMA systems

High data rates in wireless radio environments are becoming common. Current system designs are inadequate to meet the speed requirements that are anticipated in newer services. The computational complexity in the subsystems of wireless radio increases in direct proportion to the data rate. In this correspondence, we propose alternative multiply accumulate (MAC) units for the pulse shaping filters that use a new representation for their coefficients. Consequently, these new structures are fast, efficient and dissipate less power. The filters proposed take into account constraints, such as, intersymbol interference, response characteristics etc. in their design methodology     

采用混合t分布粒子滤波器的视觉跟踪

由于目标数量的变化,观测数据的岐义性和目标间的遮挡,多目标视觉跟踪问题面临多种困难.基于目标分布的有限t分布混合模型提出了一种混合t分布粒子滤波器以实现多目标跟踪.在算法中,每个被跟踪目标指派一个独立的粒子滤波器,显式处理当新目标出现在场景中时对应粒子滤波器的初始化,当被跟踪目标消失时,对应粒子滤波器的删除.混合t分布...     

Coupled-microstrip bandpass sine filters for broadbandcommunications systems

A bandpass microwave sine filter using coupled microstrip circuits is described. The filter contains three elements; a coupled line filter which creates the main lobe and zeros, a Butterworth filter to reduce out-of-band energy, and an isolation element. Results For a 2.35 GHz filter matched to a 110 MHz chip rate are shown     

Optimum precompensation filters for IQ modulation systems

We present a technique for digitally precompensating for shortcomings in signal reconstruction filters in an IQ modulation system. Optimum digital precompensation filters are found using least squares (LS) techniques. The optimization problem is formulated in the frequency-domain, and the optimum LS solution is characterized using an eigenanalysis approach     

Synthesis of multiple-ring-resonator filters for optical systems

A method for the synthesis of optical filters consisting of a cascade of N-coupled rings is presented. The procedure is based on the definition of a polynomial whose roots are the zeros of the channel-dropping transmittance characteristic and provides directly the ring electrical lengths and the mutual coupling coefficients. A design example of a Chebyshev-type 6-ring bandpass filter is presented.     

Depth-map-based scene analysis for active navigation in virtual angioscopy

This paper presents a new approach dealing with virtual exploratory navigation inside vascular structures. It is based on the notion of active vision in which only visual perception drives the motion of the virtual angioscope. The proposed fly-through approach does not require a premodeling of the volume dataset or an interactive control of the virtual sensor during the fly-through. Active navigation combines the on-line computation of the scene view and its analysis, to automatically define the three-dimensional sensor path. The navigation environment and the camera-like model are first sketched. The basic stages of the active navigation framework are then described: the virtual image computation (based on ray casting), the scene analysis process (using depth map), the navigation strategy, and the virtual path estimation. Experimental results obtained from phantom model and patient computed tomography data are finally reported.     

Dielectric multilayer thin-film filters for WDM transmission systems

Dielectric multilayer thin-film (DMF) filters for a wavelength-division-multiplexing (WDM) system are discussed. It was found that a 23-layer 3-cavity bandpass-type DMF-filter made of TiO2and SiO2is most suitable for this type of system. An optical multi/demultiplexer employing this type of bandpass DMF-filter is applicable to a two-way WDM transmission system.     

Dispersive properties of optical filters for WDM systems

Wavelength division multiplexing (WDM) communication systems invariably require good optical filters meeting stringent requirements on their amplitude response, the ideal being a perfectly rectangular filter. To achieve high bandwidth utilization, the phase response of these filters is of equal importance, with the ideal filter having perfectly linear phase and therefore constant time delay and no dispersion. This aspect of optical filters for WDM systems has not received much attention until very recently. It is the objective of this paper to consider the phase response and resulting dispersion of optical filters in general and their impact on WDM system performance. To this end we use general concepts from linear systems, in particular, minimum and nonminimum phase response and the applicability of Hilbert transforms (also known as Kramers-Kronig relations). We analyze three different classes of optical filters, which are currently being used in WDM systems and compare their performance in terms of their phase response. Finally, we consider possible ways of linearizing the phase response without affecting the amplitude response, in an attempt to approximate the ideal filter and achieve the highest bandwidth utilization