超声测距在汽车倒车中的应用

为了帮助汽车驾驶员实现安全倒车的目的,根据超声波测距的工作原理,采用AT89C52单片机系统、温度传感器及超声波传感器为硬件核心,采用单片机C语言编写程序,设计出一套具有实时超声波速度修正及可多方位进行检测扫描的超声波测距系统.实现汽车在倒车过程中一旦接近有障碍物时,立刻自动报警并显示出汽车尾部到障碍物距离的功能.     

汽车障碍物检测系统的设计

针对当前汽车事故的频繁发生,为有效降低事故率,文中介绍了以一种以8051单片机为核心的结构简单、精度较高、测距较长、可靠性较高的汽车障碍物检测报警系统.该防撞报警系统利用超声波测距原理,结合了温度传感器进行实时温度的测量,对行进中的汽车前方的障碍物进行实时测距,并且能及时进行障碍物距离的显示及声光报警处理;该系统比较适合在空气能见度低,汽车倒车及晚间行驶等情况下汽车低速行使过程时使用,文中详细阐述了系统的硬件结构和软件设计.     

移动机器人的超声波测距传感器设计

针对移动机器人研究了一种基于单片机AT89C51作为控制系统的超声波测距传感器,实现其硬件电路设计和软件算法的开发,分析了其系统组成、实验结果及误差。该系统以空气中超声波的传播速度为确定条件,利用反射超声波测量待测距离。结果表明,该设计提高了移动机器人的障碍回避能力及导航方面的精度和可靠性。     

超声波测距语音提示系统的研究

超声波指向性强,能量消耗缓慢,在介质中传播的距离较远,因而经常被用于距离的测量。在研究了超声波测距的基本原理的基础上,设计了一套可语音提示的超声波测距系统。包括硬件电路的设计与搭建,以及软件的程序编写,经实物验证,该超声波测距系统硬件设计合理、抗干扰能力较强、语音播报正常、测量精度高。     

一种改进的高精度超声波液位测量方法的研究

超声波测距具有一系列优点,但影响测量精度的因素有很多,因此难以达到较高的精度。在超声波测距原理基础上,针对单超声波换能器温度或温、湿度补偿方案单一,不能在多变、恶劣环境下实现高精度测距的缺陷,以及双超声波换能器标准挡板补偿方案成本高,不能广泛应用在各个领域中的缺陷,设计了借助舵机控制超声波换能器方向的单超声波换能器标准挡板补偿方案。并针对无法精确捕捉第一个回波前沿的要求,提出了使用可编程增益放大器捕获不同距离返回的回波前沿。实验结果表明,在7 m范围内,以空气作为传播介质,反射面为水等具有良好发射性能物质时,测量误差控制在0.4%内,该改进方法能够在恶劣多变环境下实现低成本的高精度测距。     

基于8051单片机的多功能汽车开车控制器

控制器以8051单片机为核心,主要由密码保护、酒精检测及超声波测距防撞等三个了系统模块构成。密码锁系统设定四位十进制数为密码,增强了汽车的防盗性能。酒精检测用气敏传感器检测驾驶者呼气中酒精浓度,可有效防止酒后驾车。超声波测距防撞系统以超声波存空气中传播速度为己知条件,根据发射和接收的时间差计算出发射点到障碍物的实际距离,可预防追尾事件的发生。该控制器克服了传统控制装置功能相对单一、精度低、响应速度慢等缺点,具有广阔的应用前景。     

基于超声波测距的巷道两帮变形量测量系统设计

针对传统的收敛计人工测量法测量矿山巷道变形量费时、费力的缺点,提出基于超声波测距的巷道两帮变形量测量系统设计方案。该系统采用C8051F340单片机控制超声波探头进行超声波的发射和接收,通过温度补偿模块测量实时的环境温度,根据超声波在空气中的传播速度与温度的关系得到实际的超声波速度,并根据超声波测距原理计算巷道两帮的距离。实际测试结果表明,该系统实现了对巷道两帮变形量的实时测量,测量精度为1 mm。     

智能导盲手杖

根据调查显示盲人数量较多,他们因为视力不辨障碍,在日常生活中有着极大的不便和安全隐患,本设计能够有效的探测周围环境并在发出报警信号的同时提醒车辆和行人避让盲人,为盲人出行提供便利。该导盲手杖以STM32F103RCT6处理器为核心处理器、利用超声波在空气中传播的反射原理,以超声波传感器为检测部件,应用超声波在空气中传播的时间差来测量距离,实现了无接触测距、提高了测量精度,并利用GPS模块进行定位并实时位置共享。     

一种基于超声波的检测防撞系统设计

本文提出了一种超声波汽车防撞系统，根据超声波测距原理测出汽车离障碍物距离，应用透射式光电传感器测出汽车速度，应用汇编语言对其软件编程处理，判断是否给出刹车信号。本文给出了超声波防撞系统的设计方法和思路，并根据算法设计了相应的系统电路，软件实现程序。     

基于KL25的高精度无盲区超声波测距系统

在双探头近距离的超声波测距系统中,存在着测量精度不高的问题,并且距离越近误差越大,在测量距离小于10 cm时,由于探头之间的相互影响,将导致无法测量该段距离。本系统根据超声波传播过程中的叠加原理,通过分析探头之间干扰波与从被测物反射的回波的相互叠加,从而消除在近距离测量时的测距盲区。在发射和接收探头之间距离不同时,分析其对测量误差的影响,选择最理想的探头放置距离,并且结合温度对声速传播的影响,设计出近距离高精度无盲区超声波测距系统。     

基于热释电红外传感技术测距的时间差法研究

利用热释电信号幅值法进行目标测距会产生较大的误判,因为输出信号幅值受诸多因素(目标个体差异、穿着服饰、传感器安放位置)的影响。在不附加光学装置或菲尼尔透镜时热释电传感器通常仅能够短距离地感知动目标的存在与否,并不能辨别其出现和距离。使用加装红外透镜的方法将传感器的感知范围延伸至30 m。在对采集到的大量信号进行特征分析后发现模拟信号峰—峰值时间差与动目标距节点间的距离存在线性关系,利用这种关系实现了30 m可探测范围内较高精度的测距。该方法与信号幅值测距法相比,可明显地提高测距的可靠性和准确性。     

基于动态目标位置的智能车辆动态避障控制研究

为了真实地模拟驾驶员在动态环境中避让动态障碍物的行为方式,提出了动态目标位置概念,并采用三次样条曲线作为动态避障的路径拟合曲线。以模糊逻辑为控制策略,以T-S模糊模型为控制结构,以自适应神经网络为隶属度函数的参数调整手段,设计出一种智能车辆横向运动控制器,并通过计算机仿真实现。结果表明,基于动态目标位置概念的控制器设计具有较好的控制性能,较为理想地模拟实际交通环境中车辆动态避障的特性。     

Autonomous Navigation of an Unmanned Air Vehicle Towards a Moving Ship

This paper deals with the problem of autonomous navigation of an unmanned air vehicle towards a moving ship. The ship is moving in the horizontal plane; however, its motion is not a priori known to the air vehicle. The control laws for the flight path angle and the heading angle of the air vehicle are based on the relative kinematics equations between the vehicle and the moving ship. The goal of the control law is to drive the vertical line of sight angle to zero, while the horizontal line of sight angle tracks the heading angle of the ship. This results in a decreasing range in both the horizontal and vertical planes. The kinematics equations under the control law are derived and our results are rigorously proven. Simulation of various scenarios is carried out.     

基于多体动力学理论的赛车游戏引擎的设计与实现

运动车辆的实时建模、动力学行为仿真是赛车虚拟环境中的重要组成部分。论文设计并实现了一实时赛车游戏引擎,在引擎车辆建模中提出了一种基于多体动力学理论实时逼真的赛车建模方法,对赛车的真实受力状况进行简化,模拟车辆的各种动力学行为和车辆运动的真实感绘制。并实现了引擎中的碰撞检测技术、音效处理技术、虚拟环境的实时绘制技术。增强用户漫游虚拟环境的沉浸感。     

简支梁移动质量响应分析

随着行车速度与交通量不断增加,荷载不断加重,桥梁的移动荷载响应越来越得到人们的重视.考虑移动车辆的惯性效应与桥梁的阻尼效应时,需要把车辆荷载简化为移动质量进行研究,这时得到的控制方程是变系数偏微分方程,在数学上通常难以精确求解.经分离变量与模态叠加后,化为变系数常微分方程组.本文利用WKB法,得到了近似的动力学响应,并与数值解、移动常力、Inglis解进行了比较.     

The microfabrication of capacitive ultrasonic transducers

Surface-micromachined capacitive ultrasonic transducers, which are suitable for operation in both air and water, have been fabricated and tested. Amorphous silicon is used as a sacrificial layer because of its good etching selectivity versus a nitride membrane, and improved cell-size control is obtained by lithographic definition of cavity walls. In addition, appropriate feature designs based on two-dimensional (2-D) process simulations make it possible to achieve device cavity sealing with g-line optical lithography. Transmission experiments in both water and air are presented. A dynamic range in excess of 110 dB is observed in air at 2.3 MHz. In water, a single pair of transducers is able to operate from 2 to 15 MHz. When tuned, a 3.5-MHz tone burst results in a received signal with better than 60-dB signal-to-noise ratio (SNR). The transducer behaviour agrees with a theoretical understanding of transducer dynamics. The dynamic ranges achieved in this paper are the best reported to date for surface-micromachined capacitive ultrasonic transducers     

Multi-objective model-based control for an automotive catalyst

A model-based feedforward/feedback air fuel ratio controller that optimizes the oxygen storage capacity of the three-way catalyst in automotive emission control systems is presented. This work incorporates a simplified dynamic catalyst model that describes the physical behavior of oxygen chemisorption and reversible deactivation in the catalyst system. A novel aspect of this work is the use of the oxygen storage capability of the catalyst not only to minimize vehicle emissions but also to optimize engine performance and fuel economy during transient engine demand. The feedback/feedforward controller is a nonlinear model predictive controller that incorporates catalyst, engine air fuel ratio controller, and fuel system models to determine the optimal air fuel ratio target trajectory. Feedback is provided by a nonlinear moving horizon estimation strategy for the determination of the oxygen storage level of the catalyst based on air fuel ratio sensors.     

Model based vehicle detection and tracking for autonomous urban driving

Situational awareness is crucial for autonomous driving in urban environments. This paper describes the moving vehicle detection and tracking module that we developed for our autonomous driving robot Junior. The robot won second place in the Urban Grand Challenge, an autonomous driving race organized by the U.S. Government in 2007. The module provides reliable detection and tracking of moving vehicles from a high-speed moving platform using laser range finders. Our approach models both dynamic and geometric properties of the tracked vehicles and estimates them using a single Bayes filter per vehicle. We present the notion of motion evidence, which allows us to overcome the low signal-to-noise ratio that arises during rapid detection of moving vehicles in noisy urban environments. Furthermore, we show how to build consistent and efficient 2D representations out of 3D range data and how to detect poorly visible black vehicles. Experimental validation includes the most challenging conditions presented at the Urban Grand Challenge as well as other urban settings.