Autonomous terrain-following for unmanned air vehicles

This paper presents an integrated guidance and control design scheme for an unmanned air vehicle (UAV), and its flight test results. The paper focuses on the longitudinal control and guidance aspects, with particular emphasis on the terrain-following problem. An introduction to the mission, and the terrain-following problem is given first. Waypoints for climb and descent are defined. Computation of the reference trajectory in the vertical plane is discussed, including a terrain-following (TF) algorithm for real-time calculation of climb/descent points and altitudes. The algorithm is particularly suited for online computation and is therefore useful for autonomous flight. The algorithm computes the height at which the vehicle should fly so that a specified clearance from the underlying terrain is always maintained, while ensuring that the vehicle’s rate of climb and rate of descent constraints are not violated. The output of the terrain-following algorithm is used to construct a smooth reference trajectory for the vehicle to track. The design of a robust controller for altitude tracking and stability augmentation of the vehicle is then presented. The controller uses elevators for pitch control in the inner loop, while the reference pitch commands are generated by the outer altitude control loop. The controller tracks the reference trajectory computed by the terrain-following algorithm. The design of an electromechanical actuator for actuating the control surfaces of the vehicle during flight is also discussed. The entire guidance and control scheme is implemented on an actual experimental vehicle and flight test results are presented and discussed.     

Autonomous parking control for intelligent vehicles based on a novel algorithm

Along with the increasing number of vehicles, parking space becomes narrow gradually, safety parking puts forward higher requirements on the driver's driving technology. How to safely, quickly and accurately park the vehiclo to parking space right? This paper presents an automatic parking scheme based on trajectory planning, which analyzing the mechanical model of the vehicle, establishing vehicle steering model and parking model, coming to the conclusion that it is the turning radius is independent of the vehicle speed at low speed. The Matlab simulation environment verifies the correctness and effectiveness of the proposed algorithm for parking. A class of the automatic parking problem of intelligent vehicles is solved.     

Off-highway vehicles

Industrial, agricultural, and military vehicles are classified as "off-highway vehicles"; the class includes tractors, ore trucks, scrapers, and military tanks. These vehicles have prime movers in the 100-to-1000- and-higher horsepower range, generally have top speeds up to 35 mi/h, and operate from low speed at the traction limit to maximum speed over a wide constant-horsepower range. To date, diesel enghtes with gear-shift and torque-converter transmissions have been used. Now, however, the gas turbine has become attractive because of its low weight and bulk per horsepower, particularly for those vehicles whose performance can be raised with higher power. An electric drive system is well suited to a gas turbine prime mover as a means for utilizing the high turbine speed, for handling the large horsepower, and for distributing power to many wheels. On some special heavy vehicles, dc drive systems, patterned after diesel-electric locomotives, are used. Several ac systems using solid-state converters and induction wheel motors have been built experimentally for military vehicles. When all factors are considered, it appears that the combination of the gas turbine and an ac electric drive will become the heavy off-highway vehicle drive system of the future.     

Electric vehicles

The renewed interest in electric vehicles (EVs) in the wake of the California Air Resources Board mandate that 2% of the vehicles lighter than 3750 lb (1700 kg) sold by each manufacturer in that state in 1998 be zero-emission vehicles is examined. The reasons why replacing an internal combustion vehicle (ICV) with an electrically powered equivalent greatly reduces air pollution, not only where the EV is driven, but over the rest of the map as well are discussed. Three drawbacks that have kept EVs from taking over, despite the fact that they are quieter and more reliable as well as less polluting than their internal combustion counterparts, are discussed. They offer limited range on a simple charge, long recharge time, and higher cost than ICVs. The importance of an appropriate infrastructure is stressed     

Hidden antennas for vehicles

The introduction of new telematics and broadcast systems into vehicles has led to a requirement for multiple antennas that can be hidden from view. This paper commences by presenting the results of simulations to identify the components of a car's structure that influence the radiation pattern of a printed VHF antenna on the rear windscreen. Two dual-band antenna designs are then presented for operation in the 900 and 1800 MHz telephone bands. The first is a planar inverted-F antenna that can be concealed in the bumpers, the second a hybrid structure based on the top-loaded monopole principle and mounted beneath the vehicle's roof.     

Thermionic generator for re-entry vehicles

A novel design of a thermionic generator for use on re-entry vehicles is analyzed analytically and experimentally. Equations are derived for prediction of the output current, output power, and conditions of maximum power for the device. The electrical power output potential of a typical re-entry vehicle is obtained by solving the temperature history of a thin-walled emitter. Given the wall temperature and the work function, the saturated Richardson current is easily obtained. Other parameters needed for predicting output power are obtained from curves in the literature. To simulate re-entry conditions, a test model was built and inserted in either a nitrogen or argon plasma jet. Graphite, thoriated tungsten, tungsten and molybdenum were used for the emitter and collector. Of the materials tested, graphite was the only material that met, to some degree, the qualifications needed for operation of the hypersonic plasma thermionic generator.     

飞行器的红外特性

飞行器红外特性研究对许多工程问题有重要意义。文中讨论了飞行器的三种主要红外辐射源即羽流,热空腔－羽流组合体,蒙皮的红外特性。较具体地讨论了飞机在非加力和加力状态下三种辐射源的辐射特性,包括空间特性和光谱特性。同时提供了实测数据作比较,还讨论了飞行器红外特性计算方法的发展及评估。     

Electrical systems for hybrid vehicles

This paper is a digest of the electrical system section of a report [8] on the feasibility of using a hybrid heat engine/electrical propulsion system as a means of reducing exhaust emissions from street-operated vehicles. The electrical system is composed of an electric traction motor, a generator, control system, and batteries. Batteries are not covered in this paper, but the remainder of the items will be treated here. First, the electrical system parameters or characteristics that have the greatest impact on the total system are considered; next, details of the advantages and disadvantages of various approaches are summarized; and, finally, development efforts are recommended.     

Artificial vision in road vehicles

The last few decades have witnessed the birth and growth of a new sensibility to transportation efficiency. In particular the need for efficient and improved people and goods mobility has pushed researchers to address the problem of intelligent transportation systems. This paper surveys the most advanced approaches to (partial) customization of the road following task, using on-board systems based on artificial vision. The functionalities of lane detection, obstacle detection and pedestrian detection are described and classified, and their possible application in future road vehicles is discussed.     

汽车超载监测系统

为了实时识别各种车型的超载车辆,该系统基于开源计算机视觉库(OpenCV),先根据车辆照片库建立车型分类器,然后使用数字摄像机拍摄进入监控区域的车辆,在视频中使用分类器识别车型,根据所识别得到的车型去查询数据库获得该车型的核载,再通过动态称重技术获得车辆的实际载重,及时判别车辆是否超载。此方法可避免过去使用统一重量衡量不同车型是否超载的弊端,并可同时免线圈测量车速。测试结果表明系统能快速准确地识别出车型。配合动态称重系统,就能实时得出所通过的车辆是否超载,对公路养护和道路交通安全有相当大的实用意义。     

互联网自治的改造实现

本文的自治互联网技术结合互联网现实,通过现有域名体系构造出自主自治的可扩展域名体系和层次结构,并提供自治网络系统内/间的域名解释机制,甚至可以单边行动的方式实现互联网自治的过渡和改造。     

Autonomous intelligent cruise control

Vehicle following and its effects on traffic flow has been an active area of research. Human driving involves reaction times, delays, and human errors that affect traffic flow adversely. One way to eliminate human errors and delays in vehicle following is to replace the human driver with a computer control system and sensors. The purpose of this paper is to develop an autonomous intelligent cruise control (AICC) system for automatic vehicle following, examine its effect on traffic flow, and compare its performance with that of the human driver models. The AICC system developed is not cooperative; i.e., it does not exchange information with other vehicles and yet is not susceptible to oscillations and “slinky” effects. The elimination of the “slinky” effect is achieved by using a safety distance separation rule that is proportional to the vehicle velocity (constant time headway) and by designing the control system appropriately. The performance of the AICC system is found to be superior to that of the human driver models considered. It has a faster and better transient response that leads to a much smoother and faster traffic flow. Computer simulations are used to study the performance of the proposed AICC system and analyze vehicle following in a single lane, without passing, under manual and automatic control. In addition, several emergency situations that include emergency stopping and cut-in cases were simulated. The simulation results demonstrate the effectiveness of the AICC system and its potentially beneficial effects on traffic flow     

Autonomous power expert system

The Autonomous Power Expert (APEX) system has been designed to monitor and diagnose fault conditions that occur within the Space Station Freedom Electrical Power System (SSF/EPS) Testbed. The APEX system is being developed at the NASA Lewis Research Center by the Space Electronics Division (SED) in conjunction with the Space Station Directorate and Power Technology Division (PTD). APEX is designed to interface with SSF/EPS testbed power management controllers to provide enhanced autonomous operation and control capability.

The APEX architecture consists of three components: (1) a rule-based expert system, (2) a testbed data acquisition interface, and (3) a power scheduler interface. Fault detection, fault isolation, justification of probable causes, recommended actions, and incipient fault analysis are the main functions of the expert system component. The data acquisition component requests and receives pertinent parametric values from the EPS testbed and asserts the values into a knowledge base. Power load profile information is obtained from a remote scheduler through the power scheduler interface component.

This paper will discuss the current APEX design and development work. Operation and use of APEX by way of the user interface screens will also be covered.     

Doppler steering system for terrestrial vehicles

A Doppler radar unit has been added to a remotely controlled automobile for automatic control of steering. This Doppler-type unit causes the vehicle to turn toward areas of minimum reflectivity, areas usually smooth with low vegetation. The vehicle with this steering system is shown to avoid all obstacles such as trees, automobiles, and people.     

Intelligent semi-autonomous vehicles in materials handling

An increase in functionality of semi-autonomous vehicles (SAV) through the implementation of intelligent distributed control and smart sensing techniques is presented. In combination with a modular design approach, this facilitates system modification and improvement, combined with faster customisation of the platform. A distributed and reactive behavioural control architecture is used to realise local autonomous navigation capabilities; improved operator interaction; self protection and safer operation. A virtual engineering environment based on a computer-aided-graphics platform is used (1) for modelling the vehicle and the environment in which it can operate; (2) developing pre-emptive learning and training of responses/behaviours, and (3) for evaluation of vehicle functionality as part of an integrated materials handling system.     

汽车内部噪声智能控制系统的设计

噪声主动控制基本思想是由德国物理学家Paul Lueg于1936年发明“电子消声器”时首次提出的。噪声主动控制技术相对传统的被动控制,具有对中、低频段噪声控制效果明显、系统轻巧、实时性强等优点,具有潜在的工程应用价值。     

面向汽车的MIMO OTA测试技术

汽车智能网联是当前交通产业发展的主要方向之一。通过汽车与周围车辆、行人、交通设施、蜂窝网络进行信息交互,提升交通网决策管理智能化水平,改善道路安全与效率。如何定量精确地评估整车通信性能是业界关注的热点问题,然而目前尚缺少成熟的解决方案,特别是面向整车产品。主要研究了基于多探头吸波暗室(multi-probe anechoic chamber,MPAC)的汽车空口测量系统的搭建方法,并针对整车空口测试提出了一种低成本解决方案,可以在信道模拟器数字通路受限的情况下,通过数字变换,成倍拓展测试区域。数字仿真结果表明,基于此方案所构造的测试区域,其空间相关性、时间相关性均满足相关标准要求。     

Are hybrid vehicles worth it?

In this paper, the author describes how, despite superior fuel economy and low emissions, hybrid electric vehicles (HEVs) cost too much at present to make economic sense