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.     

Reliability analysis and design of a fault-tolerant random access memory system

The design of a modular RAM system which is organized in a number of memory cards is examined. Two important factors are taken into account: the size of the memory chips used in a particular memory design, and the number of memory partitions which gives the maximum memory system reliability. Expressions are derived for three memory designs using two extreme failure models for the memory chips. These provide upper and lower bounds for the card and the entire memory system reliability, and allow the selection of an optimal configuration for a memory system which has a specified capacity and word length with (1) SEC or (2) SED-DED codes with spare memory cards.     

Design of a fault-tolerant IPM motor for electric power steering

This paper deals with the design of an interior permanent magnet (IPM) motor for power steering. Such an application requires an imperative fault-tolerant capability that is obtained by means of a redundant solution with two motors on the same shaft. A ball-screw system converts the rotating movement into the linear movement of the steering rack. In addition, the IPM motor has to exhibit very low braking torque after a short-circuit fault. Useful relationships between the maximum braking torque and the motor parameters are found and used in the design of the motor.     

Controller design and analysis for automatic steering of passenger cars

This paper deals with a lateral controller design for active 2WS vehicles in ITS applications. First, the vehicle dynamics for typical lateral maneuvers are rigorously described by Newton's formulation. Next, based on a linear perturbed model, a robust controller via μ (mu)-synthesis is designed. Due to the characteristics of D–K iteration, the resulting high-order controller has to be reduced for implementation. Then the frequency- and time-domain responses of the robust controller are extensively evaluated through numerical simulations. Further, we present performance comparisons between full-order controller and reduced-order controller. Finally, the automated steering control presented here is shown to be robust to the prescribed levels of uncertainty for highway maneuvers.     

导向矢量失配条件下的参数化检测器的设计与分析

在检测器设计阶段所假定的信号模型与实际信号之间的失配,会导致检测性能的降低。将检测器参数化,通过调节参数值,可以实现检测器对失配信号检测性能的控制。本文将参数化检测器设计方法分为加数因子法、乘数因子法、指数因子法等,给出了不同设计方法获得检测器性能计算方法,并利用计算机仿真,分析了参数化检测器的可调性,信号匹配和失配下的检测性能。研究表明,采用加数因子法的参数化检测器可以获得更为稳健的检测性能,而采用指数因子法的参数化检测器可以获得更为敏感的检测性能。在检测器设计阶段所假定的信号模型与实际信号之间的失配,会导致检测性能的降低。将检测器参数化,通过调节参数值,可以实现检测器对失配信号检测性能的控制。本文将参数化检测器设计方法分为加数因子法、乘数因子法、指数因子法等,给出了不同设计方法获得检测器性能计算方法,并利用计算机仿真,分析了参数化检测器的可调性,信号匹配和失配下的检测性能。研究表明,采用加数因子法的参数化检测器可以获得更为稳健的检测性能,而采用指数因子法的参数化检测器可以获得更为敏感的检测性能。      

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.     

Dynamic performance of automated guideway transit vehicles with dual-axle steering

The lateral dynamic performance of automatically guided dual and single steered axle vehicles is determined using a three-degree-of-freedom nonlinear model. Vehicle acceleration levels and tracking errors are determined for performance during curve entry, station entry, and on straight but randomly irregular guideway references. Independent dual-axle controllers, yaw dual-axle controllers, and zero-sideslip dual-axle controllers are studied in detail. Configurations for dual-axle controllers are developed, which have reduced tracking errors and either comparable or reduced acceleration levels in comparison to single-steered axle vehicles for curve and station entry maneuvers.     

Performance and dependability analysis of fault-tolerant networks

Fault-tolerant networks continue their operation even in the presence of some failures. However, failures of components or subsystems can considerably affect the performance behaviour. This paper illustrates the use of Stochastic Reward Models (SRMs) for evaluating combined performance and dependability of fault-tolerant networks. A SRM is composed of a stochastic process, describing the evolution of the system, and a superimposed reward structure, reflecting different performance levels. To study the overall network behaviour, different network performance/dependability are introduced and discussed. Due to the arising complexity of exact SRMs a complexity reduction approach is proposed. For highly reliable networks an approximation of the model is presented.     

Parametric design and application of steering characteristic curve in control for electric power steering

Electric power steering (EPS) is considered as the future of power assisted steering technology for passenger cars. In this paper the authors study the process of how to design the steering characteristic curve, analyze the steering characteristic curve using the driver’s steering feel, and proposes a power sinusoidal steering curve, which is parametric and can be altered easily in the prototype tests. Furthermore the authors study the detecting process of steering torque sensor in EPS control systems, and distinguish between actual steering torque and an ideal one. Using this way the authors deduce a formula to calculate the reference torque, which is based on the variation of the system loads. Finally, experimental results on certain vehicles have indicated the feasibility of the adjustable parameters and the effectiveness of the deduced formula.     

Modeling and control of steering system of heavy vehicles for automated highway systems

This work presents modeling, analysis, and controller design of the steering subsystem of heavy vehicles as a subsystem of vehicle lateral control system for the automated highway systems. A physical model of the steering subsystem is derived where the hydraulic power assist unit is modeled as a family of static nonlinear boost curves. Based on open-loop frequency tests and analysis of the physical model structure and its dynamical characteristics, a nominal second order linear model of the steering subsystem is obtained. Then, a linear robust loop-shaping controller is designed to provide a good tracking performance of the closed-loop dynamics of the steering subsystem for varying gain cross over frequencies which is a result of the nonlinear characteristics of the hydraulic power assist. The controller has been successfully incorporated as an inner-loop controller into the nested lateral control architecture for autonomous driving and its efficacy has been demonstrated experimentally.     

仿生容错系统的可靠性分析

人工生命科学就是研究生物机体的特征，胚胎电子学介绍了新一代生物灵感容错FPGA系列，适合于人工生命的研究，胚胎电子阵列通过硬件冗余和阵列重构机构获得容错功能，本文论述和分析了根据κ-out-of-m可靠性模型的胚胎电子阵列的重构策略。讨论了行取消和细胞取消两种方案。     

汽车电动助力转向系统的开发与设计

为了进一步提高汽车电动助力转向系统的快速、精确及稳定性控制,本文利用直流电动机为汽车的转向系统提供辅助动力,并通过电子控制单元等相关硬件电路,进行数字信号采集、脉宽调制输出等,然后根据单片机相关指令对电动机进行实时控制,并最终由机械传动装置实现助力转向.本文阐述了电动助力转向系统的工作原理和结构特点,用ARM7 S3C44B0X单片机为控制电路的核心部件,并实现该控制器的硬件和软件设计,实验结果表明该控制系统是有效的.     

Distribution-free analysis of repairable fault-tolerant systems

This paper presents a unified treatment of methods for distribution-free analysis of repairable fault-tolerant systems. Material from diverse sources is presented for the first time in an integrated, easily accessible unit. In addition, new results are derived which enable more detailed analysis than had carlier been possible. New, streamlined proofs based only on elementary techniques are developed, facilitating extensions of the theory to a wider range of applications.     

快速反射镜控制回路设计与仿真

简要介绍了快速反射镜的工作原理,针对存在的问题提出采用优化结构布局的解决方法,理论推导了优化布局后的伺服机构传递函数,并据此传递函数设计了控制回路,提出了宽带宽校正网络的设计原则,为抑制伺服机构的低频振荡模式在回路中串接陷波器加以抑制;通过在控制回路中串接解算网络的方法降低多输入多输出控制系统设计的难度。建立了快速反射镜的系统仿真模型,通过系统仿真验证上述方法的可行性;在理论分析的基础上搭建实验平台,通过对实验平台施加不同的激励信号,对快速反射镜的性能参数进行测试,验证了理论模型的准确性。     

Propulsion system design of electric and hybrid vehicles

There is a growing interest in electric and hybrid-electric vehicles due to environmental concerns. Efforts are directed toward developing an improved propulsion system for electric and hybrid-electric vehicles applications. This paper is aimed at developing the system design philosophies of electric and hybrid vehicle propulsion systems. The vehicles' dynamics are studied in an attempt to find an optimal torque-speed profile for the electric propulsion system. This study reveals that the vehicles' operational constraints, such as initial acceleration and grade, can be met with minimum power rating if the power train can be operated mostly in the constant power region. Several examples are presented to demonstrate the importance of the constant power operation. Operation of several candidate motors in the constant power region are also examined. Their behaviors are compared and conclusions are made     

Reliability analysis of real-time fault-tolerant task models

One notable advantage of Model-Driven Architecture (MDA) method is that software developers could do sufficient analysis and tests on software models in the design phase, which helps construct high confidence on the expected software behaviors and performance, especially for safety-critical real-time software. Most existing literature of reliability analysis ignores the effects from those deadline requirements of tasks which are critical properties for real-time software and thus cannot be ignored. Considering the contradictory relationship between the deadline requirements and time costs of fault tolerance in real-time tasks, in this paper, we present a novel reliability model, which takes schedulability as one of the major factors affecting the reliability, to analyze reliability of the task execution model in real-time software design phase. The tasks in this reliability model has no restrictions on their distributions and thus could be distributed on a multiprocessor or on a distributed system. Furthermore, the tasks also define arrival rates of faults and fault-tolerant mechanisms to model the occurrences of non-permanent faults and the corresponding time costs of fault handling. By analyzing the probability of tasks still being schedulable in the worst-case execution scenario with faults occurring, reliability and schedulability are combined into an unified analysis framework, and two algorithms for reliability analysis are given. To make this reliability model more pragmatic, we also present an estimation technique for estimating the fault arrival rate of each task. We show through two case studies respectively the detailed derivation process under static-priority scheduling in a multiprocessor system and in the design process of avionics software, and then analyze the factors affecting the reliability analysis by setting up simulation experiments. When no assumptions of fault occurrences made on the task model, this reliability model regresses to a generic schedulability model.     

Mechatronic design and control of hybrid electric vehicles

The work in this paper presents techniques for design, development, and control of hybrid electric vehicles (HEV). Toward these ends, four issues are explored. First, the development of HEV is presented. This synopsis includes a novel definition of degree of hybridization for automotive vehicles. Second, a load-leveling vehicle operation strategy is developed. In order to accomplish the strategy, a fuzzy logic controller is proposed. Fuzzy logic control is chosen because of the need for a controller for a nonlinear, multidomain, and time-varying plant with multiple uncertainties. Third, a novel technique for system integration and component sizing is presented. Fourth, the system design and control strategy is both simulated and then implemented in an actual vehicle. The controller examined in this study increased the fuel economy of a conventional full-sized vehicle from 40 to 55.7 mi/h and increased the average efficiency over the Federal Urban Driving Schedule from 23% to 35.4%. The paper concludes with a discussion of the implications of intelligent control and mechatronic systems as they apply to automobiles     

A unique fault-tolerant design for flying capacitor multilevel inverter

This paper presents a unique design for flying capacitor type multilevel inverters with fault-tolerant features. When a single-switch fault per phase occurs, the new design can still provide the same number of converting levels by shorting the fault power semiconductors and reconfiguring the gate controls. The most attractive point of the proposed design is that it can undertake the single-switch fault per phase without sacrificing power converting quality. Future more, if multiple faults occur in different phases and each phase have only one fault switch, the proposed design can still conditionally provide consistent voltage converting levels. This paper will also discuss the capacitor balancing approach under fault-conditions, which is an essential part of controlling flying capacitor type multilevel inverters. Suggested fault diagnosing methods are also discussed in this paper. Computer simulation and lab results validate the proposed controls.     

某飞行器舵机控制系统硬件设计

研究一种基于TMS320F28335 DSP(Digital Signal Processor)的全数字飞行器控制系统的硬件设计,分析了其结构组成:主控制器电路、舵面位置检测电路和通讯等硬件电路设计。经过多次试验调试,所设计的硬件系统可以满足飞行器性能要求。     

Optimal design of fault-tolerant distributed systems based on arecursive algorithm

The authors address the issue of optimal design (in terms of the number of processors) of a distributed system which is based on a recursive algorithm for fault tolerance (RAFT). The reliability and performance of the system using RAFT are determined as a function of reliability of individual processors and the number of fault modes in a processor. Also discussed are how to determine the design policies when the objective is to minimize the average system failure. Several numerical examples illustrate the results