Fault-tolerant control for automated highway systems

Increasing highway traffic congestion and real estate costs that limit the building of new highways has brought about a renewed interest in an automated highway system (AHS) where the vehicle steering task (“lateral control”) and the braking/throttle tasks (“longitudinal control”) are taken over by computers to increase the throughput of existing highways. Since safety plays a key role in the development of an AHS, fault-tolerant control is vital. In this paper, we develop a robust longitudinal sliding-mode control algorithm and prove that this control algorithm is stable for a certain class of faults. In addition, we show that intervehicle spacing errors will not become amplified along the AHS in the event of a loss of lead vehicle information. The performance of the sliding-mode controller is demonstrated through a series of simulations incorporating various vehicle and AHS faults     

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.     

Design and experimental research of observer-based adaptive type-2 fuzzy steering control for automated vehicles with prescribed performance

Steer-by-Wire (SbW) system is a significant electromechanical subsystem of automated vehicles. This paper proposes an observer-based type-2 fuzzy control method for the SbW system with uncertain nonlinearity, unknown modeling parameters, and unavailable state. First, an interval type-2 fuzzy logic system (IT2 FLS) and an IT2 FLS-based state observer are constructed to estimate the uncertain nonlinearity and unavailable state of SbW systems. Then, a prescribed performance control (PPC) method is proposed to achieve the prescribed tracking performance of SbW systems. Much importantly, a modified performance function is incorporated in this control method, such that the prescribed tracking performance can be guaranteed within a finite time regardless of the initial state. Finally, simulation and vehicle experiments are given to verify the effectiveness and superiority of the proposed methods.     

Modeling and deadlock control of automated guided vehicle systems

This paper presents a colored resource-oriented Petri net (CROPN) modeling method to deal with conflict and deadlock arising in automated guided vehicles (AGV) systems. It can handle both bidirectional and unidirectional paths. The former offer additional flexibility, efficiency, and cost saving when compared with the latter. Yet, they exhibit more challenging AGV management problems. Unlike jobs that can enter and leave automated manufacturing systems, AGVs always stay in the system. By modeling nodes with places and lanes with transitions, the proposed method can construct CROPN models for changing AGV routes. A control policy suitable for real-time implementation is presented.     

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.     

A control system for automated multiscale measuring systems

Quality inspection of micro systems on wafer scale must cope with conflicting demands: nanometer accuracy and high velocity in a comparatively large workspace. An Automated Multiscale Measuring System (AMMS) combines multiple sensors that operate at specific scales by an intelligent measurement strategy in order to balance speed and accuracy. The AMMS demonstrator is based on a modified Mahr MFU 100 with a position and tilt deflection measurement resolution of 1 nm. In this paper multiscale models of a horizontal axis with an operating range of 200 mm and their application to state linearization and control parameterization of the residual dynamics according to multiscale sensor system characteristics are developed and discussed. Main modeling issues are sliding and submicron presliding friction for model-based compensation and control, reaching from submicron positioning to high-velocity trajectory tracking with desired performance. A new experimental design for the identification of presliding friction parameters and a higher-order friction calculator are presented. Experimental results show the effectiveness of this approach.     

Lane assignment on automated highway systems

The automation of highways as part of the intelligent vehicle highway system (IVHS) program is seen as a way to alleviate congestion on urban highways. This paper discusses the concept of lane assignment in the context of automated highway systems (AHS). Lane assignments represent the scheduling of the path taken by the vehicle once it enters an automated multilane corridor. We discuss the classification of lane assignment strategies into nonpartitioned (totally unconstrained, general, and constant lane) and partitioned (destination monotone, origin monotone, and monotone) strategies. Next, an optimization problem is formulated with the performance criterion being a combination of travel time and manoeuvre costs. Conditions under which the optimal strategy is partitioned, or nearly so, are discussed. We present two algorithms to determine suboptimal partitioned strategies given an optimal nonpartitioned one. A case study of a hypothetical automated highway and the strategies obtained for it under the minimization of total travel time criterion is presented     

High-gain observer-based integral sliding mode tracking control for heavy vehicle electro-hydraulic servo steering systems

The electro-hydraulic servo steering system (EHSSS) is the key element to determine the handling and stability of heavy vehicles. Accurate steering control is challenged due to its complicated structure and a wide range of steering loads. In this paper, an output feedback integral sliding mode control (ISMC) method based on high-gain observer is proposed to solve this issue. First, a new Hurwitz matrix design method is presented for EHSSS with non-chain integrator, in order to prove the convergence of the observer error dynamics. Then, the Lyapunov stability of the observer-based controller is verified. Finally, a test bench is established to experimentally validate the proposed method's effectiveness through multiple test scenarios. The results show the tracking error of the proposed method is significantly smaller than PI and similar to full-state feedback integral sliding mode controller. This paper provides a valuable reference for high-gain observer-based nonlinear control applied to a typical electro-hydraulic servo steering system.     

Model-follower longitudinal control for automated guideway transit vehicles

An approach for the design of longitudinal control systems for automated transit vehicles using the vehicle-follower control concept is presented. It is shown that the spacing policy selected for system operations generates a dynamic model for ideal vehicle response during station keeping. The longitudinal control system should force the actual vehicle response to be as close to this model response as possible. Two model-following controller designs are discussed. In one design the command from the controller is acceleration, and in the other design the command from the controller is jerk. The acceleration- and jerk-limited dynamic response of both controllers is examined by the use of describing functions and by computer simulations.     

High-gain observer-based pump/valve combined control for heavy vehicle electro-hydraulic servo steering system

Electro-hydraulic servo steering system (EHSSS) has been widely used in multi-axle heavy vehicles. Noteworthy, the traditional EHSSS controlled only by servo solenoid valve has amounts of energy loss in throttling orifice. Although the steering control accuracy is ensured, it leads to low energy efficiency. In this paper, a novel pump/valve combined control (PVCC) EHSSS is proposed to increase the energy efficiency, which only uses one servo motor pump and one servo solenoid valve to drive the steering trapezoid mechanism. Based on the control objectives of low pressure difference in valve orifice and high steering tracking performance, a dual-input-dual-output control strategy is proposed. To guarantee the high steering tracking performance of PVCC steering system, a high-gain observer based sliding mode controller (HGO-SMC) is designed for controlling the spool displacement of servo solenoid valve. During the steering process, the servo motor pump is controlled by a simple speed feedforward and PID controller, so that the pressure difference in throttling orifice is kept at a low value to reduce the energy wasted. The experimental comparison results show that the proposed method can achieve the same tracking performance as valve control EHSSS with less energy consumption.     

Control design of an automated highway system

Describes the design of an automated highway system (AHS) developed over the past ten years in the California PATH program. The AHS is a large, complex system, in which vehicles are automatically controlled. The design and implementation of the AHS required advances in actuator and sensor technologies, as well as the design, analysis, simulation, and testing of large-scale, hierarchical hybrid control systems. The paper focuses on the multilayer AHS control architecture and some questions of implementation. It discusses in detail the design and safety verification of the on-board vehicle control system and the design of the link-layer traffic-flow controller     

Strategies and spacing requirements for lane changing and mergingin automated highway systems

In automated highway systems (AHS) vehicles are expected to operate using their own sensing and control systems by interacting with other vehicles and the infrastructure in a way that guarantees safety, stability, and high capacity. We examine various alternative scenaria for merging and lane changing and we present an algorithm for calculating the minimum safety spacing for lane changing (MSSLC); that is, we calculate the intervehicle spacing that the vehicles should maintain during a merging or lane changing maneuver so that in the case where one of the vehicles executes an emergency braking manuever, the rest of the vehicles have enough time and space to stop without any collision taking place. The calculation of the MSSLCs for merging or lane changing maneuvers is more complicated than the calculation of the minimum safety spacing for a longitudinal vehicle following since, in the former case we have to take into account the particular lane-changing policy of the merging vehicle as well as the effect of combined lateral/longitudinal motion during the lane changing maneuver. The braking profiles of the vehicles involved in an emergency scenario during a lane changing maneuver depends on the particular AHS operational concept, i.e., on the degree of communication between the vehicles and between the vehicles and the infrastructure. We consider six different AHS operational concepts; for each concept we consider possible emergency braking profiles and we investigate the effect of the particular operational concept on the MSSLC     

Advanced electronic control systems for electric vehicles

The characteristics and relative advantages of several types of electric vehicle control systems are discussed. An advanced electronic control system for a separately excited dc motor is described. Performance characteristics of an electric vehicle using this control are discussed and recommendations for future systems are given.     

Active tape steering control system

Lateral tape motion (LTM) in tape drives hinders accurate servo head positioning and can cause damage to the tape. It is one of the major obstacles to developing high density, high performance tape drives. This paper presents the development an active tape steering system to reduce LTM. The paper also shows the use of Robust Bode (RBode) plot, a relatively new technique for designing robust controllers. The RBode plot translates a robust performance criterion into allowable and forbidden regions on the open-loop Bode plot of a compensated SISO system. With the RBode plot robust controllers can be directly synthesized with classical loop shaping.     

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。     

Design and control considerations for automated ground transportation systems

Fundamental system and control problems associated with proposed automated ground transportation concepts are discussed. The problem formulation provides a systematic approach toward the synthesis and techinical evaluation of a large class and future systems employing automatically controlled single-mode or dual-mode vehicles on intracity guideway networks. Important system engineerig problems--common to some degree to all proposed concepts--are defined and the associated control requirements are discussed. Basic performance criteria, the weighted average travel time and relative safety of travel, are formulated. Tradeoffs between important system parameters are identified and their relations to performance and cost are discussed. Analysis of system operation is based upon idealized models in which perfect information and control are assumed. Upper bounds on performance are thus obtained, and the main constraints are identified. The degradation of system performance resulting from random arrivals and departures is thereafter analyzed quantitatively. Finally, control problems arising from the use of short headways are discussed. The objective of the paper is to help develop a systematic approach to the design of automated transportation systems using digital computers and modern electronic communications. It concentrates on the functional system problems of relatively simple networks, which lend themselves to direct analytical approaches and which constitute a point of departure for more complex networks.     

An automated system for PAA control and adjustment

The paper presents a classification of contemporary methods for measurement of PAA characteristics, potentialities of their development and hardware implementation. The emphasis is made on diagnostic of PAA technical state, on determination of amplitude-phase distribution (APD) over the aperture, and on PAA adjustment procedures. The paper considers technical characteristics of automated measurement systems (AMS) and of the relevant equipment. Examples of AMS application for PAA parameter determination are included.     

Steering control of automated vehicles using absolute positioning GPS and magnetic markers

Steering control for passenger cars on automated highways is analyzed. The feasibility of an automatic steering system based on absolute positioning global positioning system (GPS) and a magnetic marker guidance system has been evaluated using computer simulations. State estimation and control algorithm issues are examined for such a control system. By use of GPS and a magnetic marker sensor, an accurate and real-time estimation of the vehicle's lateral displacements with respect to the road can be accomplished. A steering control algorithm based on road curvature preview for achieving good road tracking and providing ride comfort is also presented. The proposed estimation and control system are validated by simulation results.     

Hierarchical control strategies for multi-mode steering system of emergency rescue vehicle

It is difficult for the traditional emergency rescue vehicles (ERVs) to pass through narrow and complicated areas quickly, which leads to the ERVs missing the best time to rescue disasters seriously. How to improve the trafficability and mobility of vehicles effectively in narrow and complex areas has become an urgent technical demand for the ERVs. In this context, this paper proposes a multi-mode steering system to realize four steering modes of the ERVs. A fire rescue prototype vehicle is developed, and its multi-mode steering system is designed in detail. The hierarchical control strategies of the multi-mode steering system consist of the upper controller and the lower controller. The upper controller is responsible for assigning the steering angles of four wheels of the ERVs based on the Ackerman principle. The lower controller is used to control the ERVs to turn four wheels independently based on the electro-hydraulic fractional order PID (FOPID) control strategy, and then the parameters of the FOPID controller are optimized by the adaptive clonal selection algorithm. The multi-mode steering system proposed was tested on the homemade fire rescue prototype vehicle. The numerical simulations and experiments were conducted to verify the effectiveness of the proposed multi-mode steering system.