Resilient and Safe Platooning Control of Connected Automated Vehicles Against Intermittent Denial-of-Service Attacks

Connected automated vehicles (CAVs) serve as a promising enabler for future intelligent transportation systems because of their capabilities in improving traffic efficiency and driving safety, and reducing fuel consumption and vehicle emissions. A fundamental issue in CAVs is platooning control that empowers a convoy of CAVs to be cooperatively maneuvered with desired longitudinal spacings and identical velocities on roads. This paper addresses the issue of resilient and safe platooning control of CAVs subject to intermittent denial-of-service (DoS) attacks that disrupt vehicle-to-vehicle communications. First, a heterogeneous and uncertain vehicle longitudinal dynamic model is presented to accommodate a variety of uncertainties, including diverse vehicle masses and engine inertial delays, unknown and nonlinear resistance forces, and a dynamic platoon leader. Then, a resilient and safe distributed longitudinal platooning control law is constructed with an aim to preserve simultaneous individual vehicle stability, attack resilience, platoon safety and scalability. Furthermore, a numerically efficient offline design algorithm for determining the desired platoon control law is developed, under which the platoon resilience against DoS attacks can be maximized but the anticipated stability, safety and scalability requirements remain preserved. Finally, extensive numerical experiments are provided to substantiate the efficacy of the proposed platooning method.      

Dynamic Event-Triggered Scheduling and Platooning Control Co-Design for Automated Vehicles Over Vehicular Ad-Hoc Networks

This paper deals with the co-design problem of event-triggered communication scheduling and platooning control over vehicular ad-hoc networks (VANETs) subject to finite communication resource. First, a unified model is presented to describe the coordinated platoon behavior of leader-follower vehicles in the simultaneous presence of unknown external disturbances and an unknown leader control input. Under such a platoon model, the central aim is to achieve robust platoon formation tracking with desired inter-vehicle spacing and same velocities and accelerations guided by the leader, while attaining improved communication efficiency. Toward this aim, a novel bandwidth-aware dynamic event-triggered scheduling mechanism is developed. One salient feature of the scheduling mechanism is that the threshold parameter in the triggering law is dynamically adjusted over time based on both vehicular state variations and bandwidth status. Then, a sufficient condition for platoon control system stability and performance analysis as well as a co-design criterion of the admissible event-triggered platooning control law and the desired scheduling mechanism are derived. Finally, simulation results are provided to substantiate the effectiveness and merits of the proposed co-design approach for guaranteeing a trade-off between robust platooning control performance and communication efficiency.      

Wheeled Mobile Robots Control in a Linear Platoon

Future transportation systems will require a number of drastic measures, mostly to lower traffic jams and air pollution in urban areas. Automatically guided vehicles capable of driving in a platoon fashion will represent an important feature of such systems. Platooning of a group of automated wheeled mobile robots relying on relative sensor information only is addressed in this paper. Each vehicle in the platoon must precisely follow the path of the vehicle in front of it and maintain the desired safety distance to that same vehicle. Vehicles have only distance and azimuth information to the preceding vehicle where no inter-vehicle communication is available. Following vehicles determine their reference positions and orientations based on estimated paths of the vehicles in front of them. Vehicles in the platoon are then controlled to follow the estimated trajectories. Then presented platooning control strategies are experimentally validated by experiments on a group of small-sized mobile robots and on a Pioneer 3AT mobile robot. The results and robustness analysis show the proposed platooning approach applicability.     

A centralized control system for ecological vehicle platooning using linear quadratic regulator theory

This paper presents an ecological vehicle platooning control system that aims in reducing overall fuel consumption of the vehicles in a platoon. A centralized linear quadratic regulator system for controlling the vehicles in the platoon has been developed considering the aerodynamic characteristics of the vehicle and the resistance due to the road slope. The proposed control system is simulated on a highway with up?Cdown slopes for high speed driving. Its fuel saving performance is compared with a conventional decentralized vehicle platooning control system. Computer simulation results reveal the significant improvement in fuel economy by the proposed control system.     

A control strategy for platoons of differential drive wheeled mobile robot

The strategy for the control of vehicle platooning is proposed and tested on different mobile robot platforms. The decentralized platooning is considered, i.e. a virtual train of vehicles where each vehicle is autonomous and decides on its motion based on its own perceptions. The following vehicle only has information about its distance and azimuth to the leading vehicle. Its position is determined using odometry. The reference position and the orientation of the following vehicle are determined by the estimated path of the leading vehicle in a parametric polynomial form. The parameters of the polynomials are determined using the least-squares method. This parametric reference path is also used to determine the feed-forward part and to suppress tracking errors by a feed-back part of the applied globally stable nonlinear control law. The results of the experiment and simulations demonstrate the applicability of the proposed algorithm for vehicle platoons.     

Data-iteration cooperative adaptive cruise control of mixed heterogeneous vehicle platoons with unknown dynamic characteristics

This paper considers the cooperative adaptive cruise control (CACC) problem of mixed heterogeneous vehicle platoons composed of human-driven and CACC vehicles with unknown dynamic characteristics and an alternative to CACC for platooning of the heterogeneous vehicle platoon is presented. Adaptive dynamic programming is firstly used to learn the dynamic characteristics of acceleration of vehicles from the sampled data. Then the data-iteration optimal CACC controller is computed to ensure that each CACC vehicle can reach a desired inter-vehicle distance and desired common velocity with no prior knowledge of the dynamics of vehicles in the mixed platoon. Moreover, the string stability of the mixed vehicle platoon is derived by establishing some sufficient conditions on the acceleration transfer function of adjacent vehicles. Two simulation experiments of a six-vehicle mixed platoon are used to illustrate the effectiveness of the proposed CACC method.     

Experimental evaluation of decentralized cooperative cruise control for heavy-duty vehicle platooning

In this paper, we consider the problem of finding decentralized controllers for heavy-duty vehicle (HDV) platooning by establishing empiric results for a qualitative verification of a control design methodology. We present a linear quadratic control framework for the design of a high-level cooperative platooning controller suitable for modern HDVs. A nonlinear low-level dynamical model is utilized, where realistic response delays in certain modes of operation are considered. The controller performance is evaluated through numerical and experimental studies. It is concluded that the proposed controller behaves well in the sense that experiments show that it allows for short time headways to achieve fuel efficiency, without compromising safety. Simulation results indicate that the model mimics real life behavior. Experiment results show that the dynamic behavior of the platooning vehicles depends strongly on the gear switching logic, which is confirmed by the simulation model. Both simulation and experiment results show that the third vehicle never displays a bigger undershoot than its preceding vehicle. The spacing errors stay bounded within 6.8 m in the simulation results and 7.2 m in the experiment results for varying transient responses. Furthermore, a minimum spacing of −0.6 m and −1.9 m during braking is observed in simulations and experiments, respectively. The results indicate that HDV platooning can be conducted at close spacings with standardized sensors and control units that are already present on commercial HDVs today.     

交通信息物理系统中的车辆协同运行优化调度

运输成本及温室气体的排放是衡量智能交通系统的重要指标，有效的运输调度可以降低运输成本和环境损害.针对路网中集成环保型货车的运输问题，本文提出一种基于交通信息物理系统（Transportation cyber physical system，TCPS）的大规模车辆协同调度及合并方案，以最大限度地降低运输成本和碳排放量.首先，采用局部调度策略，结合领队车辆选择算法及聚类分析，构建可合并车辆集合；然后，通过数学规划方法，实现每个车队集合中车辆路径与速度的改进优化处理；最后，通过突发情况的简易处理说明本文调度策略的可扩展性.仿真实验表明，用本文方法将车辆编组合并成车队行驶，较固定路径合并策略可显著降低路网中货运车辆的整体油耗.     

空气流动阻力下非线性车辆队列最优能耗控制方法

为了优化车辆队列在长距离行驶过程中的能源消耗,对空气流动阻力下车辆队列能耗优化间距策略以及相应的队列控制方法进行了研究;首先根据车辆队列在行驶过程中受到的空气流动阻力,建立基于异构风阻系数的车辆动力学模型;其次,设计基于滑模控制的非线性车辆队列控制方法,使其能够在不同风阻系数下稳定地收敛到期望的车辆队列;在此基础上,构建稳态下车辆队列能量消耗评价模型,并通过优化分析,计算能量消耗最优下的车辆队列期望车间距;最后通过数值仿真的手段验证所提控制方法的有效性与可行性;该结果表明:所设计的控制器能够使整个车辆队列达到期望的控制效果;得到的最优车间距能够使得特定条件下车辆队列稳态能量消耗降低。     

Pushing the limits: From lanekeeping to autonomous racing

The success of Electronic Stability Control (ESC) has demonstrated the potential life-saving benefits of vehicle control systems. Lanekeeping presents an obvious next step in vehicle control, but the performance of such systems must be guaranteed before lanekeeping can be viewed as a safety feature. This paper demonstrates that simple lookahead control schemes for lanekeeping are provably robust even at the limits of tire adhesion. By responding to the heading error relative to the desired path, these schemes provide the countersteer behavior necessary to compensate for rear tire saturation and stabilize the vehicle. Using a Lyapunov-based analysis, vehicle stability can be proven even with a highly saturated tire. Taking this a step further by developing a desired path based on the racing line, this lookahead controller can be coupled with longitudinal control based on path position and wheel slip to create an autonomous racecar. The performance of this algorithm shows the potential for lanekeeping control that can truly assist even the best drivers.     

From vehicular platoons to general networked systems: String stability and related concepts

Networked systems and their control are highly important and appear in a variety of applications, including vehicle platooning and formation control. Especially vehicle platoons have been intensively investigated. An interesting problem that arises in this area is string stability, which broadly speaking means that an input signal amplifies unboundedly as it travels through the vehicle string. However, various, not necessarily equivalent, definitions are commonly used. In this paper, we aim to formalise the notion of string stability and illustrate the importance of those distinctions on simulation examples. A second goal is to extend the definitions to general networked systems.     

Experimental Verification of a Drift Controller for Autonomous Vehicle Tracking: a Circular Trajectory Using LQR Method

This study develops an autonomous vehicle control method that enables it to perform a drift maneuver which is an expert driving technique consisting of sliding the rear wheel intentionally for fast cornering. By developing an autonomous control algorithm for such an agile maneuver, the safety of the future autonomous vehicle on extreme conditions such as slippery road, will be increased. Drift equilibrium states are derived to find the suitable feedforward control input for the scale car to enter the drifting region. In addition, a feedback controller is designed based on the linear quadratic regulator method in order to track the circular trajectory and maintain drift equilibrium states. To validate the performance of the developed control algorithm a 1:10 scale car experimental platform is developed with on-board control and sensor system. The feasibility of the developed method for the autonomous vehicle is confirmed through both simulation and experiments following circular trajectories while maintaining the desired equilibrium states.

     

过渡目标值的非线性PID对自治水下机器人变深运动的稳定控制

针对传统PID在控制自治水下机器人(autonomous underwater vehicle,AUV)变深运动时易出现超调、大幅波动等问题,提出一种具有过渡目标值过程来调节误差反馈的非线性PID控制器.在分析传统PID控制下系统出现超调原因的基础上,对系统目标值安排过渡过程,利用系统输出跟踪过渡后的目标值进行误差反馈控制.通过赫尔维兹判据证明了系统稳定性,仿真验证了控制的可行性.最后通过湖上试验验证其工程可行性与实用性,得出在非线性过渡目标值的PID控制下,系统的动态响应特性得以优化,变深超调和波动问题明显改善,可实现AUV平稳地变深运动控制.     

Lane-keeping assistance control algorithm using differential braking to prevent unintended lane departures

This paper describes a hierarchical lane keeping assistance control algorithm for a vehicle. The proposed control strategy consists of a supervisor, an upper-level controller and a lower-level controller. The supervisor determines whether lane departure is intended or not, and whether the proposed algorithm is activated or not. To detect driver′s lane change intention, the steering behavior index has been developed incorporating vehicle speed and road curvature. To validate the detection performance on the lane change intention, full-scale simulator tests on a virtual test track (VTT) are conducted under various driving situations. The upper-level controller is designed to compute the desired yaw rate for the lane departure prevention, and for the guidance with ride comfort. The lower-level controller is designed to compute the desired yaw moment in order to track the desired yaw rate, and to distribute it into each tire′s braking force in order to track the desired yaw moment. The control allocation method is adopted to distribute braking forces under the actuator’s control input limitation. The proposed lane keeping assistance control algorithm is evaluated with human driver model-in-the-loop simulation and experiments on a real vehicle.     

基于滑模自抗扰的智能车路径跟踪控制

针对传统的基于精确数学模型的路径跟踪控制方法很难适应复杂多变驾驶环境的问题,提出一种基于终端滑模控制与自抗扰控制的路径跟踪控制方法.首先,通过构造一个期望偏航角函数能够满足当车辆的实际偏航角趋近于该期望偏航角时其侧向位移偏差趋近于零,从而简化路径跟踪控制;然后,采用扩张状态观测器实时估计系统的未建模动态,同时采用非奇异终端滑模来设计非线性误差反馈律,从而实现偏航角快速、准确地跟踪控制.仿真结果表明,所设计的控制器能够保证车辆稳定行驶的同时快速、精确地跟踪期望的路径.     

Fuel efficiency‐oriented platooning control of connected nonlinear vehicles: A distributed economic MPC approach

This paper considers the fuel efficiency‐oriented platooning control problem of connected vehicles. We present a novel distributed economic model predictive control (EMPC) approach to solve the problem of the vehicle platoon subject to nonlinear dynamics and safety constraints. In order to improve fuel economy of the whole vehicle platoon, the fuel consumption criterion is used to design the distributed EMPC strategy for the platoon. Meanwhile, the car‐tracking performance is exploited to guarantee stability and string stability of the platoon. Then the fuel efficiency control problem of the platoon is formulated as a distributed dual‐layer economic optimal control problem, which is solved in a fashion of receding horizon. It is proved that the proposed strategy guarantees asymptotic stability and predecessor‐follower string stability as well as fuel economy of the whole platoon by minimizing the fuel consumption cost. Finally, the effectiveness of the proposed strategy is highlighted by comparing its performance with that of the traditional distributed MPC strategy in numerical simulations.     

Collision-free control of an omni-directional vehicle

This study addresses the problem of controlling an omni-directional vehicle with both state and control dependent constraints. The task of the vehicle is to attain its desired final position given in the task space. The control constraints resulting from the physical abilities of actuators driving the vehicle wheels are also taken into account during the robot movement. The problem of collision avoidance is solved here based on an exterior penalty function approach which results in smooth vehicle velocities near obstacles. Provided that, a solution to the aforementioned vehicle task exists, the Lyapunov stability theory is used to derive the control scheme. The numerical simulation results carried out for the omni-directional vehicle operating in both a constraint-free task space and task space including obstacles, illustrate the performance of the proposed controllers.     

基于驾驶状态预测的人机力矩协同转向控制器设计

针对人机协同转向控制中对于驾驶员参与和驾驶员状态考虑较少这一问题,提出一种基于驾驶员状态预测的人机力矩协同(human-vehicle torque collaborative based on driver state prediction,HVTC-DSP)转向控制方法.该方法以力矩为人机交互接口,提高了驾驶员的参与程度;同时,在控制器设计过程中采用模型预测控制方法,将驾驶员状态考虑在内,对驾驶员状态进行预测.采用高精度车辆仿真软件veDYNA进行仿真验证,结果表明,与不考虑驾驶员状态的人机协同力矩(human-vehicle torque collaborative based on no driver state prediction,HVTC-NDSP)转向控制方法相比,所提方法可以使辅助力矩更好地跟随驾驶员动作,提高车辆转向性能,减小侧向位移偏差,同时对不同驾驶员也有较好的适应性.进而,以驾驶员下一步动作为参考,使驾驶员当前力矩尽可能接近下一步期望的力矩,在转向性能几乎不受影响的情况下,适当减轻驾驶员操作负担.     

基于嵌入式控制系统的视觉导引自动小车设计

以嵌入式系统为核心控制器,设计了基于视觉导引的自动小车系统。采用模块化硬件设计,分别开发了运动控制、步进电机移载、视觉导引、自动充电、安全避障、无线通信等各种硬件模块。研究了基于视觉的路径特征提取与识别,设计了分区导引控制算法实现小车自动循迹前进。在Linux操作系统环境下开发了控制系统软件和远程监控软件,最后完成了系统测试与调试。     

基于约束H∞输出反馈的四轮转向模型跟踪控制

以跟踪参考模型为控制策略,提出一种基于约束H_∞输出反馈控制的四轮转向（4WS）控制新方法．将前馈控制和反馈控制相结合,同时控制前、后轮转角,以实现实际车辆模型对参考模型的期望性能跟踪．兼顾抗干扰能力与执行机构输出饱和,将约束H_∞输出反馈控制应用于反馈控制器的设计．仿真实验表明所设计的4WS车辆系统可以很好地跟踪参考车辆模型,提高了车辆的操纵稳定性．