Safe and sub-optimal CAV platoon longitudinal control protocol accounting for state constraints and uncertain vehicle dynamics

State constraints and uncertain vehicle dynamics severely affect control stability and performance of connected and autonomous vehicle (CAV). To this end, this study puts forward a safe and sub-optimal longitudinal control protocol for CAV platoon with uncertain vehicle dynamics and state constraints. For platoon leader, a second order disturbance observer with L₂ stability is presented to estimate lumped uncertainty coupled in vehicle dynamics. By iteratively utilizing control barrier functions and control Lyapunov function, state constraints and speed trajectory tracking stability condition are encoded into control constraints. Based on disturbance observer and encoded constraints, an extended quadratic programming is established as trajectory control law for platoon leader. For platoon followers, backstepping method and disturbance observer accounting for forward communication network are synthesized as formation control law. Besides, conditions of individual vehicle stability and string stability for formation control law are analyzed. Simulation results show that the leader of platoon can automatically switch its drive mode between speed cruising and safe headway keeping, respectively. Furthermore, each follower in platoon can follow its predecessors coordinatively and precisely.     

Resilient consensus of discrete-time connected vehicle systems with interaction network against cyber-attacks

This paper concerns the consensus of the second-order discrete-time autonomous connected vehicle system (CVS) in presence of cyber-attacks. First, the necessary and sufficient conditions for the autonomous CVS are derived without a cyber-attack. Then, a virtual system in hidden layer, interconnected with the original CVS in platoon layer through the designed interaction network, is introduced to resist cyber attacks. Matrix analysis tool, algebraic graph theory and Lyapunov stability method are used to analyze the convergence of CVS. It is proved that the states of CVS can reach consensus and the state errors converge to a certain bound in the case of attacks existing only in hidden layer, or in the overall system including both hidden layer and platoon layer. Finally, the validity of the proposed control approach is verified by the designed simulations.     

Control of connected vehicles with event-triggered transmission and prescribed energy budget

This paper is concerned with event-triggered cooperative control of a platoon of connected vehicles via vehicular ad hoc networks (VANETs). To reduce communications among vehicles, we introduce a hybrid event-triggered transmission mechanism based on both time elapsed and state error. The effect of time-varying transmission delay and communication energy constraint can be also taken into account in the system modeling and design procedures. The on-board sensors use different power levels to transmit information resulting in different packet loss rates. The vehicular platoon system is proved to be exponentially mean-square stable under the hybrid event-triggering scheme and a constant time headway spacing policy. A framework for co-design of the hybrid event triggering scheme and the output feedback controller is given to guarantee platoon stability and spacing-error convergence along the stream. Numerical simulations are given to demonstrate the effectiveness of proposed method.     

Stochastic synchronization of semi-Markovian jump chaotic Lur’e systems with packet dropouts subject to multiple sampling periods

This paper is concerned with the problem of stochastic synchronization for semi-Markovian jump chaotic Lur’e systems. Firstly, packet dropouts and multiple sampling periods are both considered. By input-delay approach and then fully considering the probability distribution characteristic of packet dropouts in the modeling, the original system is transformed to a stochastic time-delay system. Secondly, by getting the utmost out of the usable information on the actual sampling pattern, the probability distribution values of stochastic delay taking values in m given intervals can be explicitly obtained. Then, a newly augmented Lyapunov-Krasovskii functional is constructed. Based on that, some sufficient conditions in terms of linear matrix inequalities (LMIs) are derived to ensure the stochastic stability of the error system, and thus, the master system stochastically synchronize with the slave system. Finally, the effectiveness and potential of the obtained results is verified by a simulation example.     

基于ADAMS/CAR的某微车操纵稳定性分析

以某微车为研究对象,介绍利用ADAMS/CAR模块建立了该车整车动力学模型的方法,及进行操纵稳定性分析和性能评价的一般步骤。     

嵌入式视频车辆检测系统

设计并实现了一种基于DM642视频车辆检测系统。提出了一种基于虚拟线圈匹配的算法,算法原理是估计车辆的速度和结合背景差统计量来检测通过监测区域的车辆,把算法移植到DM642平台中进行处理运行,处理结果可以满足视频处理的实时性要求,并且算法对外界环境变化的干扰有一定的鲁棒性,准确的车流量检测精度,并且运行稳定。     

Robust gain-scheduled output feedback yaw stability control for in-wheel-motor-driven electric vehicles with external yaw-moment

This paper presents a robust gain-scheduled output feedback yaw stability H_∞ controller design to improve vehicle yaw stability and handling performance for in-wheel-motor-driven electric vehicles. The main control objective is to track the desired yaw references by managing the external yaw moment. Since vehicle lateral states are difficult to obtain, the state feedback controller normally requires vehicle full-state feedback is a critical challenge for vehicle lateral dynamics control. To deal with the challenge, the robust gain-scheduled output feedback controller design only uses measurements from standard sensors in modern cars as feedback signals. Meanwhile, parameter uncertainties in vehicle lateral dynamics such as tire cornering stiffness and vehicle inertial parameters are considered and handled via the norm-bounded uncertainty, and linear parameter-varying polytope vehicle model with finite vertices is established through reducing conservative. The resulting robust gain-scheduled output feedback yaw stability controller is finally designed, and solved in term of a set of linear matrix inequalities. Simulations for single lane and double lane change maneuvers are implemented to verify the effectiveness of developed approach with a high-fidelity, CarSim^®, full-vehicle model. It is confirmed from the results that the proposed controller can effectively preserve vehicle yaw stability and lateral handling performance.     

Robust H∞ dynamic output-feedback control for four-wheel independently actuated electric ground vehicles through integrated AFS/DYC

This paper simultaneously addresses the parameter/state uncertainties, external disturbances, input saturations, and actuator faults in the handling and stability control for four-wheel independently actuated (FWIA) electric ground vehicles (EGVs). Considering the high cost of the available sensors for vehicle lateral velocity measurement, a robust H_∞ dynamic output-feedback controller is designed to control the vehicle motion without using the lateral velocity information. The investigated parameter/state uncertainties include the tire cornering stiffness, vehicle mass, and vehicle longitudinal velocity. The unmodeled terms in the vehicle lateral dynamics model are dealt as the external disturbances. Faults of the active steering system and in-wheel motors can cause dangerous consequences for driving, and are considered in the control design. Input saturation issues for the tire forces can deteriorate the control effects, and are handled by the proposed strategy. Integrated control with active front steering (AFS) and direct yaw moment (DYC) is adopted to control the vehicle yaw rate and sideslip angle simultaneously. Simulation results based on a high-fidelity and full-car model via CarSim-Simulink show the effectiveness of the proposed control approach.     

Integrated tire slip energy dissipation and lateral stability control of distributed drive electric vehicle with mechanical elastic wheel

Stability and energy consumption have always been important issues in electric vehicle research. Excessive slip energy not only aggravates tire wear, but also consumes energy of electric vehicle. In order to ensure the lateral stability and to reduce the slip energy dissipation of the distributed drive electric vehicle (DDEV) equipped with Mechanical Elastic Wheel (MEW), an integrated framework considering both tire slip energy dissipation and lateral stability control is proposed. The SESC (Slip Energy and Stability Control) is a hierarchical control framework for DDEV with MEW. A PID speed tracking controller and an (Integral Terminal Slide Mode) ITSM controller are designed at the upper-level controller. The ITSM controller can improve the lateral stability of the vehicle by obtaining the desired yaw moment. Speed tracking controller can stabilize the speed of the vehicle and obtain the desired longitudinal force. At the lower-level controller, the brush model of the MEW is proposed to express tire slip energy. In order to reduce the error of the vehicle dynamics and the slip energy dissipation, a mixed objective function including a holistic corner controller (HCC) and a minimum tire slip energy characterization is proposed. The proposed control framework is verified by Carsim and Matlab/Simulink under emergency simulation conditions. The simulation results show that the SESC based method can improve the lateral stability of DDEV with MEW effectively, and has better performance compared with fuzzyPID+AD based method. Meanwhile, the SESC achieves less slip energy than conventional torque distribution method.     

轮胎侧偏刚度对车辆操纵稳定性影响的分析

车辆操纵稳定性对控制车辆不足转向和过多转向具有重要的意义,对车辆运动的稳态响应和稳定性都十分重要。轮胎侧偏刚度对车辆操纵稳定有着直接或间接的影响．具有不同特性的车辆将表现出与其相对应的瞬态操纵稳定特性。本文通过前后轮胎侧偏刚度对车辆的操纵稳定性进行简要的分析。     

新能源汽车“双积分”政策影响的阶段性特征——经营与环境双重绩效视角

“双积分”政策目的在于促进新能源汽车产业经营绩效与环境绩效的同步增长。以中国新能源乘用车（整车）上市公司作为研究样本,将“双积分”政策划分为酝酿期（2014—2016年）和实施期（2017—2018年）,从显著性、敏捷性和稳定性3个维度,分析了“双积分”政策影响下新能源车企经营绩效与环境绩效的动态变化特征。结果表明：①“双积分”政策在酝酿期便提前释放出了积极作用,环境绩效增长更显著、更稳定,经营绩效政策响应更敏捷;②“双积分”政策在实施期的积极作用进一步增强,经营绩效增长更显著,环境绩效政策响应更敏捷,增长也更稳定。政策制定者在完善和优化“双积分”政策时要善于利用政策信号释放机制,进一步提高和扩大“双积分”政策的适应性、覆盖面和精准度,把握好政策实施和执行的节奏和力度。     

A yaw stability-guaranteed hierarchical coordination control strategy for four-wheel drive electric vehicles using an unscented Kalman filter

A novel hierarchical coordination control strategy (HCCS) is offered to guarantee the stability of four-wheel drive electric vehicles (4WD-EVs) combining the Unscented Kalman filter (UKF). First, a dynamics model of the 4WD-EVs is established, and the UKF-based estimator of sideslip angle and yaw rate is constructed concurrently. Second, the equivalent cornering stiffness coefficients are jointly estimated to consider the impact of vehicle uncertainty parameters on the estimator design. Afterwards, a HCCS with two-level controller is presented. The sideslip angle and yaw rate are controlled by an adaptive backstepping-based yaw moment controller, and the computational burden is relieved by an improved adaptive neural dynamic surface control technology in the upper-level controller. Simultaneously, the optimal torque distribution controller of hub motors is developed to optimize the adhesion utilization ratio of tire in the lower-level controller. Finally, the proposed HCCS has shown effective improvement in the trajectory tracking capability and yaw stability of the 4WD-EVs under various maneuver conditions compared with the traditional Luenberger observer-based and the federal-cubature Kalman filter-based hierarchical controller.     

Output feedback control of an uncertain input-delayed nonlinear system with bounded control commands

This study focused on controlling a class of nonlinear systems with actuation time delays. We proposed a novel output-feedback controller in which the magnitude of the input commands is saturated and can be adjusted by varying control parameters. In this design, a predictor term is used to compensate for delays in the input, and auxiliary systems are exploited to provide a priori bounded control commands and account for the lack of full-state information. The stability analysis results revealed that uniformly ultimately bounded tracking is guaranteed despite modeling uncertainties and additive time-varying disturbances in the system dynamics. The performance of the controller was evaluated through simulation.     

Robust active suppression for body-freedom flutter of a flying-wing unmanned aerial vehicle

Flying-wing unmanned aerial vehicles have received extensive attention over the past decade because of their excellent aerodynamic and stealth performance. However, the aeroelastic interaction problems among unsteady aerodynamics, flight dynamics, and structural dynamics, such as the body-freedom flutter, are still open. This paper presents the study of a robust control scheme for active body-freedom flutter suppression of a flexible flying-wing unmanned aerial vehicle. The control objective is to expand the boundary of body-freedom flutter and to enhance the control robustness to external unknown disturbance simultaneously. The paper begins with the modeling procedure of a parameter-varying aeroservoelastic plant for the design of control law. Then, it presents how to synthesize a robust controller so as to suppress the flutter instability for a wide flight range of dynamic pressures. Afterwards, the paper shows how to analyze the flutter stability of the closed-loop system and the robustness of the controller, respectively. The numerical results demonstrate that the proposed robust controller can not only expand the flutter boundary of the unmanned aerial vehicle by 30%, but also exhibit the strong robustness to external disturbance.     

基于GT-DRIVE的AT车匹配仿真研究

根据AT车动力学方程,在GT-DRIVE6.1.0环境下建立某B级5AT整车模型,并仿真计算不同变矩器和主减速比下整车动力性、经济性的方法。建模仿真过程不仅为该B级车的选型和匹配提供了依据,对AT车的匹配研究也有借鉴意义。     

Finite mode bond graph representation of vehicle-guideway interaction problems

Classical modal analysis techniques for the prediction of vehicle-guideway dynamics are developed and interpreted with bond graph representations. Bond graphs are shown to allow easy generalization to multiple span guideways incorporating virtually any dynamic boundary conditions at the support locations. In addition, non-linear vehicle models can be used with any vehicle displacement-time history desired. Straightforward formulation procedures are also provided through the bond graph representation.The analysis procedure is demonstrated for a two-span Bernoulli-Euler Guideway with first-order dynamic boundary conditions. The results for a vehicle traveling at different speeds are shown to compare favorably with current literature.     

车辆对不平整路面的随机动压力分析

采用双自由度四分之一车辆模型,以路面不平整和车辆发动机振动为激励,运用随机过程理论分析了车辆对不平整路面的随机动压力,得到了车辆动压系数的概率分布以及最大动压系数与路面不平整度、车速、悬挂质量以及悬挂系统与非悬挂系统特性之间的关系。算例分析表明,引起车辆振动的路面不平整波形的频率范围主要集中在0.04～2.0之间,最大动压系数随路面不平整度、车速、悬挂与非悬挂系统刚度的增大而增大,随着悬挂质量以及悬挂系统阻尼的增大而减少,而轮胎阻尼对车辆动荷载的影响并不显著。     

基于路网的动态配送系统软件开发与设计

配送车辆优化调度问题是物流系统中的一个重要环节,本软件借助VB语言,在分析静态配送的基础上,针对不断变化的市场需求,建立动态的物流配送模型,在生成路网的平台上,通过研究物流配送货物过程中路径、车辆选择的问题,提出对物流配送最优路径的动态选择方案,提高物流配送效率,满足客户需求,更符合实际。     

Fault detection for discrete-time systems with randomly occurring nonlinearity and data missing: A quadrotor vehicle example

This paper concerns the fault detection (FD) problem for a class of discrete-time systems subject to data missing and randomly occurring nonlinearity modeled by two independent Bernoulli distributed random variables. We propose to design a set of fault detection filters, or residual generation systems, corresponding to each of the fault components, to guarantee that each subsystem is mean square stable and satisfies a prescribed disturbance attenuation level. Sufficient conditions are established in the form of linear matrix inequalities (LMIs). System faults can be effectively detected by generating the residues and comparing them with the dynamic fault thresholds. A quadrotor vehicle example with faults on angles and angular rates illustrates and verifies the effectiveness of the proposed algorithm.