Case Studies on an Approach to Multiple Autonomous Vehicle Motion Coordination

This paper conducts a series of case studies on a novel Simultaneous Path and Motion Planning (SiPaMoP) approach [1] to multiple autonomous or Automated Guided Vehicle (AGV) motion coordination in bidirectional networks. The SiPaMoP approach plans collision-free paths for vehicles based on the principle of shortest path by dynamically changing the vehicles’ paths,traveling speeds or waiting times,whichever gives the shortest traveling time. It integrates path planning,collision avoidance and motion planning into a comprehensive model and optimizes the vehicles’ path and motion to minimize the completion time of a set of tasks. Five case studies,i.e.,head-on collision avoidance,catching-up collision avoidance,buffer node generation and collision avoidance,prioritybased motion coordination,and safety distance based planning,are presented. The results demonstrated that the method can effectively plan the path and motion for a team of autonomous vehicles or AGVs,and solve the problems of traffic congestion and collision under various conditions.

Connected Vehicle-Based Traffic Signal Coordination

This study presents a connected vehicles(CVs)-based traffic signal optimization framework for a coordinated arterial corridor.The signal optimization and coordination problem are first formulated in a centralized scheme as a mixed-integer nonlinear program(MINLP).The optimal phase durations and offsets are solved together by minimizing fuel consumption and travel time considering an individual vehicle’s trajectories.Due to the complexity of the model,we decompose the problem into two levels:an intersection level to optimize phase durations using dynamic programming(DP),and a corridor level to optimize the offsets of all intersections.In order to solve the two-level model,a prediction-based solution technique is developed.The proposed models are tested using traffic simulation under various scenarios.Compared with the traditional actuated signal timing and coordination plan,the signal timing plans generated by solving the MINLP and the two-level model can reasonably improve the signal control performance.When considering varies vehicle types under high demand levels,the proposed two-level model reduced the total system cost by 3.8%comparing to baseline actuated plan.MINLP reduced the system cost by 5.9%.It also suggested that coordination scheme was beneficial to corridors with relatively high demand levels.For intersections with major and minor street,coordination conducted for major street had little impacts on the vehicles at the minor street.

Adaptive Coordinated Path Tracking Control Strategy for Autonomous Vehicles with Direct Yaw Moment Control

It is a striking fact that the path tracking accuracy of autonomous vehicles based on active front wheel steering is poor under high-speed and large-curvature conditions.In this study,an adaptive path tracking control strategy that coordinates active front wheel steering and direct yaw moment is proposed based on model predictive control algorithm.The recursive least square method with a forgetting factor is used to identify the rear tire cornering stiffness and update the path tracking system prediction model.To adaptively adjust the priorities of path tracking accuracy and vehicle stability,an adaptive strategy based on fuzzy rules is applied to change the weight coefficients in the cost function.An adaptive control strategy for coordinating active front steering and direct yaw moment is proposed to improve the path tracking accuracy under high-speed and large-curvature conditions.To ensure vehicle stability,the sideslip angle,yaw rate and zero moment methods are used to construct optimization constraints based on the model predictive control frame.It is verified through simulation experiments that the proposed adaptive coordinated control strategy can improve the path tracking accuracy and ensure vehicle stability under high-speed and largecurvature conditions.

Stabilization of coordinated motion for underwater vehicles

This paper presents a coordinating and stabilizing control law for a group of underwater vehicles with unstable dynamics. The coordinating law is derived from a potential that only depends on the relative configuration of the underwater vehicles. Being coordinated,the group behaves like one mechanical system with symmetry,and we focus on stabilizing a family of coordinated motions,called relative equilibria. The stabilizing law is derived using energy shaping to stabilize the relative equilibria which involve each vehicle translating along its longest（unstable） axis without spinning,while maintaining a relative configuration within the group. The proposed control law is physically motivated and avoids the linearization or cancellation of nonlinearities.

A signal coordination algorithm for two adjacent intersections based on approximate dynamic programming

To reduce vehicle emissions in road networks, a new signal coordination algorithm based on approximate dynamic programming （ADP） is developed for two intersections. Taking the Jetta car as an experimental vehicle, field tests are conducted in Changchun Street of Changchun city and vehicle emission factors in complete stop and uniform speed states are collected. Queue lengths and signal light colors of approach lanes are selected as state variables, and green switch plans are selected as decision variables of the system. Then the calculation model of the optimization index during the planning horizon is developed based on the basis function method of the ADP. The temporal-difference algorithm is employed to update the weighting factor vector of the approximate function. Simulations are conducted in Matlab and the results show that the established algorithm outperforms the conventional coordination algorithm in reducing vehicle emissions by 8.2%. Sensitive analysis of the planning horizon length on the evaluation index is also conducted and the statistical results show that the optimal length of the planning horizon is directly proportional to the traffic load.

Rigid-Flexible Coupling Dynamic Analysis of Sub-Launched Vehicle During the Vertical Tube-Exit Stage

During the launching stage,hydrodynamic pressure and adapters' reaction loads can influence the vehicle's rigid motion as well as cause its structural vibration,which is a typical rigid-flexible coupling dynamic problem. This paper presents a 2-D rigid-flexible coupling model to calculate the vehicle's dynamic responses in that period.The vehicle was equivalent to a flexure beam with axial deformation. Hybrid coordinate and modal superposition methods were used to describe its large rigid displacement and small deformation. By the second Lagrange equation,the vehicle centroid's displacements,rotational angle and modal coordinates were chosen as generalized coordinates and then the vehicle 's rigid-flexible coupling dynamic equations were obtained. By numerical simulation,the results of vehicle's motion parameters and transverse internal loads were acquired.The calculation results showed that differences of the vehicle's motion parameters between the rigid-flexible coupling model and the rigid body assumption are noticeable and the peak magnitude of the vehicle's transverse internal loads in the rigid-flexible coupling model is higher remarkably than that in the rigid body assumption.

Combined Control Allocation and Sliding Mode Control in the Dynamic Control of a Vehicle with Eight In-Wheel Motors

An eight wheel independently driving steering（8 WIDBS）electric vehicle is studied in this paper.The vehicle is equipped with eight in-wheel motors and a steer-by-wire system.A hierarchically coordinated vehicle dynamic control（HCVDC）system,including a high-level vehicle motion controller,a control allocation,an inverse tire model and a lower-level slip/slip angle controller,is proposed for the over-actuated vehicle system.The high-level sliding mode vehicle motion controller is designed to produce desired total forces and yaw moment,distributed to longitudinal and lateral forces of each tire by an advanced control allocation method.And the slip controller is designed to use a sliding mode control method to follow the desired slip ratios by manipulating the corresponding in-wheel motor torques.Evaluation of the overall system is accomplished by sine maneuver simulation.Simulation results confirm that the proposed control system can coordinate among the redundant and constrained actuators to achieve the vehicle dynamic control task and improve the vehicle stability.

Optimal Operation of Electric Vehicles and Distributed Generation Resources in Smart Grid Considering Load Management

Technology advancement and the global tendency to use renewable energy in distributed generation units in the distribution network have been proposed as sources of energy supply.Despite the complexity of their protection,as well as the operation of distributed generation resources in the distribution network,factors such as improving reliability,increasing production capacity of the distribution network,stabilizing the voltage of the distribution network,reducing peak clipping losses,as well as economic and environmental considerations,have expanded the influence of distributed generation(DG)resources in the distribution network.The location of DG sources and their capacity are the key factors in the effectiveness of distributed generation in the voltage stability of distribution systems.Nowadays,along with the scattered production sources of electric vehicles with the ability to connect to the network,due to having an energy storage system,they are known as valuable resources that can provide various services to the power system.These vehicles can empower the grid or be used as a storage supply source when parked and connected to the grid.This paper introduces and studies a two-stage planning framework for the concurrent management of many electric vehicles and distributed generation resources with private ownership.In the first stage,the aim is to increase the profit of electric vehicles and distributed generation sources;finally,the purpose is to reduce operating costs.The proposed scheduling framework is tested on a distribution network connected to bus 5 of the RBTS sample network.Besides distributed generation sources and electric vehicles,we integrate time-consistent load management into the system.Due to distributed generation sources such as photovoltaic systems and wind turbines and the studied design in the modeling,we use the Taguchi TOAT algorithm to generate and reduce the scenario to ensure the uncertainty in renewable energy.MATLAB software is used to solve the problem and select the optimal answer.

Adaptive coordinated control of engine speed and battery charging voltage

In this paper, the control problem of auxiliary power unit （APU） for hybrid electric vehicles is investigated. An adaptive controller is provided to achieve the coordinated control between the engine speed and the battery charging voltage. The proposed adaptive coordinated control laws for the throttle angle of the engine and the voltage of the power-converter can guarantee not only the asymptotic tracking performance of the engine speed and the regulation of the battery charging voltage, but also the robust stability of the closed loop system under external load changes. Simulation results are given to verify the performance of the proposed adaptive controller.

Coordinated control method of intersection traffic light in one-way road based on V2X

One-way roads have potential for improving vehicle speed and reducing traffic delay.Suffering from dense road network,most of adjacent intersections’distance on one-way roads becomes relatively close,which makes isolated control of intersections inefficient in this scene.Thus,it is significant to develop coordinated control of multiple intersection signals on the one-way roads.This paper proposes a signal coordination control method that is suitable for one-way arterial roads.This method uses the cooperation technology of the vehicle infrastructure to collect intersection traffic information and share information among the intersections.Adaptive signal control system is adopted for each intersection in the coordination system,and the green light time is adjusted in real time based on the number of vehicles in queue.The offset and clearance time can be calculated according to the real-time traffic volume.The proposed method was verified with simulation results by VISSIM traffic simulation software.The results compared with other methods show that the coordinated control method proposed in this paper can effectively reduce the average delay of vehicles on the arterial roads and improve the traffic efficiency.

Centralized Bi-level Spatial-Temporal Coordination Charging Strategy for Area Electric Vehicles

Increased penetration of electric vehicles(EVs)is expected to impact power system performance in adverse ways,e.g.,overloading,uncertain power quality,and increased voltage fluctuation,particularly at the distribution level.Most EV charging control strategies that have been proposed only benefit the grid or EV users.A centralized EV charging strategy based on bilevel optimization is proposed in this paper with the objectives of deriving benefits for the grid and EV users simultaneously.The proposed strategy involves distributing the EV charging load more beneficially across both spatial and temporal levels.In the spatial problem,the whole fleet of EVs is controlled to minimize load variance as spatial coordination,with total charging rate and energy needed as the constraint.While in the temporal problem,EVs in each aggregator are controlled to minimize the charging cost or maximize the EV user’s degree of satisfaction with each aggregator’s charging rate and energy needed as the constraint.The proposed bi-level charging strategy is transformed to a single-stage optimization problem and solved using the classical optimization method.The impacts of uncontrolled charging on the grid and EV users are studied using the Monte Carlo Simulation(MCS)method.Then,the effectiveness of the proposed charging strategy is demonstrated via results obtained in the MCS.

Review on Optimization of Forecasting and Coordination Strategies for Electric Vehicle Charging

The rapid development of electric vehicles(EVs)has benefited from the fact that more and more countries or regions have begun to attach importance to clean energy and environmental protection.This paper focuses on the optimization of EV charging,which cannot be ignored in the rapid development of EVs.The increase in the penetration of EVs will generate new electrical loads during the charging process,which will bring new challenges to local power systems.Moreover,the uncoordinated charging of EVs may increase the peak-to-valley difference in the load,aggravate harmonic distortions,and affect auxiliary services.To stabilize the operations of power grids,many studies have been carried out to optimize EV charging.This paper reviews these studies from two aspects:EV charging forecasting and coordinated EV charging strategies.Comparative analyses are carried out to identify the advantages and disadvantages of different methods or models.At the end of this paper,recommendations are given to address the challenges of EV charging and associated charging strategies.

Coordinated Control Architecture for Motion Management in ADAS Systems

Advanced driver assistance systems(ADAS) seek to provide drivers and passengers of automotive vehicles increased safety and comfort. Original equipment manufacturers are integrating and developing systems for distance keeping, lane keeping and changing and other functionalities. The modern automobile is a complex system of systems. How the functionalities of advanced driver assistance are implemented and coordinated across the systems of the vehicle is generally not made available to the wider research community by the developers and manufactures. This paper seeks to begin filling this gap by assembling open source physics models of the vehicle dynamics and ADAS command models. Additionally, in order to facilitate ADAS development and testing without having access to the details of ADAS, a coordinated control architecture for motion management is also proposed for distributing ADAS motion control commands over vehicle systems. The architecture is demonstrated in a case study where motion is coordinated between the steering and the braking systems, which are typically used only for a single functionality. The integrated vehicle and system dynamics using the coordinated control architecture are simulated for various driving tasks. It is seen that improved trajectory following can be achieved by the proposed coordinated control architecture. The models, simulations and control architecture are made available for open access.

Bi-level ramp merging coordination for dense mixed traffic conditions

Connected and Autonomous Vehicles(CAVs)hold great potential to improve traffic efficiency,emissions and safety in freeway on-ramp bottlenecks through coordination between mainstream and on-ramp vehicles.This study proposes a bi-level coordination strategy for freeway on-ramp merging of mixed traffic consisting of CAVs and human-driven vehicles(HDVs)to optimize the overall traffic efficiency and safety in congested traffic scenarios at the traffic flow level instead of platoon levels.The macro level employs an optimization model based on fundamental diagrams and shock wave theories to make optimal coordination decisions,including optimal minimum merging platoon size to trigger merging coordination and optimal coordination speed,based on macroscopic traffic state in mainline and ramp(i.e.,traffic volume and penetration rates of CAVs).Furthermore,the micro level determines the real platoon size in each merging cycle as per random arrival patterns and designs the coordinated trajectories of the mainline facilitating vehicle and ramp platoon.A receding horizon scheme is implemented to accommodate human drivers’stochastics as well.The developed bi-level strategy is tested in terms of improving efficiency and safety in a simulation-based case study under various traffic volumes and CAV penetration rates.The results show the proposed coordination addresses the uncertainties in mixed traffic as expected and substantially improves ramp merging operation in terms of merging efficiency and traffic robustness,and reducing collision risk and emissions,especially under high traffic volume conditions.

Robust Coordinated Control for a Type of Hypersonic Aircraft

We investigate couplings between variables of attitude dynamics for a hypersonic aircraft,and present a nonlinear robust coordinated control scheme for it.First,we design three kinds of coordinated factors to restrain the strong couplings.Then,we use projection mapping to estimate the uncertain nonlinear functions of the aircraft.Combining the coordinated factors and the designed control laws,we obtain a coordinated torque and assign it to the control deflection commands by using the allocation matrix.A stability analysis demonstrates that all the signals of the closed-loop system are uniformly and fully bounded.Finally,the robust coordinated performance of the designed scheme is verified through numerical simulations.

考虑电动汽车充放电的输配协同能量-灵活性市场出清机制

为应对输电网对灵活性资源的迫切需求,挖掘配电网分布式资源的灵活性支撑潜力,首先,构建市场环境下电动汽车的车-网互动响应模型,分析不同充放电方式下电动汽车的需求响应能力,为电动汽车参与市场环境下电网调度控制提供模型基础;然后,计及配电网运营商对需求侧灵活性资源的聚合作用,以购买电力和灵活性资源总成本最低为目标,构建考虑电动汽车充放电方式的输配协同能量-灵活性市场出清模型,通过协调控制输配电网中各类灵活性资源来满足输电网的灵活性需求;最后,通过修改的IEEE 33节点输电网与2个IEEE 33节点配电网耦合的测试系统对所提输配协同能量-灵活性市场出清方法的有效性进行分析与验证。结果表明,所提方法可提升电力系统的运行经济性和灵活性。

含垃圾能源化处理及电动汽车负载的区域综合能源系统协调优化

传统能源系统互相独立、欠缺联动,容易导致能量的浪费,并且能源结构也难以优化。区域综合能源系统具备多能互补、高效利用的优点,是提高能源利用效率和环保性的重要改进技术。为了利用垃圾蕴含的能量和电动汽车负载端的能源消纳,文中建立一个考虑垃圾焚烧和电动汽车负载的区域综合能源系统模型,利用模型进行系统的优化调度研究。论文分析了系统内的多能源能量流通关系,而后对系统内的各种能源转换设备及电动汽车进行分析,引入垃圾能源化处理,将热能转化为电能,并利用电动汽车进行电能消纳的模式,得出区域综合能源系统的能源效益最大化的模型。通过python进行算例分析,结果表明,含垃圾处理和电动汽车参与的区域综合能源系统既能提高能源的利用效率,又能带来更优的经济效益。

多轴分布式电驱动车辆电液复合制动控制研究

针对多轴分布式电机驱动车辆电液复合制动中易出现的车辆制动抖动问题,提出了一种建压阶段电机制动力修正策略和一种基于前馈-反馈的协调控制策略,分别在建压阶段和其他阶段通过协调复合制动力来解决制动抖动的问题。针对防抱死控制系统与电机制动系统共同作用时的制动矛盾,提出了一种基于PID控制的ABS控制策略,主要通过改变电机制动力来解决制动矛盾的问题。通过TruckSim、Matlab/Simulink及AMESim联合仿真验证,制动冲击度在建压阶段下降了20.66%,在电机退出阶段下降了92.59%,驾驶感觉得到明显改善。而ABS控制策略也可在保证理想滑移率的同时完成制动能量回收;结合整车制动试验,表明协调控制策略在保证制动效果良好的同时实现了制动能量回收,效果显著。