Reconfigurable fault-tolerant controller synthesis for a steer-by-wire vehicle using independently driven wheels

In this paper, a synthesis method for a reconfigurable fault-tolerant control system for use in a steer-by-wire vehicle is proposed. The vehicle considered in this paper is also assumed to have independently driven wheels. The control objective in this work is to enable the vehicle yaw rate to track the reference signal even when the steering actuator breaks down. Since the vehicle yaw rate can be controlled with either the front wheel turn angle or the yaw moment generated by the independently driven wheels, this system has actuator redundancy. We attempt to design a control system that manages this actuator redundancy so that the performance degradation due to the actuator failure is minimised. We utilise a control allocator based on on-line optimisation for managing the actuator redundancy. The fault-tolerant control system with a control allocator has several excellent properties. For example, the method can handle various failure situations. Also, since the control allocation problem is reduced to a convex quadratic programming problem, the on-line computational effort is relatively little. However, so far, it has been unclear whether the stability of the control system with the control allocator is guaranteed when the actuator failure occurs. Therefore, we propose a design method of a fault-tolerant controller based on on-line optimisation that guarantees the stability of the overall system. The effectiveness of the method is established through numerical examples.     

履带式铣刨机的作业原理及功率分配研究

本文对铣刨机的液压行走系统和铣刨宽度、传动方式与铣削作业系统的进行了分析。在结合发动机特性曲线基础上,探讨了铣刨机发动机功率分配的原则。铣刨机功率分配的原则应为保证各系统功率之和与发动机目标值功率相一致,使机器有最好的动力性、经济性和作业生产率,可以为铣刨机设计提供参考。     

出口箱随机入港下的集装箱码头泊位调度

针对港口竞争环境下产生的出口箱随机入港分散堆放策略,综合考虑出口箱堆场堆存位置分布以及泊位分配与集卡路径之间的相互影响,提出了出口箱随机入港下的集装箱码头泊位调度问题,并以船舶停靠泊位为决策变量,以所有集卡行驶总路径最短为目标函数,建立了泊位调度优化模型。采用基于遗传算法的启发式算法,对遗传算子进行了改进设计。最后,应用算例对模型和算法进行仿真实验,并将优化后结果与传统的先到先服务泊位调度模式进行比较分析。结果表明:以集卡行驶总路径为考量的泊位调度优化可使集卡行驶总路径缩短11.51%,可明显降低港口的运营成本,同时获得合理的泊位分配计划,模型和算法可行有效。     

基于预期偏移距离的人机权值分配策略研究

针对智能车辆横向运动控制中驾驶员和辅助系统的控制权限冲突问题,本文中提出一种人机权值分配策略。采用车辆在预瞄点处的预期偏移距离(PDLC)衡量车道偏离危险度,预期偏移距离通过对预瞄偏差修正获取。权值分配函数设计时以PDLC为自变量,以保证驾驶员的权值为优先控制目标,以一定的横向运动控制精度为先决条件。在CarSim/Simulink联合仿真平台和CarSim/Labview RT硬件在环实验台上对提出的控制策略进行了实验验证和数据分析。结果表明,采用权值分配策略协调驾驶员和辅助系统的控制,可在有效跟踪理想道路中心线的前提下保证驾驶员的控制权值,降低其工作负荷以及纠正驾驶员的误操作行为。     

共享停车泊位的分配-定价-收益分配机制

为科学管理共享停车资源,构建一种共享停车泊位的分配-定价-收益分配机制。首先,以存在多个地块的区域为对象,根据出行者对不同地块及停车时间模式的选择偏好构建停车许可证的最优分配-定价模型,其中,最优分配模型为组合拍卖竞胜标确定问题(NP困难问题)。其次,利用Benders分解原理、对偶理论及新型升价拍卖代理系统构建调优法对停车许可证进行拍卖。最后,为调动共享泊位提供者的积极性,利用沙普利值法构建基于对社会福利贡献程度的停车收益分配模型。由理论分析及数值试验可知,运用上述机制可精确实现社会福利最优状态,最小竞争均衡价格与公平的收益分配。结果表明:①相较VCG机制与Leonard机制,调优法不仅可精确求解停车许可证的最优分配-定价,而且在算法最坏时间复杂度方面拥有更高效率;②在调优法的每个步骤中,即使停车许可证的分配并非最优,通过机制所实现的收费定价依然具有防止策略性操作的重要性质;③调优法可在较少的步骤之内实现较高的社会福利;④新型升价拍卖代理系统拥有多项式型的最坏时间复杂度;⑤通过最优分配-定价机制可获得每位出行者的选择偏好,进而可计算不同泊位提供者组合条件下的社会福利,实现沙普利值法在现实应用中的可计算性。     

公路客运枢纽的班线组织与配置方法初探

针对公路客运枢纽班线配置问题，对班线组织和配置方法进行研究。在考虑公路客运枢纽布局的基础上，探讨了客运班线的组织和配置原则，提出班线组织主要是协调集约化和分散性两种需求。在总体思路的指导下，宏观配置方法结合场站体系和功能定位，提出了各类型场站班线配置策略；以宏观配置策略为指引，微观配置方法通过建立分区客流预测模型，依据各交通小区到各目标客运站的出行时间和最短路原则，确定各客运站对该类班线的市场划分情况，将该类班线的运力分配到各个客运站，使得总出行成本最小。     

Wheel slip control with torque blending using linear and nonlinear model predictive control

Modern hybrid electric vehicles employ electric braking to recuperate energy during deceleration. However, currently anti-lock braking system (ABS) functionality is delivered solely by friction brakes. Hence regenerative braking is typically deactivated at a low deceleration threshold in case high slip develops at the wheels and ABS activation is required. If blending of friction and electric braking can be achieved during ABS events, there would be no need to impose conservative thresholds for deactivation of regenerative braking and the recuperation capacity of the vehicle would increase significantly. In addition, electric actuators are typically significantly faster responding and would deliver better control of wheel slip than friction brakes. In this work we present a control strategy for ABS on a fully electric vehicle with each wheel independently driven by an electric machine and friction brake independently applied at each wheel. In particular we develop linear and nonlinear model predictive control strategies for optimal performance and enforcement of critical control and state constraints. The capability for real-time implementation of these controllers is assessed and their performance is validated in high fidelity simulation.     

铣刨机行走液压系统速度特性分析

本文以四轮驱动的冷铣刨机为研究对象,对冷铣刨机行走驱动液压系统的速度特性进行了分析,建立了冷铣刨机行走速度特性方程。同时,对利用冷铣刨机的行走速度来实现功率自动分配进行了分析,分析后认为,通过控制电磁阀电流可实现发动机功率的自动分配。     

On the goods-activities technical relations in the time allocation theory

In areas like household production and travel choice, time assigned to the different activities plays a key role in addition to consumption as the main variables in utility within the consumer behaviour framework. However, a comprehensive conceptual structure to understand the technological relations between goods consumption and the assignment of time to activities is still lacking. In this paper the problem is reviewed and all possible relations between goods and time are re-formulated. Two general functions are defined and proposed to account for all these relations, forming a new taxonomy for the technical constraints. The resulting consumer behaviour model is used to obtain general expressions for both the value of saving time in constrained activities like travel, and the value of leisure.