履带式电驱动推土机直驶稳定性研究

为了解决电驱动推土机直驶跑偏问题,建立了履带式电驱动推土机仿真模型,利用仿真模型对推土机直驶稳定性影响因素进行了分析,分析结果表明,两侧驱动电机特性差异、两侧行动装置差异及两侧负载差异都会导致推土机直驶跑偏,且差异大小与跑偏量呈正相关。将推土机横摆角速度作为直驶稳定性控制的反馈参数,设计了基于模糊PID的电驱动推土机直驶稳定性控制策略。对有/无直驶稳定性控制的两种情况进行了对比仿真分析,结果表明,推土机横摆角速度可以控制在0 rad/s左右,验证了直驶稳定性控制策略的可行性。

带耦合机构的串联式履带车辆直驶稳定性控制

首先分析了串联式混合动力履带车辆耦合机构转矩与转速的输出特性及其对车辆直线行驶稳定性的影响,并利用MATLAB/Simulink仿真平台建立了整车动力学模型,其中考虑了履带的滑移率对附着系数的影响,其次为了提高车辆的直驶稳定性设计了相应的控制策略,即通过检测两侧车速的变化来计算两电机输出转矩的补偿量,并针对PI控制器参数适应性差的问题,通过神经网络自学习的功能实时优化PI控制器的控制参数.最后利用Simulink模型进行仿真,结果表明,神经网络PI控制能够保证车辆的直驶偏移量控制在0.5%左右,满足国家标准中最大直驶偏移量为1%的要求.

一种混凝土运输车横向行驶稳定性研究

文章对一种混凝土运输车在转弯时易产生侧翻现象进行了分析,得出了不同状态下横向行驶的临界状态,分析出混凝土运输车行驶稳定性的影响因素。对混凝土运输车的行驶车速进行了约束。

四轮独立驱动电动汽车直驶稳定性协调控制研究

针对四轮独立驱动电动汽车直线行驶跑偏及行驶稳定性问题,提出驱动转矩协调控制策略。该策略采用分层控制逻辑,上层控制逻辑层负责车速跟随控制、附加横摆力矩计算、驱动防滑控制;下层控制逻辑层负责驱动转矩协调分配。基于车辆动力学软件Carsim和MATLAB/Simulink搭建四轮独立驱动电动汽车协调控制系统仿真模型,在高附着、低附着和对开路面等典型工况进行仿真,结果表明,相比于转矩平均分配及无控制,协调控制策略使车辆横摆角速度保持在0±0.05(°)/s,且车轮滑转率控制在最优滑转率范围内,提高了车辆直驶稳定性。

分布式驱动电动汽车直驶稳定性的仿真分析

本文对轮毂电机进行了选型,应用Carsim和Simulink建立了包括速度控制模块在内的分布式驱动电动汽车的仿真模型,对前驱、后驱和四驱三种驱动方式在低附着系数路面上进行了仿真分析。结果表明在低附着系数路面上,后驱模式直驶稳定性相对较好。

履带车辆双电机耦合驱动系统同步特性

为提高双电机耦合驱动履带车辆直驶稳定性,从机械及控制两个方面对驱动系统输出同步问题进行研究。对驱动系统中的耦合机构负载均衡原理进行分析,得出耦合机构可以使其两个输出端的负载差传递到两个输入端后降低60%~80%.通过深入分析双电机耦合驱动系统同步运行的影响因素,提出基于模糊PID的偏差耦合同步控制策略,对两侧电机控制误差存在差异及驱动系统输出端存在不平衡负载状态下,有、无同步控制的情况进行仿真对比,并进行基于实车平台的双电机耦合驱动系统同步性能试验。仿真及试验结果表明,利用机械、控制相结合的方法很好地解决了双电机耦合驱动履带车辆直驶同步的难题。

Intelligent back-looking distance driver model and stability analysis for connected and automated vehicles

The connected and automated vehicles(CAVs)technologies provide more information to drivers in the car-following(CF)process.Unlike the human-driven vehicles(HVs),which only considers information in front,the CAVs circumstance allows them to obtain information in front and behind,enhancing vehicles perception ability.This paper proposes an intelligent back-looking distance driver model(IBDM)considering the desired distance of the following vehicle in homogeneous CAVs environment.Based on intelligent driver model(IDM),the IBDM integrates behind information of vehicles as a control term.The stability condition against a small perturbation is analyzed using linear stability theory in the homogeneous traffic flow.To validate the theoretical analysis,simulations are carried out on a single lane under the open boundary condition,and compared with the IDM not considering the following vehicle and the extended IDM considering the information of vehicle preceding and next preceding.Six scenarios are designed to evaluate the results under different disturbance strength,disturbance location,and initial platoon space distance.The results reveal that the IBDM has an advantage over IDM and the extended IDM in control of CAVs car-following process in maintaining string stability,and the stability improves by increasing the proportion of the new item.

Structural effect of a soft-hard backfill wall in a gob-side roadway

The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall.

Using improved particle swarm optimization to tune PID controllers in cooperative collision avoidance systems

The introduction ofproportional-integral-dorivative （PID） controllers into cooperative collision avoidance systems （CCASs） has been hindered by difficulties in their optimization and by a lack of study of their effects on vehicle driving stability, comfort, and fuel economy. In this paper, we propose a method to optimize PID controllers using an improved particle swarm optimization （PSO） algorithm, and to bettor manipulate cooperative collision avoidance with other vehicles. First, we use PRESCAN and MATLAB/Simulink to conduct a united simulation, which constructs a CCAS composed of a PID controller, maneuver strategy judging modules, and a path planning module. Then we apply the improved PSO algorithm to optimize the PID controller based on the dynamic vehicle data obtained. Finally, we perform a simulation test of performance before and after the optimization of the PID controller, in which vehicles equipped with a CCAS undertake deceleration driving and steering under the two states of low speed （≤50 km/h） and high speed （≥100 km/h） cruising. The results show that the PID controller optimized using the proposed method can achieve not only the basic functions of a CCAS, but also improvements in vehicle dynamic stability, riding comfort, and fuel economy.

Stability and a fast calculation method of travel speed of pulse peak in convergence zone

A long-range sound propagation experiment was conducted in the West Pacific Ocean in summer 2013.The signals received by a towed array indicate that the travel speed of pulse peak(TSPP)in the convergence zones is stable.Therefore,an equivalent sound speed can be used at all ranges in the convergence zones.A fast calculation method based on the beam-displace-ment ray-mode(BDRM)theory and convergence zone theory is proposed to calculate this equivalent sound speed.The computation speed of this proposed method is over 1000 times faster than that of the conventional calculation method based on the normal mode theory,with the computation error less than 0.4%compared with the experimental result.Also,the effect of frequency and sound speed profile on the TSPP is studied with the conventional and fast calculation methods,showing that the TSPP is almost independent of the frequency and sound speed profile in the ocean surface layer.

A Lattice Hydrodynamic Model for Trafc Flow Accounting for Driver Anticipation Efect of the Next-Nearest-Neighbor Site

In this paper, a new lattice hydrodynamic model is proposed by incorporating the driver anticipation effect of next-nearest-neighbor site. The linear stability analysis and nonlinear analysis show that the driver anticipation effect of next-nearest-neighbor site can enlarge the stable area of traffic flow. The space can be divided into three regions： stab/e, metastable, and unstable. Numerical simulation further illuminates that the driver anticipation effect of the next-neaxest-neighbor site can stabilize tramc flow in our modified lattice model, which is consistent with the analytical results.