基于hp自适应伪谱法的自主泊车路径规划

针对自主泊车路径规划最优控制问题求解收敛速率慢的问题,提出基于hp自适应高斯伪谱法的自主泊车路径规划方法。首先建立车辆运动学模型,并考虑自主泊车过程中避障约束和边界约束,再以泊车时间最短为性能目标函数,将自主泊车路径规划问题转化为最优控制问题。采用高斯伪谱法对最优控制问题进行离散化处理并采用序列二次规划进行求解,在求解过程中通过动态调整网格区间个数和多项式阶数实现提高求解收敛速率。根据实际场景选取4种工况并进行路径规划仿真,并将3种伪谱法进行对比分析,仿真结果表明hp自适应高斯伪谱法能够提升自主泊车路径规划最优控制问题求解收敛速率,同时该算法可以实现在狭窄泊车位内的泊车路径规划,通过实车试验验证提出的方法获得的自主泊车路径的有效性。     

多约束双向自动平行泊车轨迹规划

针对不能满足后退式平行泊车要求的狭小车位,提出两种双向平行泊车方式：平移式双向平行泊车、自由式双向平行泊车。根据两种泊车方式车辆轨迹特点,分析泊车过程中存在的可能性碰撞,选择合适的轨迹函数变量,建立碰撞约束函数,以泊车车位尺寸最小化为目标,利用MATLAB软件非线性约束优化功能求解最小车位尺寸,以轨迹半径最大化为目标对某一泊车环境进行泊车轨迹规划。仿真结果表明相同的泊车环境下,两种方法均可实现小车位安全泊车,但相比平移式双向平行泊车,自由式双向平行泊车方法能实现车辆安全进入更小车位;相同泊车环境及车位大小情况下,自由式平行泊车能更轻便地完成泊车。     

基于入位基准线的避死区自动泊车路径规划

为避免自动泊车过程中出现泊车死区,提出一种在车位外部汽车自动向前行驶至前进水平线的轨迹计算方法;为了减小泊车所需的车位长度,研究了由前进水平线倒车泊入车位,并保证该泊车轨迹经过入位基准线的方法。通过确定出的几个必须经过的定点坐标,利用插值样条理论与几何数学,确定出汽车在车位外部的泊车路径及其函数,且该函数具有唯一性,因此减少了自动泊车过程中系统不断进行反馈与纠正的计算过程。通过实验车的模拟验证,证明了路径规划的正确性。利用CarSim软件进行泊车过程的运动仿真,并对绘制出的轨迹线进行分析,结果表明该方法能控制汽车自动前进至非泊车死区位置,并可以减少对泊车所需车位长度的要求。     

基于场景驱动与分层规划的自主代客泊车系统研究

定义了自主代客泊车系统设计与测试验证的功能场景,并基于场景定义建立了环境模型。自主代客泊车系统的功能实现主要包含路径规划层与行为层。基于V2I通信系统服务与Reeds-Shepp Car曲线生成了自主代客泊车系统的全局参考路径,采用三次样条拟合曲线进行了路径平滑,利用车辆非线性约束模型、预瞄控制理论与动态面控制技术设计了用于轨迹跟踪的横向控制器。最后,在PreScan-MATLAB联合仿真环境下实现对自主代客泊车系统的功能集成与有效性验证。     

自动垂直泊车控制算法研究

在无人驾驶快速发展的当下,高级辅助驾驶系统(ADAS)作为无人驾驶的基础,需要逐渐完善以保证驾驶员在行车过程中的安全.在泊车过程中,驾驶员会被障碍物遮挡视线,同时会因为紧张引起不必要的交通事故,对经验欠缺的驾驶员会增加一定难度.研究了自动垂直泊车的路径规划问题,在Matlab中构建了汽车运动模型、泊车位模型、模糊逻辑控制器,针对垂直泊车路径规划问题,参考驾驶员经验,提出了一种基于模糊控制的垂直泊车三段式路径规划方法.仿真结果验证了此算法可以使车辆能够较高质量完成泊车过程.     

基于Matlab的自动泊车系统

文章基于多传感器数据融合级数讨论泊车的路径规划及算法,通过车辆泊车的起始点坐标、转向角以及后轮轴中心的运动轨迹方程计算出泊车的终点坐标,即后轮轴中心点的坐标,然后建立GUI对象,编辑界面布局,最后编写相应的程序代码。经测试,系统实现了自动泊车路径规划的初始化即初始点位置、仿真、停止仿真和留下轨迹功能。仿真的结果可以表明本设计采用的算法能够有效地完成自动泊车,不过系统仍有进一步优化的可能性。     

线控四轮转向汽车自主代客泊车路径规划

针对线控四轮转向汽车自主代客泊车路径规划问题,提出了一种对动态障碍物具有自适应能力的自主代客泊车路径规划方法.首先,采用栅格地图描述停车场环境信息,将连续状态空间中的自主代客泊车路径规划问题转化为离散状态空间中的自主代客泊车路径规划问题,并采用各向同性的圆形结构元素对栅格地图进行膨胀处理,使规划的自主代客泊车路径与障碍...     

基于FPGA的模糊控制自动垂直泊车系统设计

设计了一种基于FPGA的模糊控制自动垂直泊车系统,结合垂直泊车的实际情况、自动泊车系统的组成搭建了基于FPGA的PID模糊控制自动垂直泊车系统的硬件结构,采用超声波传感器采集周围环境数据,应用 PID模糊控制器对采集的信息进行分析处理.经测试,设计的系统在模型车航向角-34°~34°内,能够实现自主无碰撞泊车,达到了预期效果.     

多信息融合自动泊车系统研究综述

自动泊车系统能帮助驾驶者更好地进行泊车操作,减少泊车时的心理压力.为了增加泊车系统的应用场景及成功率,对多信息融合自动泊车系统的关键研究进行了归纳与总结.从车位识别传感器、路径规划、控制器、传感器多信息融合体系的研究分析中介绍了多信息泊车系统现状,提出了泊车系统发展中存在的问题与挑战.     

车辆平行泊车系统路径规划与控制研究

从路径规划和曲率优化两个方面建立平行泊车路径体系,提出了避障约束和曲率约束2种指标,以阿克曼转向为基础建立数学模型,通过避障约束分析得到车辆轨迹的相关参数,并且用五次多项式对路径曲率进行了优化,结果表明车辆可以安全平稳进入泊车位内.     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.