【作者】 刘兵；

【导师】 朱顺应；

【作者基本信息】 武汉理工大学 ， 交通运输规划与管理， 2008， 硕士

【摘要】 本论文以国家自然科学基金项目——基于视觉光流率和边缘率的车速控制理论与方法研究(项目编号:50778142)为依托。人的因素是引起交通事故的主因。根据日本有关资料,将近90%事故是由机动车驾驶人和行人造成。在驾驶员获取信息中90%以上是视觉信息,驾驶员主要通过周边视觉信息来感知车速及车辆位置,然后进行判断、决策、行动。可见,如何从事故主因—驾驶员出发,改善其视知觉信息,提前控制车速、保持车道,实时地采取与道路线形相适应的速度、轨迹运行,对提高道路交通安全水平具有重要的现实意义。论文首先分析了驾驶员视觉特性,包括:驾驶员视野、注视点以及影响视觉注意的因素。然后分析了影响速度感知的视觉因素,包括:边缘率、光流率、对比度,并从时间频率、空间频率、角速度、生理心理等角度解析了各因素的影响机理。在此基础上论文根据边缘率概念和物体运动方程推导了驾驶员在舒适性匀减速下保持边缘率恒定时的边缘率控速设计模型。用3DMAX制作了小汽车在高速公路上行驶时的边缘率实验影像,采取迫选法设计了主观等同速度实验方案260个,通过6男2女观测实验发现边缘率为12HZ时速度高估值最大,并把此边缘率作为合理值。根据实验结果对高速公路上从120km/h减速到90km/h的边缘率密度进行了设计。接着对雾天驾驶员速度感知机理及改善措施进行了研究。针对以往实验中采取全局浓度保持恒定的雾的缺陷,用3DMAX制作了小汽车在接近真雾环境下(实验场景中,驾驶员眼中雾的浓度呈线性变化)高速公路上行驶时的实验影像。采取迫选法设计了主观等同速度实验方案135个,通过6男2女共21600人次观测实验发现雾天对驾驶员的速度感知产生双向影响。当能见度很小(如39m时)会产生速度的高估,当能见度较高时会产生速度的低估,这与Snowden和Anstis的单向影响不一致。论文从光流率和对比度的角度解析了实验结果不一致产生的原因。能见度低时,近处光流率大是导致驾驶员产生速度高估的原因:能见度较高时,对比度的下降是导致驾驶员产生速度低估的原因。最后提出了基于边缘率的改善措施,通过速度感知实验得到边缘率为12HZ时其感知速度最大,以此边缘率作为雾天车速控制的合理值。最后论文对现有车道保持的理论进行了归纳总结,包括基于光流和视网膜流的车道保持理论、基于注视点的车道保持理论和基于扩张角的车道保持理论,解析了各理论存在的缺陷。更多还原

【Abstract】 Human factor is the primary cause which causes traffic accidents. According to the Japanese statistic data, about 90% accidents were caused by the vehicle driver and the pedestrian. Vision information account for above 90% of all the information which drivers gain in the driving, drivers mainly use the peripheral vision information to percept the vehicle speed and the vehicles position, then carry on the judgment and decision-making. Obviously, to raise the road traffic safety, it is important to improve drivers’ perception information to make drivers advance control vehicle speed, keep lane and real-time adopt the speed which adapts with the road geometry.Firstly, this paper analyzes the driver’s visual characteristics, including: visual field, gaze as well as factors which influence visual attention. Then this paper analyzes visual factors which influence speed perception, including: the edge rate, the optical flow rate and the contrast, then analyzes the influence mechanism from temporal frequency, spatial frequency, angular speed, physiological psychology. Based on the above analysis, according to the concept of edge rate and Newton’s equation of motion, the speed control design model which based on the assumption that the driver maintains the constant edge rate with the comfortable deceleration rate is deduced. By using the 3DMAX, the edge rate experiment videos that car moving on the highway are made, we design 260 stimulation of Subjectively Equal Speed experiments by using the Forced-Choice Method, through 6 males and 2 females’ experiment results, we find that driver’s speed perception value is the largest when the edge rate is 12HZ, but the difference between 8HZ and 16HZ is litter, considering driver’s speed perception value is the largest when the edge rate is 12HZ under the fog environment, then we select 12HZ as the reasonable value. According to experiment result, we design the edge rate spacing for controlling the speed from 120km/h to 90km/h.Aiming at previous study used uniform reduction of the image contrast, we made experiment video that car moving on the highway in real fog environment with 3DMAX (the density of fog increased linearly with visual distance). 135 Subjectively Equal Speed experiments were designed by using the Forced-Choice Method, 6 males and 2 females’ experiment results indicated that fog exerts a two-way influence to the driver’s speed perception. When visibility was low (e.g:39m), fog resulted in overestimation of the speed, When visibility was higher, fog resulted in underestimation of the speed, it is not in accordance with one-way influence of Snowden and Anstis. Have analyzed the reason why the experimental result is inconsistent and emerge in terms of light stream rate and contrast ratio in thesis. When visibility is low, the nearby optical flow rate is great which cause the driver overestimate the speed; When visibility is higher, the decline of contrast cause the driver underestimate the speed. Finally, the improvement method which based on the edge rate was proposed, through speed perception experiment, driver’s speed perception value was the largest when the edge rate was 12HZ under the fog environment, then 12HZ was selected as the reasonable value.Finally, the paper carries on the induction and summary about the existed vision-based lane-keeping theory, including: (1) lane-keeping theory which based on the optical flow and retina flow; (2) lane-keeping theory which based on the gaze point; (3) lane-keeping theory which based on the splay angle.更多还原