中文摘要：

对合适的自动避碰时刻进行研究，通过对交通场景进行俯视拍摄的方法获得10．5 h真实的冲突视频录像，借助视频检测技术提取并分析808个冲突避碰行为样本，基于交通冲突技术的基本理论得出2点结论：1）群体驾驶人何时实施避碰取决于至碰时间TTC；2）避碰时刻与临界时刻之间具有至少1 s的裕量。将自动避碰系统的制动时刻设定在上述2个时刻之间，足够现有技术实现自动避碰任务。

英文摘要：

The purpose of the study is to find out the appropriate evasion time of collision avoidance system.By using the video cameras mounted on tall structures to acquire 10.5 hour video records of traffic streams at no-signal intersection, the thesis extrac-ted and analyzed 808 samples with the aid of video detection.Based on the traffic conflict technology, conclusions were drawn as follows：1） the basis for avoidance decision is time to collision （ TTC）;2） the activation time of CAS should be restricted within a definite range ,whose upper limit is the evasion time of normal driving and lower limit is the critical time .