Rose and Galen were nearly knocked from the path when a riderless, wild-eyed horse galloped by.

一匹无人驾驭的马儿疯跑过来，差点就把萝丝和加仑撞出小路。

Their riderless contraption, which sports two extra backwards-rotating wheels and a front wheel that touches the ground in front of the steer axis, can still coast stably.

他们的没有驾驶者的新发明，安装有两个反转的轮子，在转向轴之前还有一个触地的轮子，这样在滑行状态也能稳定。

Internal and overseas research actuality was summarized in this paper, existent problems was analyzed, and then primary development direction of riderless bicycles was presented.

本文综述了国内外的研究现状，分析了所存在的问题，并指出了自行车机器人未来的主要发展方向。