Using the technique of pedal coordinates we investigate the orbits of a free double linkage. We provide a geometrical construction for them and also show a surprising connection between this mechanical system and orbits around a Black Hole and solutions of Dark Kepler problem.

中文翻译：

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踏板坐标和自由双连杆

使用踏板坐标技术，我们研究了自由双连杆的轨道。我们为它们提供了几何结构，并展示了这个机械系统与黑洞周围的轨道以及暗开普勒问题的解决方案之间令人惊讶的联系。