This article presents two distinct manoeuvres allowing an articulated robot in free fall to change its orientation using closed paths in the joint space. It is shown through dynamics simulations that the magnitude of the net rotation is dependent upon the amplitude of the angular displacement of the joints. With realistic joint limitations, the robot, which includes rotary actuators only, can perform a 180 $^\circ$ reorientation about its longitudinal axis, similar to the cat righting reflex. The second manoeuvre allows the robot to accomplish rotations of smaller magnitude about a different axis. A physical prototype and a VICON motion tracking system are used to experimentally validate the simulation results. Finally, it is shown that the two manoeuvres, which yield rotations about fixed axes, can be repeated and alternated to enable the robot to reach any arbitrary 3-D orientation.

中文翻译：

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由猫扶正反射启发的自由落体机器人重新定向动作的设计和实验验证

本文介绍了两种截然不同的操作方式，使关节运动的机器人可以自由下落，并使用关节空间中的闭合路径来更改其方向。通过动力学仿真表明，净旋转的大小取决于关节的角位移的幅度。由于存在实际的关节限制，仅包含旋转执行器的机器人可以执行180 $ ^ \ circ $围绕其纵轴重新定向，类似于猫的正向反射。第二种操作使机器人可以绕另一个轴完成较小幅度的旋转。物理原型和VICON运动跟踪系统用于实验验证仿真结果。最后，显示出可以绕固定轴旋转的两个动作可以重复并交替进行，以使机器人能够达到任意的3D方向。