! Roll-pitch-yaw angles to SO(3) rotation matrix. @param rpy Roll-Pitch-Yaw angles in radians. @param opt Order option. Acceptable inputs: - 'xyz' Rotations about X, Y, Z axes (for a robot gripper) - 'zyx' Rotations about Z, Y, X axes (for a mobile robot, default)
(rpy: ArrayType, opt: str = "zyx")