Utility for calibrating cameras and RGB-D sensors to a robot arm holding a checkerboard. The optimization procedure takes a set of 3D checkerboard corner detections and corresponding end effector poses to find the both, the transformation between the end effector and the checkerboard frame, and the transformation between the /base_link and the sensor's frame. The assumption is that the pose of the checkerboard with respect to the end effector is fixed, and that enough samples are obtained such that the checkerboard offset can be uniquely determined. In practice, having over 12 checkerboard captures is recommended such that all 6 degrees of freedom of its pose are expressed in the sensor.
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