The invention discloses differing embodiments of calibration apparatus, and methods of use. In one embodiment, the calibration apparatus may be used to calibrate a tool, positioning system, robot, machine, or device. The calibration apparatus may include a first member adapted to be attached to a tool,...http://www.google.com/patents/US7277811?utm_source=gb-gplus-sharePatent US7277811 - Calibration apparatus and process
