Robot calibration is a general term that means many different things depending on the goal of the user.  In general, robot calibration improves the robot accuracy of a given cell.  Robots can be “calibrated”, meaning just Mastered to zero encoder values, or fully calibrated (with consideration for all geometric and non-geometric parameters) for high absolute accuracy robotic applications. 

Calibration involves the process of first identifying (i.e. measuring) the accurate geometry of the robot, then compensating the robot’s programmed positions considering the actual geometry to eliminate the impact of manufacturing tolerances for that particular robot.

Robots can be calibrated either at the Robot Manufacturer’s facility for initial mastering, or absolute accuracy of the Robot itself.  Alternatively, the robot can be calibrated after installation of the robot with its End Effector and placement relative to the jig/fixture.  In this latter case, the calibration process can also determine accurate TCP and Alignment of the robot to the fixture.

Robot calibration is typically used to reduce manual programming time, improve process quality, or to enable standard robots to achieve accuracies of much more expensive equipment (i.e. CNC machines, CMMs, etc.).