Calibration of industrial manipulators

The basic aim of a manipulator is to move its end-effector in a specific position or along a trajectory defined within its workspace. Since the end-effector can be considered as a rigid body in a three-dimensional space, it is necessary to define both its position and orientation for its unambiguous determination. The combinationof position and orientation is called pose. When a certain pose is required to the robot, in general, it will not be able to reach such a pose exactly, but will come extremely close. Additionally, if the same pose is required several times, the robot will respond with slightly different poses. In such context, it is possible to consider various methods to evaluate the capability of a particular manipulator to reach a command pose or an ordered set of poses. In the first section, some of the performance criteria for manipulating industrial robots and the related test methods will be presented. The second section will deal with the leading causes of the pose errors of the end-effector, that is, the source and significance of the manipulator errors. After having contextualized the problem and supplied the necessary notions, the subsequent sections will discuss the most common approaches implemented to augment the robot's performance.