Kinematic modelling for robot calibration

There is a considerable amount of literature dealing with robot calibration. A classification hierarchy of calibration procedures is discussed which groups robot calibration by objective. The state of the art for each classification is discussed with citations from recent literature. Several proposed models are described. Based upon the common assumption of all lower pair joints, three concepts are discussed which may be applied for comparing most of the calibration models proposed in the literature. These concepts are completeness, equivalence, and proportionality. Each of these are discussed in detail in the text. Attention is also paid to the possibility that joints may actually be higher pairs. Although this possibility is commonly accepted in coordinate measuring machine calibration, it is not widely recognized in the robot literature. The paper discusses possible causes and effects of higher order joint pairs and demonstrates how they might be modeled.