On a Relationship Between the Physical Features of Robotic Manipulators and the Kinematic Parameters Produced by Numerical Calibration

Although kinematic parameter estimation is well-established as a technique for improving the positioning accuracy of a robotic manipulator, little attention has been given to the relationship between the parameters of a kinematic model and the corresponding physical features of a manipulator. If each kinematic parameter of a robot corresponds to one and only one of its independent physical features, then a change in the value of an optimal parameter would reflect a change in the corresponding physical feature. This knowledge is of potential value in isolating the sources of wear and damage in a manipulator, and, more generally, in predictive maintenance. In this work, the choice of kinematic model is shown to have a strong effect on the physical feature/kinematic parameter relationship. The most suitable kinematic model for preserving this relationship includes redundant parameters, which may interact numerically among themselves during the parameter estimation process and may complicate the interpretation of results. On the other hand, a kinematic model with no redundant parameters contains too few parameters to establish a comprehensive physical features/kinematic parameters relationship. Multiple-site pose measurement has been explored as a method of preserving the desired relationship even in the presence of redundant parameters.