Positioning and orientation in modular robot systems

In a modular robot system the configuration is defined by the user, according to applications. Variations can occur in terms ofthe total number of axes, the axes in each cluster and the location of each cluster. This set-up differs from the normal robot kinematics analysis where the robot motion can be modelled using a series of successive coordinate transformations. This paper describes an approach to the solution of axes problems using an expanded transformation matrix formulation relating the cluster coordinates to the global coordination system. The global transformation concept has been illustrated in an application using two single axis robots. The hierarchical control software resides in a supervisory personal computer which maintains the required global transformation matrices and performs the real-time computational tasks of axes controls. The system is organised as a two and a half levels hierarchy in which the intermediate half-level is required to cope with the differences in communication protocols among different types of single axis robots.