Model-based constrained motion. a. Modeling, specification and control

Model-based constrained motion is presented as an extension to Mason's 'task frame' or 'compliance frame' formalism (1981). The basic model building blocks are the constraint's 'features'. Their explicit use of symbolical, geometrical and analytical models of the motion constraints increases the flexibility in specification and control. This results in a larger range of possible applications in uncertain environments, and better interfaces, not only to the human user, but also to the off-line task planner and the online task monitor and executor. This text describes the ideas underlying the 'feature frame' approach, as well as the extra programming and design efforts needed to realize the increased flexibility. A simple task is given as an example application: 'incompatible seam tracking'. This task cannot be specified, nor executed, by means of the classical task frame approach.<>