In programming robot manipulators to carry out a wide variety of tasks it w
ould be desirable to create a CAD system in which these tasks can be progra
mmed at the task level, leaving the fine-grained detail of path planning an
d collision detection to the system. This paper describes the theoretical b
ackground to such a system, by providing a model in which robot motions are
represented using multivariate B-splines, a standard representation for fr
ee-form shapes in the CAD environment. The paper also describes algorithms
which take this representation and apply it to collision detection and path
-planning.