The authors describe a general-purpose, representation-independent method for the accurate and computationally efficient registration of 3-D shapes including free-form curves and surfaces. The method handles the full six degrees of freedom and is based on the iterative closest point (ICP) algorithm, which requires only a procedure to find the closest point on a geometric entity to a given point. The ICP algorithm always converges monotonically to the nearest local minimum of a mean-square distance metric, and the rate of convergence is rapid during the first few iterations. Therefore, given an adequate set of initial rotations and translations for a particular class of objects with a certain level of 'shape complexity', one can globally minimize the mean-square distance metric over all six degrees of freedom by testing each initial registration. One important application of this method is to register sensed data from unfixtured rigid objects with an ideal geometric model, prior to shape inspection. Experimental results show the capabilities of the registration algorithm on point sets, curves, and surfaces.>

The control of industrial robots is usually divided into several sequential stages. Trajectory planning is an important off-line stage which is concerned with the generation of a time history of a robot's joint position, velocity, acceleration, and input torques. A number of trajectory planning methods have been developed [1], [4]-[6], [10], [11], [13], which usually entail complex computations and algebraic manipulations. Programming this sort of trajectory planners is very complex and error-prone, thereby limiting their applicability. To remove this limitation, we have begun the development of software for automating the trajectory planning, called the Automatic Trajectory Planner Generator (ATPG). This paper describes important components of the ATPG: three trajectory planners, data structures for describing geometric paths, generation of the robot's dynamic equations and constraint functions, and ancillary software. A large portion of the ATPG has been completed, and the remaining portion is currently under development.