Constraints on assembly plans vary depending on product, assembly facility, assembly volume, and many other factors. Assembly costs and other measures to optimize vary just as widely. To be effective, computer-aided assembly planning systems must allow users to express the plan selection criteria that apply to their products and production environments. We begin by surveying the types of user criteria, both constraints and quality measures, that have been accepted by assembly planning systems to date. The survey is organized along several dimensions, including strategic versus tactical criteria; manufacturing requirements versus requirements of the automated planning process itself; and the information needed to assess compliance with each criterion. The latter strongly influences the efficiency of planning. We then focus on constraints. We describe a framework to support a wide variety of user constraints for intuitive and efficient assembly planning. Our framework expresses all constraints on a sequencing level, specifying orders and conditions on part mating operations in a number of ways. Constraints are implemented as simple procedures that either accept or reject assembly operations proposed by the planner. For efficiency, some constraints are supplemented with special-purpose modifications to the planner's algorithms. Fast replanning enables an interactive plan-view-constrain-replan cycle that aids in constraint discovery and documentation. We describe an implementation of the framework in a computer-aided assembly planning system and experiments applying the system to a number of complex assemblies, including one with 472 parts.

Constraints on assembly plans vary depending on product, assembly facility, assembly volume, and many other factors. This paper describes the principles and implementation of a framework that supports a wide variety of user-specified constraints for interactive assembly planning. Constraints from many sources can be expressed on a sequences level, specifying orders and conditions on part mating operations in a number of ways. All constraints are implemented as filters that either accept or reject assembly operations proposed by the planner. For efficiency, some constraints are supplemented with special-purpose modifications to the planner's algorithms. Fast replanning enables a natural plan-view-constrain-replan cycle that aids in constraint discovery and documentation. We describe an implementation of the framework in a computer-aided assembly planning system and experiments applying the system to several complex assemblies.

This paper is a survey of constraints used in automated assembly planning, where "constraints" are interpreted broadly to include requirements, preferences, and suggestions to the planner. We list a large number of constraints that have appeared in the assembly planning literature and categorize them along several dimensions. These dimensions include strategic vs. tactical constraints; requirements vs. criteria to optimize vs. suggestions; and constraints encoding manufacturing requirements vs. those imposed by the automated planning process itself. We also consider the information needed to assess each constraint, particularly as it affects the efficiency of planning with the constraint. Finally, we present our planned framework for incorporating many of the surveyed constraints into an interactive version of the Archimedes assembly planner.

We describe the implementation and performance of Archimedes 2, an integrated mechanical assembly planning system. Archimedes 2 includes two planners, two assembly sequence animation facilities, and an associated robotic workcell. Both planners use fully 3 dimensional data. A rudimentary translator from high level assembly plans to control code for the robotic workcell has also been implemented. We can translate data from a commercial CAD system into input data for the system, which has allowed us to plan assembly sequences for many industrial assemblies. Archimedes 2 has been used to plan sequences for assemblies consisting of 5 to 109 parts. We have also successfully taken a CAD model of an assembly, produced an optimized assembly sequence for it, and translated the plan into robot code, which successfully assembles the device specified in the model.

Abstract The XERROR package is a collection of portable Fortran routines for processing of errors that occur in other routines. It was developed as the error‐handling package for the SLATEC Common Mathematical Library, which is currently in use at a number of U.S. Department of Energy and other facilities. This paper describes how to use the package, from the viewpoint of the writer of library routines that need to call the XERROR package to handle errors, and from the viewpoint of the user of those library routines.

Usage of mathematical library (MATHLIB) routines on the Control Data 6600 system at Sandia Laboratories, Albuquerque, New Mexico, has been momtored for over three years.The value of one input argument during the first execution of each library routine in each job along with the identification number of the user has been monitored for about two years.The selection and implementation of the method used for monitoring and the impact of monitoring on the user and on the system are discussed.The significance of the usage data is discussed for several actual applications, and additional possible uses of the data and planned extensions of monitoring are mentioned.