The constraints on assembly plans vary depending on the 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 sequencing 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. Replanning is fast enough to enable 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. 12 refs., 2 figs., 3 tabs.
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