A temporal framework for assembly sequence representation and analysis

A unifying temporal logic framework is proposed for modelling, specifying, and analyzing mechanical assembly sequences. Propositional temporal logic of Manna and Pneuli is the assertion language used for representing and analyzing all constraints or conditions that assembly sequences must satisfy. The generalization of the existing representations through the proposed framework is demonstrated. A new concept of reverse-equivalence, relating assembly and disassembly forms of knowledge, is introduced. It is shown that existing and new assembly sequence properties can be formulated and rigorously proved via mechanical theorem proving based on two assembly process-axioms, and the language inference rules and theorems. Comparison of the proposed framework with the existing representation schemes highlights the main strengths of the proposed framework, viz., temporal expressiveness, strong mechanical manipulation capability and precise formalism. The implementation of the framework on an IPC SUN SPARC workstation using Quintus Prolog for automatic generation of assembly sequences is described. A simple example illustrates the use of the proposed framework for representation, evaluation and selection of feasible assembly sequences