|
A liaison information based assembly model is formulatedto
facilitate computer-aided assembly planning and analysis.Liaison
information, consisting of contacting and fitting information,
is systematically specified by the planner following the
presented guidelines, which are well-definedby a variety of
symbols to represent mating conditionsbetween a pair, based on
geometrical relations, of parts.Formulation rules are therefore
defined to generate assemblyprecedence constraints form the
specified liaison information.Two types of assembly constraints
are defined namely sandwichedand blocked constraints. To
facilitate assembly sequence planning evaluation, a practical
cost function is presented toincorporateassembly instability,
gripper changeover, assembly stroke reorientation,supporter
flipover, and fixturing complexity.Three feasible assembly plan
searching algorithms are presented: a depth-first searching
algorithm, a heuristic algorithm, and a genetic algorithm. These
algorithms are used to illustrate the possible optimal assembly
sequences. To study the influence of parameters used in the
presented genetic algorithm and to obtain an appropriate
combination of parametersused in the presented genetic algorithm
and to obtain an appropriate combination of these parameters,
experiment design is conducted and result is presented. Assembly
examples are used to show the use of thesealgorithms. Moreover,
a PC based computer-aided assembly planning and analysis system
is developed with user-friendly graphics userinterface and
graphics animation.
|