Research on Concurrency Control in CAD Cooperative Design Based on HLA

In order to implement concurrency control of three dimension CAD product in real-time cooperative design, a conflict resolution strategy that combines the services of object ownership management and time management in high level architecture (HLA) with datapsilas dynamic locked was proposed, meanwhile, the federates with different authorities and functions were defined and a distributed virtual design system framework was constructed. In this method, the transfer of designer authority can be implemented by push and pull modes, namely, the federate which initiates object ownership transfer can actively request divesting or obtaining the authority. According to setting the level of time management and the mode of time advance, the system can effectively control concurrent events by using operation serialization based on time stamp and object locking mechanism. In addition, in order to cooperate the design works of each federate and negotiate resolution conflict in the process of cooperative design, a cooperation awareness model and interceder mechanism was developed in management federate.