Web环境下协同装配系统的并发控制

通过对网络环境下协同装配操作的分析,总结了客户端执行结果不一致、多客户端误抓零件、多客户端同时装配同一零件、合理并行装配受阻以及装配约束冲突等5种并发装配冲突.提出了一种层次混合并发冲突控制模型(HCM,Hierarchical Hybrid Concurrency Conflict Control Model),HCM分上下两层,集成了4种并发控制策略,采用将具有装配语义的命令进行传输实现并发控制.上层采用基于全局装配序列的并发控制策略,整体上避免了前两种并发冲突;下层集成了装配操作序列化、系统加锁和用户解锁以及建立装配约束库等策略,消解了后3种并发冲突.基于HCM开发了一个原型系统,并结合实例验证了该系统的灵活性和有效性.

Concurrency control of collaborative assembly system under web environment

Based on the analyses of collaborative assembly operations under the web environment, five types of concurrency assembly conflicts were summarized, which are the inconsistent results produced by multi-clients, multi-clients grasping the wrong parts simultaneously, multi-clients assembling the same parts or subassembly in parallel, feasible concurrent subassembly operations being prevented and conflicts of assembly constraints. A hierarchical hybrid concurrency conflicts control model (HCM) was proposed, comprising two control layers and integrating four kinds of concurrency control strategies. The two former concurrency conflicts were eliminated effectively with the concurrency control strategy based on global assembly sequence integrated in the upper control layer. The rest three concurrency conflicts were resolved by the serialization strategy of assembly operations, server-locked and client-unlocked strategy and the strategy of designing assembly constraints library respectively which were integrated in the lower control layer. Finally, a prototype system has been implemented to test the concurrency control strategies, and the results show that the system is flexible and efficient.