【導(dǎo)讀】ersityofHongKong,TatCheeA?enue,HongKong,cessplanningCAPP.

　　

【正文】 , including planning goals and constraints.. CoordinationThe cooperative problem solving is carried outamong the Bagent and Pagents. The Bagent isresponsible for storing and announcing the publicinformation involved in each process planning problem. It is partitioned into four areas for four distinctgroups of information: problem, proposal, evaluationand solution. The problem area contains the initialproblem definition and the overall requirements ofthe process planning problem. The proposal areastores partial and plete proposals at several layers of abstraction issued by the Pagents. A proposalfrom a Pagent might be evaluated by other Pagents.If there is any inaccurate or inplete process inthe proposal, other Pagents can put their critiquesrelated with the proposal to the evaluation area of theBagent. The evaluation area stores the conflicts thatoccur during the process planning, and provides ameans of munication among the Pagents whoare involved in the conflict. The evaluation resultsand conflict resolution remendations issued bythe Pagents are also recorded in the evaluation area.The solution area includes the evolving process planning template to which nonconflicting process mitments produced by the Pagents are added. Thefinal solution is recorded into the solution area of theBagent. The organization of the Bagent is shown inFig. 4. The inference engine provides the control ofinformation flow among the four areas. The knowledge base contains the event scheduling knowledgefor cooperative problem solving and the justifications of the solutions to the problems.The Bagent monitors the data of the four areas.Once a proposal is received from a Pagent, it will beplaced in the proposal area. At the same time, thePagent will check if the number of proposals for thesame problem is greater than a fixed value. If yes,the Bagent will choose the best proposal from theproposal list in the proposal area as a possible solution. The process planning for the problem will beFig. 4. Event trace for coordination.(). Zhao et in Industry 41 2020 83–97 91terminated. If not, the proposal will be posted toother registered Pagents for their review. Once anevaluation is received from a Pagent, the Bagentwill check if the evaluation has a conflict result. Ifthere is any conflict, the owner of the proposal willbe notified. The Bagent will coordinate these Pagents having conflict to settle by negotiation. Ifthere is no conflict, the Bagent will check if all theregistered Pagents have agreed with the proposal. Ifyes, the proposal will be evolved into a solution tothe problem.. CooperationAs mentioned previously, the CoCAPP systemenvironment is organized as a munity of cooperative problemsolving agents, where each Pagentis a relatively independent and autonomous knowledgebased expert system. The Pagent solves problems in its limited domain independently. Therefore,it should have the capabilities to act as a member ofa munity. These capabilities include:fl a shared munication language with otheragents。fl internal knowledge representations which capturesufficient goal and history information to allowfor solution revision to be carried out cooperatively。fl provisions for sharing information in a timelymanner for problemsolving。fl mechanisms for incorporating externally produced partial solutions。fl mechanisms for negotiation to settle conflicts。fl the ability to coordinate an internal agenda withexternal events.Each Pagent municates with other agents byusing a mon shared language. The proposal generation and evaluation, solution, and conflict generation and resolution are produced according to theinternal domain knowledge of the Pagent.4. Software implementationwxThe IBM ABE Toolkit 24 is chosen as thedevelopment environment of the CoCAPP system.The Visual Cqq language is chosen as the implementation language. The system can run in the platform of Windows 95 or Windows NT.Fig. 5. Conflict resolution of Pagents.(). Zhao et in Industry 41 2020 83–9792As mentioned, each Pagent in the CoCAPP system makes use of three types of knowledge: domainknowledge, control knowledge, and conflict resolution knowledge. In order to enhance the flexibilityand scalability, the domain knowledge is furtherclassified into universallevel, shoplevel, and machinelevel knowledge. The universallevel knowledge is applicable to any status without consideringindividual panies and is established when theCoCAPP system is in development and is often fixedafter the system has been constructed. The shopleveland machinelevel knowledge can be added andmodified by individual panies when the systemis scaled. The machinelevel knowledge is only applicable to a specific machine. The knowledge ofeach agent is implemented as a database or file.The conflict resolution handler is shown in Fig. 5.It consists of two effectors: ‘WatchConflict’ and‘ResolveConflict’, as well as one conflict resolutionfacts file and one conflict resolution rules file. The‘WatchConflict’ is used to map out the conflictproblem space and conflict situation. The ‘ResolveConflict’ is used to resolve conflicts. The conflictresolution strategies are implemented in this effector.Fig. 6. Test ponent.5. Case studyThe case study is used to illustrate the characteristics of the Machining CoCAPP system. The firstexample demonstrates the feedback due to an unreasonable product design. In this example, as an unreasonable part design is provided, the CoCAPP systemgenerates an ‘unresolved conflict’ output and reportsto the Dagent the locations and causes of the conflict. The part is shown in Fig. 6, a bar with anenvelope size of 50=40=30 mm3.. Initial Part Design Datatimeless:7200。Pa