An activity chain model and its application to global design

In this paper, the "Activity Chain Model" is described, which is a new desi gn information model necessary for realizing a computer medium with which d esigners can dynamically share a wide range of design information containin g process information such as the history and the intent. We implement the model in a computer system, and confirm the validity of the model. It is difficult for existing design information models to provide both inte nt-capturing and intent-explanation capabilities sufficiently. The Activity Chain Model introduces a chained structure into the activity in order to s olve this difficulty by improving the explanation capability, and easily an d efficiently capturing the design intent based on the action-based intent description. The model integrates both the product and the process based on the activity description. In the Activity Chain Model, product information is described by the "produ ct units" associated with each other through "composition relations." The p rocess information about the history of the design is described by the "act ivity units" associated with each other through the "sequence relations" ac cording to the order of design activity executed along the time axis. Betwe en a product unit and an activity unit, we consider the "object relation." We also consider a "constraint relation" and an "alternative relation" betw een the activity units as the relations concerning the design intent. The " constraint relation" denotes that a certain activity unit in the past is a constraint of a succeeding activity unit. The "alternative relation" denote s that a certain activity unit is an alternative of another activity unit. The "causal reasons" and the "teleological reasons" are described as attrib utes of the constraint relations and alternative relations, respectively. " Reason" here denotes the designer viewpoint in determining the correspondin g relation. The hypothesis underlying the model is that the designer's inne r (mental) process which forms the design intent can be represented as a ch ain structure of the external activity units. The Activity Chain Model supports the capture of the design process informa tion, including design intent, according to the level of detail of the proc ess information. Consequently, the designer's input overhead can be mitigat ed at each detail level. In addition, we can use the same integrated model to capture, accumulate, and transfer the design process information. The POET (Process-Oriented Engineering Technology) Knowledge Medium impleme nting the Activity Chain Model is a computer system for the global design w hich is a new design style based on collaboration between designers beyond the physical restrictions of time and space. From the results of the evalua tion of the POET Knowledge Medium through design simulation, the effectiven ess of the Activity Chain Model was confirmed, not only in capturing and tr ansferring the design intent, but also in reminding the designers themselve s of the design process. By using the POET Knowledge Medium, it is expected that knowledge and expertise concerning design can be shared on an organiz ational level, and that creative high-quality design using ideas from previ ous outstanding designs will be realized.