An Activity Chain Model and Its Application to Global Design
Authors: Taura Toshiharu , Aoki Yasukazu , Takada Hiroshi , Kawashima Koji , Komeda Shinji , Ikeda Hajime , Numata Jun 
Published: March 2007

In this paper, the "Activity Chain Model" is described, which is a new design information model necessary for realizing a com puter medium with which designers can dynamically share a wide range of design information containing 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 intent-capturing and intent-explanation capabilities sufficiently. The Activity Chain Model introduces a chained structure into the activity in order to solve this difficulty by improving the explanation capabil ity, and easily and 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 "product units" associated with each other through "composition relations." The process information about the history of the design is described by the "activity units" associated with each other through the "sequence relations" according to the order of design activity executed along the time axis. Between a product unit and an activity unit, we consider the "object relation." We also consider a "constraint relation" and an "alternative relation" between 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 suc ceeding activity unit. The "alternative relation" denotes that a certain activity unit is an alternative of another activity unit. The "causal rea sons" and the "teleological reasons" are described as attributes of the constraint relations and alternative relations, respectively. "Rea son" here denotes the designer viewpoint in determining the corresponding relation. The hypothesis underlying the model is that the designer's inner (mental) process which forms the design intent can be represented as a chain structure of the external activity units.

The Activity Chain Model supports the capture of the design process information, including design intent, according to the level of de tail of the process information. Consequently, the designer's input overhead can be mitigated 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 implementing the Activity Chain Model is a computer sys tem for the global design which is a new design style based on collaboration between designers beyond the physical restrictions of time and space. From the results of the evaluation of the POET Knowledge Medium through design simulation, the effectiveness of the Activity Chain Model was confirmed, not only in capturing and transferring the design intent, but also in reminding the designers themselves of the design process. By using the POET Knowledge Medium, it is expected that knowledge and expertise concerning design can be shared on an organizational level, and that creative high-quality design using ideas from previous outstanding designs will be realized.