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Design Schematics

Design Schematics is a project intended to create a diagrammatic language for the uniform representation of non-graphical product and design information with particular focus to the early stages of design processes.

The early stages of design include: requirements analysis and specification, concept design and evaluation, systems design, and product architecture development. Design Schematics are based on concept maps.

General Concepts

A design schematic is a 2D hypergraph of labelled nodes connected by (possibly) labelled links.

  • A link is a directed arc, anchored to nodes.
  • Links may be one-to-one, one-to-many, or many-to-one. Many-to-many links are not allowed.
  • The link can be labelled. The label appears usually near the midpoint of the link.
  • For hyperarcs (e.g. one-to-many links), the label is placed at the merging point of the multiple heads or tails.
  • A link is always directed to/from the geometric centre of a node (like CmapTools). Each link has two such points, called roots.
  • The label of a link is said to indicate its type. All unlabelled links are of a single null type. Anchor labels do not contribute to the type of a link.
  • All links of the same type are to enter or exit nodes from the same (general) direction.
  • Links are either vertical or horizontal. They may be segmented - having both horizontal and vertical elements - in which case the corners are visibly rounded.
    • This helps prevent visualization difficulties of links cross one another in a diagram.
    • It also helps follow links from one node to another when links split or merge (the on-ramp/off-ramp analogy).


  • An anchor is where a link appears to connect to a node, at the node's outer edge. An anchor is not a root.
  • A link connecting two nodes has two anchors, one at each end. The anchors can be labelled. The labels appear outside the node, but near where the link touches the node.
  • Anchor points can be important locations for information, like cardinality constraints, as in the example below.

A simple example of the use of anchors to specify constraints on relationships.


  • A node is a geometric shape with an optional text note within it to describe it. Colour, shape, and border size can be used to indicate specific characteristics of nodes.
  • Node text must not include boolean operators (and, or, not). Negations should be phrased as inverse assertions (e.g. “cannot be heavy” should be written as “must be light”.)

Significance of Nodes

  • Some nodes may be more important than others. The importance of a node is rated on a three-point scale.


A node of extreme importance is denoted by a thick line border and bold font.


A node of moderate importance is denoted by a normal thickness line border and normal font.


A node of low importance is denoted by no line border at all and normal font.

Kinds of Design Schematics

Usage Schematic

A usage schematic (US) captures the operation of a product from the user's point of view. It is possible to represent a product with a US even before design has begun, with only the knowledge of what need exists among users.

Personas: a persona is an imaginary, hypothetical user, constructed by the designer to help imagine how users will (inter)act with a product.

Product Requirements Schematic

A product requirements schematic (PRS) is a DS that captures the design problem and the results of reasoning from that problem. It incorporates aspects of Axiomatic Design [Suh90], Pugh's product design specifications [Pug91] and Dym's objective trees [DL00], but extends them in certain ways.

Function Schematic

To be written…

Product Architecture Schematic

To be written…

Open Issues

  • TODO Try reproducing some FADs (e.g., [AEO11]) as DSs and compare them.
  • usage scenarios are extremely similar to pert, cpm, and gantt charts.
  • “process & instrumentation diagram” for configuration of components in piping systems; same level as modelica.
  • What about taking a DS and redisplaying nodes as links and links as nodes. This could possibly highlight features of the topology that are otherwise hidden.
  • clusters of nodes that are highly interrelated to each other when compared to other nodes in same diagram probably should be one level down in detail and should be replaced by a single node.

Research Issues

Jan 2007: Sandun Weerasinghe came up with this idea:

  • We were trying to see a way to incorporate the DOOR into the system but we were having trouble with it because the person doesn't really interact with the door. Instead of making the line enter the DOOR system from one end and then a new line exit the DOOR to the CAB, why don't we just make it pass over it. This way it doesn't imply an interaction with the DOOR just that is passes through it.


  • Junctions between links & nodes are important for cardinality & other constraints.
    • Junctions should be labelled too.
  • Rounded corners on zigzag links are important.
  • Google CZweb and CZtalk (sfu research projects)
  • Leake, D.B., and D.C. Wilson (2001), A case-based framework for interactive capture and reuse of design knowledge, Applied Intelligence, Vol. 14, No. 1, pp. 77-94.
  • Review impact of DRed [BAW04] on DS.
  • From Gero's keynote at Design2004: “What you're looking for affects what you see.”
    • Also: “The tools we've built (e.g. CAD) were built as if people don't matter.”
    • His paper provides some justification for DS and motivation for diagramming
    • the agents Gero uses seem similar to the dynamic force work done at CalPoly in the 1980's.

See Also


[Pug91]. S. Pugh. 1991. Total design: integrated methods for successful product engineering. Addison-Wesley, England.
[DL00]. C. L. Dym and P. Little. 2000. Engineering Design: A Project-Based Introduction. Wiley and Sons, New York.
[AEO11]. M. Aurisicchio, N.L. Eng, J.C. Ortiz, P.N.R. Childs, and R.H. Bracewell. 2011. On the function of products. Intl Conf on Engineering Design. The Design Society. (link)
[BAW04]. R.H. Bracewell, S. Ahmed and K.M. Wallace. 2004. DRed and design folders, a way of capturing, storing and passing on, knowledge generated during design projects. Paper DETC2004-57165, Proc ASME Design Engineering Technical Conferences; ASME, New York
research/design_schematics.txt · Last modified: 2020.03.12 13:30 (external edit)