Conceptual, Embodiment and Practical Design

Question 1

When designing function structures, what are the 3 types of inputs and outputs to each function?

Answer 1

Energy
Materials
Signals

Question 2

Steps to constructing a fast diagram

Answer 2

• Start with general functions and then get progressively more specific
• Each function should be a verb and a noun (simple as possible)
• Chronologically trace through each function that must be accomplished
• Include all modes of operation (eg standby, run, cleaning, etc.)
• Avoid specifying form
• Can customise the FAST diagram, the more information that can be conveyed, the more useful the diagram

Question 3

What question does going left and right answer on a FAST diagram?

Answer 3

Right- HOW?

Left- WHY?

Question 4

3 basic rules of embodiment design

Answer 4

• Clarity - clear assignment of conceptual functions to function carriers
• Simplicity - simpler is easier to realise, but functional requirements take precedence and may demand complexity
• Safety

Question 5

5 techniques for safe design

Answer 5

• Safe life (components+interfaces designed to survive their predicted working life)
• Redundancy (components designed to take over system function in the event of a failure)
• Monitoring systems (system to predict the early signs of system failure)
• Fail-safe (demands that possible system failures must be predicted and corresponding fail-safe states)
• Protective systems (operator or environment can be protected from the consequence of failure by a protective system eg fuses, safety valves)

Question 6

Types of redundancy

Answer 6

Parallel, series, quartet, quartet cross redundancy

Question 7

What does practical design realise?

Answer 7

That the ideal order of tasks: task clarification, conceptual design, embodiment design and detail design are unlikely to be conducted in such an orderly manner, with elements of conceptual design preceding the completion of task clarification etc. (they’re intertwined processes due to iteration/rework)

Question 8

Name 5 common design principles used to help broaden the search space

Answer 8

• Occam’s razor- simplest solution often better
• Cascading errors- small errors can either cancel out or cascade into larger ones and eventually failure
• Symmetry- can lead to more efficient design
• Self principles- designs that help themselves eg self-braking, self-sealing
• Recipricosity- design errors to reverse to the mean
• Superposition- inputs from 2 or more sources will sum in a linear system
• Divide and Conquer- break down the problem into sub-problems until they become easy to solve
• Sensitivity- perform sensitivity analysis, what independent variables is the system sensitive to?
• Human action laws- average time for certain human actions taken into account
• Cognitive predictions- the time it takes to select a choice among a selection, closed loop feedback-guided interaction is slower than open loop direct recall from motor memory
• Path dependency- systems have to weigh up the cost of adopting a new system vs the eventual gain from the new system
• Value engineering- the ratio of function to cost