Valiant Technology Ltd.

Introduction	Design	Ideas	Design & Control	Project Suggestions
Design Process	Design Brief	Evaluation	The Design	Design Review
Page 1	Page 2	Page 3	Page 4	Page 5

How can you get out of a rut in Roamer Design?


Change the basic shape.	Give the Roamer a trailer

Change the basic colour.

Make the Roamer into a body, not a head.

Design Calculations

Most designers work intuitively. Yet design, particularly engineering design, can involve mathematical, scientific or technological calculations. Good professional designers can support their intuitive flair with calculation and vice versa.

Design calculation may provide useful educational opportunities for older pupils. By providing a practical problem solving context, Roamer design can make mathematics meaningful. The simplest calculations illustrate how vital mathematicsis in modern technology and how essential the skill is to some types of designer.

Structural engineering designers are frequently involved in stress and strain calculations. However, they do develop an intuition which enables them to predict answers to very complex problems. Sometimes they estimate the size of a structural member and check its suitability by calculations. Other times they check their calculations by intuition.

Calculate the minimum sheet size from which the cardboard hopper can be made.
Calculations involving minimising material wastage are very common, even in non-technical design fields.

Roamer Crane: What length of "cable" is required?
How many 7.5o steps does the stepper motor need to take to lift a load through a height L?
These questions can be resolved by trial and error; alternatively they can be solved by calculation.

Alternative Designs

Generating Alternative Designs

It is good design practice to devise more than one Basic Design. These are evaluated to see which is the most suitable for further development. Older children should be encouraged to adopt this approach.

Appraising Basic Designs

Proposed designs should be judged on their ability to fulfil the Design Brief. During evaluation the designer will consider factors not stated explicitly in the brief. For example, a designer would automatically appraise a design on its manufacturing simplicity even if this was not stated specifically in the design brief. (Also see Design Factors).

Appraisal should be tried even by inexperienced pupils. It helps to clarify what they are expecting and make comparisons with the final design.

Teacher-designed Appraisal Sheets can prove useful for younger children.

Teacher: "Do you think your design will be easier to make than the others?"

Clare: "Yes."

Teacher: "Why?"

Clare: "Cos it uses lots of stickers and widgets. They're easy to put on."

Teacher: "What about the paper?"

Clare: "I want to paint it red. You can paint paper easy."

This transcript illustrates how teacher-led discussions can be very beneficial in helping pupils to clarify their expectations.

Transcript of appraisal discussions of a group of junior school children looking at different design ideas for a cow.

Written design briefs are useful check lists for design appraisal.

A Formal method for Appraising a design

Older children may try a formal evaluation method. The options for a Roamer Rescuer were evaluated using this approach.

Roamer Rescuer: Pick-Up Ramp Design

Appraisal criteria were considered to be:

Roamer Rescuer: Pick-Up Ramp Design
Criteria	Weighting	Score	Weighted Score	Comments
Locate Breakdown	2	1	2	Could be difficult to get boarding ramp in right place.
Pick-up breakdown	3	2	6	Simple mechanism
Drag breakdown	3	2	6	Keeping breakdown on ramp may be a problem
Programming	2	2	4	Involves Control programming
Speed of recovery	1	2	2	Locating breakdown could be slow.
Manufacture	2	3	6	Simple to make
Cost	1	3	3	Simple design = low cost
		Total	29

The design criteria are classified as to their importance:	How well the design complied with each criterion is scored:
0 - Unimportant 1 - Useful feature - Achieve if possible. 2 - Important feature. 3 - Essential feature.	0 - Does not satisfy the criterion. 1 - Moderately satisfies the criterion. 2 - Satisfies the criteria very well. 3 - Completely satisfies the criterion.

The viability of the design is calculated. The design with the highest total is selected. Any design rating 0 for any of the essential factors is automatically precluded.

Evaluation of Roamer Rescuer: Drag Line Design
Criteria	Weighting	Score	Weighted Score	Comments
Locate Breakdown	2	3	6	No precise movement required
Pick-up breakdown	3	3	9	Simple mechanism
Drag breakdown	3	3	9	Experiments show this method ofdragging works well.
Programming	2	3	6	No complex programming
Speed of recovery	1	3	3	Will be as fast as possible if route around Roamer is kept to a minimum.
Manufacture	2	3	6	Simple to make
Cost	1	3	3	Simple design = cheap cost
		Total	42

Drag Line Design

Formal appraisal of Roamer Rescue designs by pupils from King Edward VI School serves to illustrate a number of key points.

The Drag Line Design is an excellent example of an'out-of-the-rut' design solution.
Its simplicity makes it an easy winner.
If the criterion "Move the Roamer to any location" is considered essential then this design could score 0 and would be rejected.

Careful choice of ihe appraisal criteria is essential.

This technique can be hard for the inexperienced pupil. But the process of formal appraisal provides an excellent record of the pupils thinking and can be used to assess which design assumptions worked and which didn't.

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