DRAGON INNOVATION, INC. !

CLASS 10: TEST DESIGN & STRATEGY !

SEPT 8, 2014 !!!!!!!

WILLIAM DRISLANE | VP ENGINEERING | @DRAGONINNOVATE | WWW.DRAGONINNOVATION.COM

The Purpose of Testing

• Design Verification Testing à Verify that the product design is sound, that the intent of the design is achieved, and that the product is manufacturable.

• Because design represents the ultimate constraint for the performance of a product, a small number of successful tests can demonstrate a successful design.

• Production Testing à Verify that every manufactured product has been manufactured correctly, and continues to meet the design intent.

• In production, thousands or millions of products all have to be manufactured correctly.

Types of Test Conditions

• Normal Use

• Abnormal Use

• Abuse

• Life and Reliability

Types of Test Data

• There are two types of data that can be collected when you perform a test:

• Attribute Data – Go/No-Go or Pass/Fail

• Variable Data – Scalar measured quantities – voltage, pressure, etc.

• Which is more useful? Why? Which can be transformed into the other?

Test Coverage

• 100% Testing is best when it can be done

• Sometimes only a sample can be tested

• Destructive testing

• Too expensive

• Too slow

• Constructing a sample test plan – sample size depends on the level of statistical confidence required.

• Example – Manufacturing QC sampling often done using US DoD MIL-STD-105E.

Component Life Test and Redesign

• Important components are life-tested and the budget is updated.

• Testing must be realistic. Even if there are problems in this area, a weak point is almost always still a weak point.

• You must guard against the tendency to label all failures as flukes to avoid doing the right thing.

• The product is guilty until proven innocent.

System Life Testing• Component life testing is not sufficient by itself

• Systems can have problems due to interactions of components, and these problems can only be found by testing the system as a whole.

• Sometimes this effect dominates

• Software

• Electrical noise problems

• Once the components become fairly reliable, it is typically more effective to switch over to systems testing.

Maximize the Learning

• Focusing solely on passing a test can lead to ‘pencil-whipping’ the data and failing to see important problems.

• Early testing especially must focus on gaining a solid understanding of what is going on with the product.

• Once you understand the problems sufficiently well, the solutions are frequently no-brainers.