Teknillinen tiedekunta, 2017
Sähkö- ja energiatekniikan koulutusohjelma (DI)
Lean Six Sigma is used by many software development organizations to identify problems in processes and find solutions for the identified problems. By improving software development and testing processes customers will have higher quality software and products. Inefficient processes can lead to a post-production software defects that will cause loss of money and customer satisfaction. DMAIC (define, measure, analyse, improve and control) is a Lean Six Sigma method that can be thought as a problem solving roadmap introducing different tools to achieve process improvements.
Based on that method this thesis studies ways how to improve the testing process of Ethernet-based fieldbuses in Danfoss Drives so that no fieldbus defects reach a customer site. Communication protocols, also called as fieldbuses, ensure that a frequency converter integrates seamlessly into customer system.
Ethernet-based fieldbuses cause most of the post-production defects – those defects which are reported by the end user after product is released to market. Define phase starts by narrowing the main subject of the thesis which is Ethernet-based fieldbuses because they are main reason for the customer complaints. Measure phase includes gathering data from defect reporting systems and testing management systems. Analysis of the measured data informs that almost 20 percent of defects are reported by an end user. Further investigation shows that almost half of those post-production defects should have been found in functional tests. Functional tests are seen inefficient due to limited test case coverage and test case effectiveness, limitations in test specifications and test systems.
The outcome of this thesis was a fieldbus testing development plan based on the potential problem analysis introduced by the Lean Six Sigma DMAIC. All the potential problems of every testing types are identified, the possible causes are listed, severity and occurrence of the problem determined and lastly preventive actions suggested. The potential problem analysis can be used to improve the fieldbus testing process and eliminate all the postproduction defects which can lead to customer disaffection and loss of money.
Ethernet, fieldbus, frequency converter, software testing