Improving robustness of a PID-controlled measurement system through Design of Experiments : A DMAIC case study at Atlas Copco BLM

• Main Authors: Siljeström Hansson, Eira, Hellström, Emil
• Format: Others
• Language: English
• Published: Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle 2020
• Subjects: Robustness; Design of Experiments; PID-controller; Control system; Measurement system; Probability Theory and Statistics; Sannolikhetsteori och statistik; Reliability and Maintenance; Tillförlitlighets- och kvalitetsteknik
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79557

Companies within the manufacturing industry are often aiming to increase productivity and simultaneously maintain the quality of their products. To achieve higher productivity and quality it is imperative to have tools with a high speed and accuracy. Atlas Copco BLM's STbench is a measurement system which enables manufacturers to validate their tools during different situations. The purpose of this case study was to improve the robustness of the STbench so it would operate well during situations with both low and high tool speed. To define and investigate how to improve the STbench, a modified DMAIC-approach was used. During the investigation it was found that the area with the largest improvement possibilities was the STbench's PID-controllers. Design of Experiments was used as the method to optimize the P- and I-element of the PID-controllers; hence, increase the robustness. The optimal settings could improve the robustness of the STbench with approximately 50%, but the result has not been verified. This case study presents results that can increase the robustness of the STbench; thus answering the purpose. Furthermore, this master thesis presents several revelations regarding using experimental plans while optimizing control systems, an area that has not been extensively investigated in previous literature.