Model-free Fuzzy Tightening Control for Bolt/Nut Joint Connections of Wind Turbine Hubs

Christian Deters, Emanuele Secco, Helge A. Wurdemann, Hak-Keung Lam, Lakmal Seneviratne, Kaspar Althoefer

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review

8 Citations (Scopus)


In the wind turbine manufacturing industry, the bolt-nut joint tightening process is one of the core processes in the full production chain and concerned with assembling the hub body, the pitch system and the bearing unit. This operation is currently executed manually with the aid of different tools and gauges; the main disadvantages are a relatively high degree of variability and the necessity to repeat this task several times during a production run to achieve a satisfactory, final tightening torque within a specified angle range. Moreover, the bolt tightening process includes various uncertainties such as the presence of friction forces and the use of different bolt sizes with different stiffness values which make it highly nonlinear and uncertain resulting in a challenging control problem. To facilitate the development of an effective control strategy, we study the bolt tightening process and propose 4 tightening stages, namely, bolt-nut alignment, partial and full engagement and final bolt tightening. Based on the characteristics of each stage, a fuzzy controller is designed for each stage to realize the respective control objectives. A fuzzy error detector incorporating the knowledge of each stage is proposed for early error detection, making use of the input from a torque and encoder (angular position) sensor. Errors can be detected in each stage to interrupt the process and prevent any damage to the system.
Original languageEnglish
Title of host publication2013 IEEE International Conference on Robotics and Automation (ICRA)
Number of pages7
ISBN (Print)9781467356411
Publication statusPublished - May 2013
EventIEEE International Conference on Robotics and Automation 2013 - Karlsruhe, Germany
Duration: 6 May 201310 May 2013


ConferenceIEEE International Conference on Robotics and Automation 2013


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