Unfastening of hexagonal headed screws by a collaborative robot

Research output: Contribution to journalAbstractpeer-review

External organisations

  • Wuhan University of Technology
  • Wuhan University of Technology
  • Ministry of Education China


Disassembly is a core procedure in remanufacturing. Disassembly is currently carried out mainly by human operators. It is important to reduce the labor content of disassembly through automation, to make remanufacturing more
economically attractive. Threaded fastener removal is one of the most difficult disassembly tasks to be fully automated. This article presents a new method developed for automating the unfastening of screws. An electric nutrunner spindle with a geared offset adapter was fitted to the end of a collaborative robot. The position of a hexagonal headed screw in a fitted stage was known only approximately, and its orientation in the hole was unknown. The robot was programmed to perform a spiral search motion to engage the tool onto the screw. A control strategy combining torque and position monitoring with active compliance was implemented. An existing robot cell was modified and utilized to demonstrate the concept and to assess the feasibility of the solution using a
turbocharger as a disassembly case study.


Original languageEnglish
Number of pages14
JournalIEEE Transactions on Automation Science and Engineering
Early online date9 Jan 2020
Publication statusE-pub ahead of print - 9 Jan 2020


  • Automated unfastening, collaborative robot, disassembly, human–robot collaboration, remanufacturing, unscrewing