Title: Haptics of Screwing and Unscrewing for its Application in Smart Factories for Disassembly,
Abstract: Reconstruction of skilled humans sensation and control system often leads to
a development of robust control for the robots. We are developing an unscrewing
robot for the automated disassembly which requires a comprehensive control
system, but unscrewing experiments with robots are often limited to several
conditions. On the contrary, humans typically have a broad range of screwing
experiences and sensations throughout their lives, and we conducted an
experiment to find these haptic patterns. Results show that people apply axial
force to the screws to avoid screwdriver slippage (cam-outs), which is one of
the key problems during screwing and unscrewing, and this axial force is
proportional to the torque which is required for screwing. We have found that
type of the screw head influences the amount of axial force applied. Using this
knowledge an unscrewing robot for the smart disassembly factory RecyBot is
developed, and experiments confirm the optimality of the strategy, used by
humans. Finally, a methodology for robust unscrewing algorithm design is
presented as a generalization of the findings. It can seriously speed up the
development of the screwing and unscrewing robots and tools.