A General Method for Autonomous Assembly of Arbitrary Parts in the Presence of Uncertainty

In this paper, we propose a novel and general method for autonomous robotic assembly of arbitrary and complex-shaped parts in the presence of 6-dimensional uncertainty. When a nominal assembly motion of the robot holding a part is stopped by contact due to uncertainty, our method finds the best estimate for the uncertainty and the contact configuration of the part based on sensed force/torque and uses that information to find a more accurate estimate of the goal configuration to guide a recovery motion of the part. It is based on a general, surface-based sphere tree representation of parts, a constrained optimization strategy to find the best estimate of the contact configuration under an uncertainty estimate, and a learned force/torque calibration model to relate computed force/torque and the sensed real force/torque. The method is applied and evaluated on different complex-shaped multi-peg-in-hole tasks. The results show that our method can achieve successful assembly with the presence of realistic 6-D uncertainties more than 10 times of the tight task clearances in terms of orientation clearance
$(< 0.015rad)$
and position clearance
$(< 1.5mm)$
, in all the test cases.