Search trajectory with twisting motion for dual peg-in-hole assembly

This paper proposes a search trajectory for a dual peg-in-hole assembly in the presence of uncertainty. To assemble a dual peg into a dual hole, the peg should be guided to the hole by coinciding with both position and orientation. Regarding this requirement, the trajectory of the dual peg is designed by the following new concepts: insertion guarantee region and hole insertion condition. First, the insertion guarantee region is a three-dimensional region based on the clearance between the dual peg and hole, which serves as the goal for the trajectory. Second, the trajectory is designed to satisfy the hole insertion condition, which is a geometric constraint. In this respect, the trajectory has distinct advantages of robust search performance and feasibility of implementation regardless of the shape of the components. The performance of the trajectory was experimentally verified using a 7-degree-of-freedom torque-controlled manipulator, and 100% success rate was reported in the guidance of the peg into the hole.