Search Strategy for Layered Peg-In-Hole Using Dual Manipulator System
Haeseong Lee, Yonghee Lee, Junheon Yoon, Jaeheung Park
AI summary
Problem
Current robotic assembly research largely ignores the layered peg-in-hole scenario involving three moving workpieces, leaving a gap in handling complex, occluded industrial tasks without specialized fixtures or vision systems.
Approach
The authors propose a dual-manipulator strategy that first aligns the peg and through-hole using a kinetic energy-optimized bi-spiral trajectory, then guides the peg into the final hole using either synchronized or compliant asynchronous control modes.
Key results
- Formal definition of the layered peg-in-hole assembly problem
- Kinetic energy-optimized bi-spiral trajectory for preliminary alignment
- 36.8% reduction in average joint power compared to traditional uni-spiral search
- 100% assembly success rate in the definitive phase using asynchronous compliant control
Why it matters
Provides a practical, sensor-free assembly solution for complex industrial components using standard dual-arm robots, reducing reliance on costly vision systems or task-specific fixtures.
Abstract
This study introduces a novel assembly, layered peg-in-hole, and suggests a search strategy. Distinct from the traditional peg-in-hole assembly, where two workpieces (i.e., peg/hole) are present, the layered peg-in-hole assembly contains three workpieces (i.e., peg, hole, and thru-hole). To handle the additional moving part, the through-hole, without relying on task-specific devices, a dual-manipulator system is preferable to a single manipulator system. However, existing research has primarily concentrated on the traditional peg-in-hole assembly regardless of the number of manipulators. In this respect, as the main contribution, a search strategy is proposed for the layered peg-in-hole assembly, which consists of two phases. In the first phase, both manipulators actively engage in the search task. In the second phase, the compliant behavior of the manipulator grasping the through-hole is advocated to assist the counterpart. Finally, the proposed search strategy is verified through the real robot experiment that replicates an industrial environment with two 7-DOF torque-controlled manipulators.