Sensor‐less insertion strategy for an eccentric peg in a hole of the crankshaft and bearing assembly

Abstract

PurposeThe purpose of this paper is to give a novel sensor‐less manipulation strategy for the high‐precision assembly of an eccentric peg into a hole.Design/methodology/approachBased on the authors' previous work on the attractive region, this paper proposes the sensorless eccentric peg‐hole insertion strategy. The analysis is based on the visible strategic behaviors by decomposing the high‐dimensional configuration space of the eccentric peg‐hole into two low dimensional configuration subspaces. Then, the robotic manipulations can be designed in the configuration subspaces. Finally, a typical industry application, fitting an eccentric crankshaft into a bearing hole of the automotive air‐conditioners, is used to validate the presented strategy.FindingsThe attractive region constructed in the configuration space has been applied to guide the robotic manipulations, such as, the locating and the insertion.Practical implicationsThe designed robotic assembly system without using force sensor or flexible wrist has an advantage in terms of expense and durability for the automotive air‐conditioners manufacturing industry.Originality/valueMost previous work on sensorless manipulation strategy has concentrated on inserting a symmetric peg into a hole. However, for the assembly of an eccentric peg into a hole, the robotic manipulations should be explored in a high‐dimensional configuration space as the six‐DOFs of the eccentric peg. In this paper, the decomposition method of the high‐dimensional configuration space would make the system analysis visible; then, the assembly strategy can be easily designed in the two subspaces.