Efficient Insertion Strategy for Precision Assembly With Uncertainties Using a Passive Mechanism

This article uses a multiple compliant degree-of-freedoms (DOFs) mechanism (i.e., a spring) to facilitate compliant insertion in precision assembly and proposes an efficient insertion strategy accordingly. The addition of a spring increases the insertion compliance while resulting in the object being not directly controllable. The proposed strategy handles both vertical insertion and inclined insertion with an unknown posture according to force feedback. We investigate horizontal compliance when the spring is compressed or stretched and introduce the withdrawal process for exceptional situations by taking advantage of the insertion compliance. The inclined insertion is a process of inserting while estimating the hole posture and a radial compensation strategy is presented while not affecting the axial length of the spring. Efficient insertion planning is discussed in the presence of uncertainty caused by the spring for both insertion types. Experiments are carried out to demonstrate the validation of the proposed method.