Hybrid Compliant Strategy for Multiple Peg-in-Hole Assembly in Robotic Drain Line Connection

This paper proposes a hybrid compliant strategy for multiple peg-in-hole assembly in robotic drain line connection based on a novel hybrid compliant device. A single peg-inhole assembly process is first achieved using active compliance, where gravity compensation and an admittance controller is introduced to ensure its success rate. Multiple peg-in-hole assembly is then performed using the proposed hybrid compliant device. The device first performs single peg-in-hole assembly based on the admittance controller. The adjacent peg is then assembled into the corresponding hole by rotating the device under the guidance of the manipulator. The remainder of the pegs are finally inserted into their respective holes by releasing the springs. Note that the last two steps of the assembly process are fully performed by passive compliance using the proposed device. Experiments are carried out to evaluate the performance of gravity compensation the admittance control-based single peg-in-hole assembly. The results show that the gravity compensation is accurately performed, and the single peg-in-hole assembly is achieved successfully, which further shows great practicability of the proposed strategy.