Research on hybrid force/position control method for robot peg-in-hole assembly

Abstract

Industrial robots play a crucial role in intelligent manufacturing production lines. By installing a six-dimensional force sensor at the end of the industrial robot’s wrist, a force/position control method is designed in this paper, which simplifies the teaching complexity of the assembly robot and achieves smooth assembly. Employing an admittance control strategy, the signals of external force/torque received by the robot end from the six-dimensional force sensor are used as inputs, while the position/pose deviation of the robot end serves as output, enabling drag teaching during assembly. The actual peg and hole mating process performed by the industry robot is divided into three stages: hole-searching, chamfer-entering, and inserting. By analyzing the contact force on the peg in each stage, the control parameter matrix for the assembly force/torque to posture is determined. A robot joint variable-solving algorithm is designed to dynamically adjust the motion of each axis of the robot in real-time, realizing compliant control in the presence of contact force/torque during assembly. Taking the example of parts with a peg-in-hole fit tolerance of φ25H7/g6, actual assembly experiments are conducted. The experimental results have verified the effectiveness of the control strategies for industrial robot drag teaching and parts assembly system.