A dual-arm robotic cooperative framework for multiple peg-in-hole assembly of large objects

Single peg-in-hole assembly of small objects has been researched extensively. However, these studies limit applicability to multiple peg-in-hole assembly of large objects, due to the complex contact state, and the large size and weight of the objects. To address these challenges, this paper proposes a dual-arm cooperative multiple peg-in-hole assembly framework (DAC-MPiH) for large objects, leveraging the capabilities of dual robots to manage larger, heavier objects. The DAC-MPiH framework comprises three key components: dual-arm force/position coordination, external force/torque estimation, and an eight-stage assembly strategy. The proposed framework integrates a compliant dynamical system (CDS) into both inner and outer control loops, ensuring robust force/position coordination and stable manipulation at the object level. The framework introduces an object parameter estimation method based on a virtual center of mass and least squares to enhance the accuracy of external force/torque estimation. The assembly strategy includes four preparation stages and four assembly stages, utilizing a CDS-based variable impedance and variable reference force controller for stable adjusting, and a hybrid force/position controller for efficient rotating. Experiments were conducted on a dual-arm robotic platform, and the results demonstrate the effectiveness of the proposed method in achieving stable and efficient multiple peg-in-hole assembly of large objects.