A Series-Parallel Hybrid Pelvic Fracture Reduction Surgical Robotic System Based on Novel 6-DOF Force Amplification Mechanism

Robot-assisted closed reduction surgery is recognized as the optimal approach for pelvic fractures. However, existing surgical robotic systems often lack the necessary output force to overcome soft tissue tension. To address this limitation, we propose a novel surgical robotic system to deliver high output force with required workspace. Our approach includes the design of a 6-DOF parallel mechanism that utilizes the lever principle for force amplification. The distribution laws of its effective workspace and force amplification gain coefficient are investigated. Additionally, a series-parallel hybrid surgical robot system is developed, which demonstrates the amplification effect on the output force through the force amplification mechanism. To ensure smooth operation of the system, a comprehensive surgical operation framework isdevised that encompasses target pose planning, reduction path planning, real-time intraoperative navigation and control. Modeling experiments show promising results, with an average reduction accuracy of 0.31 mm and 0.24° under no load, and 1.03 mm and 0.34° under loads ranging from 0N to 475N. These findings highlight the effectiveness of our proposed force amplification mechanism in achieving substantial output force amplification while alleviating the surgeon's burden. Moreover, our robotic system demonstrates the capability to achieve precise pelvic fracture reduction, significantly enhancing surgical outcomes.