Control Method of Constant Force Grinding based on Active and Passive Control In recent years, bone cutting toolultrasound osteotome has been used in the treatment of spinal stenosis. However, the contact force has a great influence on its cutting performance. The cutting speed will be reduced, if the connecting force is too small or too excessive. At present, the clamping devices at the end of the surgical auxiliary robot are mostly rigid connections, which will lead to the instability of the contact force between the surgical instruments and the vertebrae and the inability to achieve efficient and safe grinding. In this paper, a flexible force stabilizer for clamping ultrasonic bone knives is designed based on activepassive combined control mode. A flexible element is added in the ending grasp device to eliminate the sudden change of the contact force. An adaptive fuzzy controller is designed outside the loop to adjust the ideal contact force between the osteotome and the lamina according to the difference with the actual contact force for realtime adjustment. Through comparison experiments, the validity and feasibility of the activepassive combined hybrid control method for the contact force control of the end of the bone knife was verified.

Modeling and Force Control of Robotic Polishing System for the Wheel Hubs Polishing is a key step in the manufacturing of wheel hubs since it will affect the appearance and performance of the wheel hubs. In this paper, a robotic polishing system is designed for the wheel hubs. To facilitate variable selection and controller design, the polishing process is firstly modeled. A roughness model considering the classic Preston material removal model is proposed. The roughness model aims at controlling the surface roughness rather than the material removal of the workpiece, which is more suitable for the robotic polishing for the wheel hubs. Then, a positionforce hybrid control framework is proposed for the robotic polishing system. To improve the performance of the force control, a threelevel rulebased adjusting method is designed and robot motion trajectory is planned based on the resolution surface of the wheel hubs. Finally, polishing experiments on the wheel hubs are fully conducted to demonstrate the effectiveness of the proposed modeling and control method of this paper.