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.

Global VisionBased Impedance Control for Robotic Wall Polishing Wall polishing is a typical and essential procedure in the interior renovation. However, such works are mainly carried out by humans, which have the disadvantages of low efficiency, inconsistent quality, and issues of safety and health. A new visionbased impedance controller is proposed for polishing robots to automate the laborintensive works. The desired impedance model is specified as the control objective to regulate the dynamic relationship between the interaction force and the motion of the robot end effector, where the motion is measured with the vision feedback. The use of the vision feedback guarantees the performance of the robot from two aspect. First, the vision feedback from the highresolution camera ensures the accuracy of measurement of the robot end effector and hence guarantees the quality of polishing. Second, the concept of image moment is introduced such that the image Jacobian matrix is nonsingular in a global sense, which guarantees the large working range of the robot. The dynamic stability of the closedloop system is rigorously proved with Lyapunov methods, and experimental results are presented to illustrate the performance of the proposed controller.