Analysis and assessment of robotic belt grinding mechanisms by force modeling and force control experiments

2018 ◽  
Vol 120 ◽  
pp. 93-98 ◽  
Author(s):  
Dahu Zhu ◽  
Xiaohu Xu ◽  
Zeyuan Yang ◽  
Kejia Zhuang ◽  
Sijie Yan ◽  
...  
Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1635 ◽  
Author(s):  
Tie Zhang ◽  
Ye Yu ◽  
Yanbiao Zou

To improve the processing quality and efficiency of robotic belt grinding, an adaptive sliding-mode iterative constant-force control method for a 6-DOF robotic belt grinding platform is proposed based on a one-dimension force sensor. In the investigation, first, the relationship between the normal and the tangential forces of the grinding contact force is revealed, and a simplified grinding force mapping relationship is presented for the application to one-dimension force sensors. Next, the relationship between the deformation and the grinding depth during the grinding is discussed, and a deformation-based dynamic model describing robotic belt grinding is established. Then, aiming at an application scene of robot belt grinding, an adaptive iterative learning method is put forward, which is combined with sliding mode control to overcome the uncertainty of the grinding force and improve the stability of the control system. Finally, some experiments were carried out and the results show that, after ten times iterations, the grinding force fluctuation becomes less than 2N, the mean value, standard deviation and variance of the grinding force error’s absolute value all significantly decrease, and that the surface quality of the machined parts significantly improves. All these demonstrate that the proposed force control method is effective and that the proposed algorithm is fast in convergence and strong in adaptability.


2019 ◽  
Vol 2019 ◽  
pp. 1-19
Author(s):  
Tie Zhang ◽  
Xiaohong Liang ◽  
Ye Yu ◽  
Bin Zhang

The angular variation of the joints may be large, and collision between workpieces and tools may occur in robotic grinding. Therefore, this paper proposes an optimal robotic grinding path search algorithm based on the recursive method. The algorithm is optimized by changing the position of the tool coordinate system on the belt wheel; thus, the pose of the robot during grinding is adjusted. First, the position adjustment formula of the tool coordinate system is proposed, and a coordinate plane is established to describe the grinding path of the robot based on the position adjustment formula. Second, the ordinate value of this coordinate plane is dispersed to obtain the search field of the optimal robotic grinding path search algorithm. Third, an optimal robotic grinding path search algorithm is proposed based on the recursive method and single-step search process. Finally, the algorithm is implemented on the V-REP platform. Robotic grinding paths for V-shaped workpieces and S-shaped workpieces are generated using this algorithm, and a grinding experiment is performed. The experimental results show that the robotic grinding paths generated by this algorithm can smoothly complete grinding operations and feature a smaller angular variation of the joint than other methods and no collision.


Author(s):  
Guohong Xie ◽  
Ji Zhao ◽  
Xin Wang ◽  
Huan Liu ◽  
Yan Mu ◽  
...  

In the abrasive belt grinding process, there are factors affecting the machining stability, efficiency, and quality. Based on the analysis of the grinding process, the normal force in the contact area between the abrasive belt and the workpiece is a major factor. By comparing constant force and non-constant force grinding, the results imply that keeping the grinding force constant will achieve desired material removal and better surface quality. The phenomenon of over- and under-cutting of the workpieces can also be avoided by a constant normal force. In this article, a controllable and flexible belt grinding mechanism accompanied with a mechanical decoupling control strategy is built and tested. Afterward, a detailed comparison is made between the traditional force-position coupling system and the proposed decoupling control system. The proposed control system suppresses the interference between the position and force control systems. The contact force is directly measured and controlled without detecting the position of other components in the tool system. The complexity of the control system is thereby reduced. Finally, several grinding experiments are carried out. The standard deviation and coefficient of variation of the measured normal force are kept within 0.25 and 0.02, respectively. The experiment results reveal that the mechanical decoupling system performs well in force control compared with the traditional force-position coupling system. In addition, the surface roughness Ra < 0.4 μm, the surface quality of the workpiece is improved significantly with the constant force controller.


2019 ◽  
Vol 32 (10) ◽  
pp. 2368-2382 ◽  
Author(s):  
Xiaohu XU ◽  
Dahu ZHU ◽  
Haiyang ZHANG ◽  
Sijie YAN ◽  
Han DING

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