Path Planning under Force Control in Robotic Polishing of the Complex Curved Surfaces

Abstract

Surface polishing is required in many manufacturing sectors. Currently, it demands a large amount of manual work, which is time-consuming, error-prone, and costly. Additionally, it creates hazards for the workers as it may result in many deadly respiratory diseases. Robotic polishing is the solution to these problems. It can improve productivity, eliminate the defects, and provides consistent product quality. In this paper, an effective approach is presented for the robotic polishing of the complex curved surfaces. The key part of the presented method is the tool path planning with controlled force and polishing parameters optimization evaluated using design of experiments (DOE). The tool path planning is aimed at improving the surface quality and the contact area per path. The constraints of joint limits and productivity are also considered. Moreover, its jerk avoidance strategy allows the robot to move swiftly while ensuring a smooth trajectory. The presented method is verified for the polishing of an eyeglass frame. A considerable improvement of 90% on the average roughness is achieved with the maximum acceptable roughness set at 0.02 µm. The polishing operation takes just 79 secs and the average glossiness of 76 G is achieved on the final product along with the successful elimination of scratches on the surface.

Optimization of the Polishing Efficiency and Torque by Using Taguchi Method and ANOVA in Robotic Polishing

“…This interaction can be optimized by controlling the gripper's rotational friction or moment of inertia (it is the amount of torque required to rotate a rigid body about its rotational axis). Moment of inertia depends on the mass of the body as I = mr 2 , where m is mass and r is the distance from the pivoted point. Therefore, the rotational friction of the gripper can be control by adding friction to the axil or by adding the mass to the gripper.…”

“…The surface roughness before and after the experiment are measured to calculate ∆R a . Polishing efficiency (PE) is calculated as [2,17]…”

“…The output of this process is a smooth surface which can be characterized by plenty of parameters such as lay, surface roughness, and waviness. Many industries are using surface roughness and glossiness as the judgment factor to achieve smooth surfaces [1,2]. However, surface roughness is the most adopted parameter to quantify the surface finish [3][4][5][6].…”

“…Such methods include improvising of the tool path planning [21][22][23][24], controlled interaction between tool and surface [25][26][27], and the design of new polishing tools for specific or general type workpieces [28][29][30]. However, the optimization of parameters remains a very useful technique that can be implemented together with all these above-mentioned techniques to improve the automated polishing process [2].…”

Robotic Sanding of Wooden Bowls with Hybrid Force/Position Impedance Control

“…An alternative method for the robotic polishing of complex curved surfaces is known as the top down approach. This approach was studied by Mohsin et al [7] who used an articulated robot for the polishing of eyeglass frames. In this method, the robot holds the workpiece and the polishing disc is fixed onto a base.…”