Behavioural Study of the Force Control Loop Used in a Collaborative Robot for Sanding Materials

Abstract

The rise of collaborative robots urges the consideration of them for different industrial tasks such as sanding. In this context, the purpose of this article is to demonstrate the feasibility of using collaborative robots in processing operations, such as orbital sanding. For the demonstration, the tools and working conditions have been adjusted to the capacity of the robot. Materials with different characteristics have been selected, such as aluminium, steel, brass, wood, and plastic. An inner/outer control loop strategy has been used, complementing the robot’s motion control with an outer force control loop. After carrying out an explanatory design of experiments, it was observed that it is possible to perform the operation in all materials, without destabilising the control, with a mean force error of 0.32%. Compared with industrial robots, collaborative ones can perform the same sanding task with similar results. An important outcome is that unlike what might be thought, an increase in the applied force does not guarantee a better finish. In fact, an increase in the feed rate does not produce significant variation in the finish—less than 0.02 µm; therefore, the process is in a “saturation state” and it is possible to increase the feed rate to increase productivity.

Special Issue of the Manufacturing Engineering Society 2020 (SIMES-2020)

“…Regarding the specific contributions of the Special Issue in the journal Materials, 17 contributions about cutting-edge advances in different fields of the manufacturing engineering have been collected. In particular, these concern advances and innovations in manufacturing processes [6][7][8][9][10][11]; additive manufacturing and 3D printing [12,13]; sustainable and green manufacturing [14,15]; metrology and quality in manufacturing [16,17]; manufacturing of new materials [18]; manufacturing systems: machines, equipment and tooling [19]; robotics, mechatronics and manufacturing automation [20]; Industry 4.0 [21]; design, modeling and simulation in manufacturing engineering [22]. Figure 2 shows the main topics and their percentages in this journal.…”

“…The Special Issue collects five other works: in "Manufacturing of new materials", Chaudhari et al [18] analyze the effect of WEDM process parameters on the surface morphology of nitinol shape memory alloy; in "Manufacturing systems: machines, equipment and tooling", Olmo and Domingo [19] show EMG characterization and processing in production engineering; in "Robotics, mechatronics and manufacturing automation", Úbeda et al [20] study the behavior of the force control loop used in a collaborative robot for sanding materials [20]; in "Industry 4.0" Ramirez-Peña et al [21] make a descriptive review about the sustainability in the aerospace, naval, and automotive supply chain 4.0; in "Design, modeling and simulation in manufacturing engineering", Curto-Cárdenas et al [22] present a paper about the cold expansion process with multiple balls-numerical simulation and comparison with single ball and tapered mandrels.…”