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

Rodrigo Pérez Ubeda,Santiago C Gutiérrez Rubert,Ranko Zotovic Stanisic,Ángel Perles Ivars

doi:10.3390/ma14010067

Rodrigo Pérez Ubeda, Santiago C Gutiérrez Rubert + Show 2 more

Open Access

https://doi.org/10.3390/ma14010067

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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.

Highlights

Surface finishing operations such as polishing and sanding play an important role within industry
The number of lower peaks is greater than the number of upper peaks; this is related to the measured values of the force since their mean values are less than the value of the reference force
The capability to perform a sanding process with a collaborative robot has been demonstrated through various experiments on different materials

Summary

Introduction

Surface finishing operations such as polishing and sanding play an important role within industry. These operations are performed with an aesthetic purpose and for functional reasons. The main drawback of these operations is that they have been commonly carried out manually, which makes them expensive and dependent on operator skill. They are time-consuming and prone to errors [1,2]. Improvements in time efficiency and surface quality are the main objectives for this process [3]

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