Robotic assembly of threaded fasteners in a non-structured environment

Abstract

Over the past two decades, a major part of the manufacturing and assembly market has been driven by the increasing demand for customised products. This has created the need for smaller batch sizes, shorter production times, lower costs, and the flexibility to produce families of products-or to assemble different parts-with the same sets of equipment. Consequently, manufacturing companies have deployed various automation systems and production strategies to improve their resource efficiency and move towards right-first-time production. Threaded fastening operations are widely used in assembly and are typically time-consuming and costly. In high-volume production, fastening operations are commonly automated using jigs, fixtures, and semi-automated tools. However, in low-volume, high-value manufacturing, fastening operations are carried out manually by skilled workers. The existing approaches are found to be less flexible and robust for performing assembly in a less structured industrial environment. This motivated the development of a flexible solution, which does not require fixtures and is adaptable to variation in part locations and lighting conditions. As a part of this research, a novel 3D threaded hole detection and a fast bolt detection algorithms are proposed and reported in this article, which offer substantial enhancement to the accuracy, repeatability, and the speed of the processes in comparison with the existing methods. Hence, the proposed method is more suitable for industrial applications. The development of an automated bolt fastening demonstrator is also described in this article to test and validate the proposed identification algorithms on complex components located in 3D space.

Research on Assembly Method of Threaded Fasteners Based on Visual and Force Information

“…Vision-based control methods are widely used in precision assembly systems. They are divided into three types, including position-based [21][22][23][24], image-based and hybrid schemes [25,26]. How to accurately estimate the orientation of small components is a major issue that needs to be explored in position-based methods.…”

A variability taxonomy to support automation decision-making for manufacturing processes

“…A case study of automated fasteners assembly in a non-structured environment is used to illustrate the application of the proposed taxonomy. Fastening is a relatively simple assembly process for a human operator to perform, but it is a very complex process to automate (Dharmara et al 2018).…”

“…Non-structured threaded fastener assembly(Dharmara et al 2018), licensed under http://creativecommons.org/licenses/by/4.0/.…”

“…Process involved in automated non-structured assembly solution(Dharmara et al 2018), licensed under http://creativecommons.org/licenses/by/4.0/.Table 8. Summary of level of automation suggested for fastener assembly process.…”

Dual-Arm Peg-in-Hole Assembly Using DNN with Double Force/Torque Sensor

“…Due to rapid changes in production demand and to product changes, new challenges have arisen in the manufacturing of products, a trend that has increased throughout the years and has affected most of the industry. Therefore, more robots that work in an unstructured environment for assembly tasks will be required in factories, where fixtureless operations could be executed, giving high flexibility to the production processes [1].…”