## 1 Introduction  
Recently, innovations in the ICT (Information and Communications Technology) field have begun to rapidly change existing manufacturing methods into smart manufacturing methods or CPS (Cyber Physical Systems) [1]. These manufacturing methods can use IoT (Internet of Things) technologies and web-based services to communicate and interact with other products in a factory environment. Due to the COVID-19 pandemic, many manufacturers have come to seriously consider the problem of flexibly adjusting production according to environmental changes while promoting employee safety. Depending on the situation regarding changes in infectious diseases, the demand for certain products varies substantially by country or region. Specifically, manufacturing companies that rely on small-scale production of multiple varieties should come up with countermeasures such as quickly readjusting their production lines and educating their employees on new production manuals in line with changes in consumer demand. As telecommunities continues to increase, the need to clearly check the status of production plants online is increasing as well. For manufacturers to overcome the COVID-19 pandemic crisis, it has been stated that it is necessary to actively introduce robot automation that can promote the safety of employees and increase production efficiency, and to combine virtual convergence reality technologies such as Digital Twin and VR (Virtual Reality)/AR (Augmented Reality) technology. Although the development of Digital Twin started from the Aerospace industry, the industry which is exploring the technology the most is the manufacturing industry. Digital Twins have been described as the key enablers of Industry 4.0 and Smart Manufacturing [2; 3]. Any manufactured product goes through four main phases throughout its life cycle: design, manufacture, operation, and disposal. Smart manufacturers can leverage Digital Twins in all four phases of the product [4; 5]. During the design phase, Digital Twin allows the designers to verify their product design virtually, which enables them to test different iterations of the product and choose the best one. An example of this is the car manufacturer Maserati, which used Digital Twin for optimizing car body aerodynamics using wind tunnel tests virtually, which are elaborate and expensive otherwise. Unlike traditional bike designing methods, which are based on the designers' knowledge and experience, the Digital Twin of a bicycle constantly collects the data from the physical space, which could be compared, analyzed, and used for designing or redesigning next-generation bicycles. With customer reviews and usage habits, designers can get a better understanding of customer requirements, which can be translated into better and improved features. Capturing customer preferences via a Digital Twin lets businesses know about the market trends which can be integrated with the customer usage data to see the effects on product performance. This allows businesses to take design-decisions and incorporate them in an informed way, thus making the process of integrating the customer feedback into the product to deliver customized products easier [6]. One of the most developed directions in manufacturing, especially in the scope of Industry 4.0, is the robotization and automatization of the production lines [7]. Digital Twin is playing a crucial role in this integration, as industrial robots are being programmed with mainly three methods, which are closely related to the twinning of the manufacturing equipment.