digital twin thread

In the digital twin paradigm, digital thread (Digital Thread) is an easily confusing concept. It has been mistranslated, misunderstood and misused by many people. In fact, digital threads come from the field of open architecture computers and borrow related concepts. Threads are widely used in computer systems. In addition to threads, there are also concepts such as Bus and Process. Some books will also mention concepts such as Job and Task. However, threads are a unique concept in the computer field. An important concept that became a key foundation for multitasking in computer processors and operating systems. An analysis of several related concepts in computer systems is shown in the table

Some people in China translate digital threads as "digital threads" or "digital clues", etc., which are very different from the Chinese translations of existing concepts in the computer field, and even confuse buses and threads together. This is a problem for industry professionals in the field of digital twins. Borrowing open architecture computer research results has brought many inconveniences. If the "digital thread" is equivalent to the "bus" in computer architecture, then the relevant data needs to share the channel. In fact, when industry insiders talk about the "digital thread", they generally have a similar meaning, which is obviously not conducive to the widespread use of digital threads. application.

The Industry 4.0 Research Institute conducted a detailed analysis of digital twins and digital threads, and designed a complete digital twin paradigm system. Digital thread borrows the concept from the computer system. Although it has been given a new meaning, the basic meaning has not changed, which is to achieve the purpose of data exchange.

As an analogy, a digital twin in a narrow sense is equivalent to a combination of computer hardware and BIOS. However, to make better use of a digital twin, you need something similar to a computer operating system. This is the digital thread, which maintains The purpose of digital twin data exchange order, and more extensive applications require a digital twin platform to achieve.
Digital thread was proposed by the U.S. Air Force and related defense suppliers. This chapter will provide a more systematic introduction to related concepts and applications so that readers can better understand this important concept and form a more comprehensive understanding of digital twin technology, thereby facilitating Academics can further develop research, while entrepreneurs can more easily apply it in practice.

The evolution of the digital thread

Lockheed Martin is a U.S. defense supplier. From the perspective of business types, it serves all branches of U.S. defense and is the main supplier of the U.S. Air Force. The F-22 and F-35 are the main U.S. Air Force aircraft it participates in the construction of. type. Through the development of large-scale equipment, Lockheed Martin has accumulated a large amount of technology and experience. At the same time, it has also cultivated a group of defense equipment elites, including senior researcher Don Kinard, who in 2010 In September 2018, he wrote the article "Digital Thread: The Key to the F-35 Joint Fighter's Responsibility," which gave a relatively complete and systematic introduction to digital thread.

Don Kinard graduated from Trinity University and Texas A&M University with a PhD in physical chemistry of polymers. He has worked at Lockheed Martin for 36 years, including 18 years of experience on the F-22, responsible for engineering and manufacturing. He later participated in the F-35 project and has now worked for 18 years, responsible for the digitalization of the aviation sector. Transformation work. Therefore, he has experience in materials and structures, manufacturing technology, manufacturing systems and production management. In addition, when he introduced himself, he also specifically pointed out that he had experience in "digital thread integration".
On May 15, 2010, the U.S. Air Force released "Technology Horizon: U.S. Air Force Science and Technology Vision (2010-2030)". The word "thread" did not appear in the report; in the "U.S. Air Force Science and Technology Plan" released by the U.S. Air Force in 2011 , the "Digital Design Thread" appeared. On June 21, 2013, the U.S. Air Force released "Global Horizon: U.S. Air Force Global Science and Technology Vision". The report is in the "Game Changers" section of the "Mission Support" and "Manufacturing and Materials" sections. Digital threads and digital twins are clearly proposed.

In the "Appendix" report released at the same time as the "Global Horizon: U.S. Air Force Global Science and Technology Vision" released by the U.S. Air Force in 2013, the digital thread was also introduced a lot, with a total of 21 mentions. The Industry 4.0 Research Institute carefully analyzed the U.S. Air Force’s understanding of digital threads. It is mainly divided into two types: First, it regards digital threads as a design capability. This is because the relevant data of products and systems driven by design innovation should be determined at the time of design. , so it makes sense to use it as a single data source; secondly, for the needs of procurement management, the U.S. Air Force uses it as a technical capability for data exchange, including data management of the entire process from materials, design, processing to manufacturing. , which can achieve refined management of projects and control the aimless growth of procurement costs.

Since the U.S. industry began to pay attention to digital twins in 2017, Don Kinard has become the target of invitations to major forums. He realized that digital threads have become his iconic vocabulary, so he strengthened the concept of digital twins and digital threads. Research, gradually linking digital threads with advanced manufacturing and Industry 4.0. According to the author's observation, his main speech topics in recent years have centered around digital threads. For example, he shared "Advanced Manufacturing, Digital Threads and Industry 4.0" for INCOSE, detailing the reasons for the emergence and development trends of digital threads.

In his speech, Don Kinard divided the evolution of digital threads into four stages, namely: physical models bring digital thread development, digital threads drive automation, integrate data into the production process and realize dynamic twins of construction configurations , as shown in Figure 4-1, reflects the trend of continuous and in-depth integration of digital threads with the defense equipment manufacturing process.

When looking forward to the development trend of digital threads, Don Kinard calls the so-called Industry 4.0 the fifth stage. He believes that the information system data in the two domains of the enterprise's internal production site and operation management are isolated and not connected. At the same time, if the data exchange and sharing of various systems are realized, then this stage can be called the fifth stage of the digital thread.
The four stages of digital thread evolution described by Don Kinard are explained below.

Phase One: Physical Models Bring Digital Thread Development

It starts with creating physical models, then integrates various physical models, designs electronic prototypes, and achieves digital verification. Then, it uses simulation software to confirm digital processes, digital factories, operation and maintenance, etc., and finally the application of hardware and software. This stage Data needs to be reused, including digital machine tools, lean production line planning, digital inspection and training, etc.

Don Kinard believes that the physical model is the starting point of all data. Through this single data source, the entire product process from design, verification, production to maintenance needs to apply this single data source. This is exactly what the digital thread has. value.

Phase Two: Digital Thread-Driven Automation

Since there is already product design data in the physical model stage, the application of these data at the production site has become an important scenario where the digital thread plays a role. Don Kinard calls the digital thread application at this stage "data automation", that is, automating production and manufacturing through data automation. This is exactly the goal that manufacturing has pursued for more than 200 years.

Of course, complete automation may be difficult to achieve, but it is a huge progress to accurately bring the data from the design stage to the production site through digital threads. Engineers at the production site can use this data to design various automation tools. Going one step further, This single data source can also be leveraged for automation at the production line, shop floor or factory level.

Phase 3: Integrating data into the production process

If the digital thread can be updated in real time, engineering data can be effectively integrated into the production process. Don Kinard cited two cases: one is the use of data fusion methods in F-35 manufacturing, and field engineers select appropriate solutions based on the needs of each screw on the fuselage surface; the other is the use of augmented reality technology, which can be used on-site and Solve equipment installation and maintenance problems remotely.
As you can imagine, if the single data source brought by digital threads cannot be applied, the mere task of finding valid data is enough to drive engineers crazy. Digital thread technology requires that various data meet certain standards and be updated in real time from the beginning. This makes it easy for engineers to obtain data when they need it. At the same time, when developing various tools, digital threads can be designed into the system. go.

Phase 4: Implementing dynamic twins of build configurations

It is not an easy task to realize the dynamic twin of production and manufacturing according to the construction requirements. The current F-35 production process is also in the exploratory stage. The difficulty lies in the development of non-contact measurement methods. Only in this way can the requirements of dynamic twins be met.
When Don Kinard introduced dynamic twins, he raised concerns about issues such as production scale, technology and economics, because to realize the digital thread application of dynamic twins, a large number of robots need to be used, and these robots also need to have high performance. Intelligence, so that they can cooperate with each other or with other devices. Judging from the current technical level, to achieve such an effect, huge resources and funds need to be invested. Whether it is economical is a question that needs to be discussed.

The digital thread evolution process mentioned above basically presents the core value of a single data source. If digital twins are implemented, digital models will exist from beginning to end, and their management and application will be truly data-driven.

Since Don Kinard proposed the application of digital thread based on his own work needs in the aviation field, its conceptual system has certain limitations. In the long run, it should be integrated into the digital twin paradigm to form an integrated technical system and be used in other applications. industry applications. Some companies that provide product life cycle management software use this to equate their products with digital threads, which greatly limits the application prospects of this concept, because many industries or fields do not use the concept of product life cycle, such as digital twin cities and Digital twin energy field.

Digital thread cannot be equated with product life cycle management. Even in manufacturing, digital thread involves data exchange at multiple stages in digital twin manufacturing, and even has the goal of data sharing, which has exceeded the capabilities of product life cycle management software. scope, the value of digital thread data exchange and sharing should be viewed from the perspective of the entire manufacturing system.