Research and consulting company Gartner gives a very brief definition: A digital duplicate is a digital representation of a real object or system.
The extended definition may be as follows:
Digital Twin is a software analog of a physical device that simulates the internal processes, technical characteristics, and behavior of a real object under the influence of interference and the environment. An important feature of the digital duplicate is that the task of its input effects uses information from the sensors of a real device running in parallel. Work is possible both online and offline. Then it is possible to compare the information of virtual sensors of the digital duplicate with the sensors of the real device, to identify anomalies and their causes.
Installation of sensors on a real device is carried out in the process of implementation of industrial Internet of Things (IIoT) technologies at the enterprise.
Without the creation of digital product duplicates, it is impossible to implement modern PLM technology (Product Lifecycle Management). IIoT and PLM are integral attributes of the "smart factory". Its characteristic feature is the formation and use of a digital model of material flows, ie. The digital double is no longer a separate product, but a production system. All the above technologies are approaches to the implementation of the concept of the Fourth Industrial Revolution (Industry 4.0). If the traditional industry achieves the required characteristics of the product through numerous field tests, then Industry 4.0 is tasked with conducting multiple tests using a digital duplicate, and field tests to be conducted from the first time.3
The digital duplicate of the product includes:
- Geometric and structural model of the object.
- A set of calculated data of parts, assemblies, and products in general.
- Mathematical models that describe all the physical processes occurring in the product.
- Information on technological processes of manufacturing and assembly of individual elements and the product as a whole.
- Product life cycle management system.
- The digital duplicate is used at all stages of the product life cycle, including design, production, operation, and disposal.
- At the stage of sketch design: variants of the computer model of the product which is developed for estimation and a choice of possible technical decisions are created.
At the stage of technical design: the option selected at the previous stage is finalized and refined using element models. The resulting product model allows you to take into account and optimize the interaction of all elements, taking into account the modes of operation and environmental influences, it can already be called a digital counterpart of the product under development.
At the manufacturing stage: the developed model helps to determine the necessary manufacturing tolerances to achieve the required characteristics and ensure a trouble-free operation of the product throughout its service life, and also allows you to quickly identify the causes of malfunctions in the testing process.
At the stage of operation: the digital duplicate model can be refined and used to implement feedback in order to make adjustments in the development and manufacture of products, diagnostics, and prediction of faults, increase efficiency, to identify new consumer demands.
Classification of product duplicates:
- Digital prototype duplicates (DTP). The DTP duplicate contains the information needed to describe and create physical versions of product instances. This information includes geometric and structural models, technical requirements and conditions; cost model, the calculation (design), and technological model of the product. DTP-duplicate can be considered a conditionally constant virtual model of the product.
- Digital duplicate instances (Digital Twin Instance, DTI). DTI duplicates of a product description a specific physical instance of the product to which the duplicate remains associated throughout its life. Duplicates of this type are created on the basis of DTP-duplicate and additionally contain production and operational models, which include the history of product manufacturing, use of materials and components, as well as statistics of failures, repairs, replacement of components and units, etc. Thus, the DTI-duplicate of the product is subject to change in accordance with changes in the physical instance during its operation.
- Aggregate duplicates (Digital Twin Aggregate, DTA). Product DTAs are defined as an information system for managing physical instances of a product family that has access to all of their digital counterparts.
Classification of production system duplicates:
- Digital duplicate of the entire production system (PS).
- Digital duplicate production line.
- Digital duplicate of a specific asset in a production line.