# Value Creation with Digital Twins: Application-Oriented Conceptual Framework and Case Study
## 4 Application-Oriented Digital Twin Framework
### Role of Digital Twins  
The following sections take a closer look at the role of DTs. The focus is on their function as the connecting element of the product management levels and their generations on the time axis. **Product management levels--**To enable the full potential of DT in product management, it is necessary to distinguish different abstractions or meta-levels of PLM integration. Even though most authors, especially in the field of PLM, only differentiate instance and type (e.g., [42; 44], some authors started to distinguish a third meta-level [11; 15; 20; 43; 83; 84], referred to as \"portfolio\" in our framework (see Figure 8)). The different levels of product management are connected via several learning, feedback, and validation loops to exchange valuable data [43]. The DT of an instance is directly interconnected to the real-world counterpart and represents a bidirectional reflection from the expected digital world derived from the type and the real world observed from the instance. The DT of the instance mainly fulfills three different functions that can be described as follows, following [PERSON] and [PERSON] [56] and [PERSON] et al. [20]:  
* To integrate various data types from the real-world counterpart to map its state. * To exist and co-evolve along the life cycle of the real-world counterpart to accumulate knowledge about it. * To optimize the real-world counterpart based on variance analyses with the digital model. To fulfill the third function, the DT instance must reflect the expectations on how the real-world counterpart ought to be structured, function, behave, interact with customers and respond to uncertainties. These expectations are derived from the type referred to as a blueprint from which the instances are derived. It is the offering presented on the market and includes all data needed to promote, sell, build, operate, and servitize [85; 86], and recycle product instances. Examples of data describing a product type are requirements, BoMs, operation plans, manufacturing methods, and recycling instructions. Furthermore, configuration knowledge for the sales process or instructions and tools to fulfill a service are typical items described in a typed dataset [42], while the definition of types is continuously changed and improved, the instances follow their life cycle and might or might not be affected by changes in their type. In some cases, the average life cycle of an instance can be substantially longer than that of its type, for example, cars that are still on the road but are no longer built according to such specifications. Equivalently to the relation of DT instance and DT type, the DT portfolio monitors and optimizes the life cycle of the product types with data from different sources. The DT of the portfolio provides design, systems, supply chain, product, and value proposition engineers with the possibility to examine the life cycle data  
Figure 8: The digital twin as the thread connecting product management levels across time. of instances and types generated by the DTs, discover patterns, and gain insights to optimize and innovate the types. These patterns may also unveil changing customer demands that may be matched with novel product and service concepts [87] to be implemented in future types and instances. Congruent to their real-world counterparts, their digitized versions on all product management levels also comprise a life cycle where they are developed and produced, used and maintained, and in some cases also recycled [88]. The separation of portfolio, type, and instance is a fundamental concept in the presented framework and an exceedingly relevant difference to traditional models. **Different generations--**The DT concept represents a holistic model-based product description for current and future life cycle stages [58]. It includes a wealth of helpful information on the current and subsequent life cycle phases [89; 90].