Cross-discipline 3D model-based tool chain facilitates agile cable harness development

This development includes EE, 3D and configuration data models, and it requires detailed electrical as well as thermodynamic simulations. Mutually dependent subsectors such as wiring, geometry, EE elements and software have to interact with one another. However, the common, document-based procedure can no longer meet this demand, because it is designed for isolated processes. When data is transferred manually, errors creep in easily, and the impact of specific changes on production costs or functional safety can be costly due to the many interdependencies. A remedy for this issue is smartCable GmbH's model-based tool chain. With the aid of a digital twin that grows along with your needs and that can be accessed by all of the subsectors, the tool chain offers an interdisciplinary approach that encompasses and links all of the developmental steps. The entire process remains transparent and generative, from the first draft of the cable harness architecture to the final manufacturing information.

In 2021 almost 356,000 new EVs were registered in Germany, setting a new record. And the first automated drive systems are cruising on European roads as well. For example, the Drive Pilot in the new Mercedes S-class controls the car up to 60km/h, which meets the requirements of level 3 of autonomous driving. But alternative drives and AI-based control also pose new challenges to the automotive industry, explains Uwe Prüfer, Head of Research and Development at smartCable: "Cable harness development is undergoing changes. Few or no automated process steps and the classical silo mentality common to the various disciplines are no longer able to meet the need for the further development of high-voltage harnesses, for performance of thermal and electrical or electromagnetic simulations, and for essential redundancies and modified standards such as ISO 26262."

When coordinating many systems applying manual data transmission, it is easy to make a mistake, which of course increases the development costs and time. And if changes are made at the geometry level as well, their impact on other components, such as wiring or EMC management, are not readily apparent, and the ultimate production costs can only be conjecture. It is essential to efficient and targeted development that changes are quickly calculated and communicated between the individual disciplines, that simulations and validations are seamlessly incorporated into the process, and that comprehensive application and product life cycle management systems (ALM/PLM) are integrated. Prüfer confirms: "Cable harness development has to distance itself from the document-based approach, which requires quite a few manual steps as well as complicated data exchange between different systems and formats. Only a model-based approach can properly link the subsectors and facilitate a transparent development process."

Generative development with a digital twin

Accordingly, smartCable's tool chain works on the basis of a cross-discipline data model that is a digital twin of the actual cable harness. The model grows dynamically as development advances. Via interfaces designed for their respective subsectors, so-called views, all participants such as designers or manufacturing planners access the central model. This can be architectural drawings, EE drafts, 3D topologies, simulations or configuration files. Prüfer explains: Every point of the 3D topology refers via the data model to the respective counterpart in the cable harness drawing (which is not to scale) and the scaled formboard drawing. This way we ensure that all of the access points have access to the same constructive content."

Since modifications in a certain subsector do not have to be manually transferred to another subsector but instead can be generatively factored into the central 3D data model, the error rate falls and the changes are traceable at any time. If the 3D model is modified, the effects on the electromagnetic and thermal compatibility or on the ultimate manufacturing costs can be determined automatically. Individual rule catalogues that can be expanded as needed are integrated and serve as the basis for the algorithm to check the conformity of the various development steps with standards and quality requirements, e.g. those specified by the OEM or by law. Simulations that are essential to e-mobility and autonomous driving can also be directly derived from the central data model, without having to be prepared manually. Not only does this save valuable development time and reduce the time-to-market, it also facilitates thorough cost control.

Scalable software with integrated engineering knowledge base

"Technological advances require agility, which means that the respective software components have to adapt flexibly to new circumstances," explains Prüfer. "To enable such a high degree of scalability, our generative tool chain uses a CAD platform and a data model with no size restrictions." smartCable has been working closely with the CAD designer Dassault Systèmes to achieve this. This means that the solutions are directly integrated into the CATIA development environment commonly used in the sector, instead of cumbersome import via external interfaces. Another helpful tool is the specially designed Engineering Knowledge Base, which serves as the foundation for automating validation and testing in the design process. The patented process provides engineering know-how, such that algorithms can make decisions on the basis of the know-how. "This is how smartCable emulates the procedure applied by an experienced designer, eliminating many manual steps and significantly shortening the overall development time," summarises Prüfer.