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Edited by Rick DeMeis
Part 1 of this series covered in-vehicle networking simulation and analysis.
Part 2 covers simulation-based early validation of vehicle electrical systems and power management.
The rapid increase in vehicle electrical features has significantly impacted the engineering of wiring harness systems. The proliferation of options and various vehicle platforms requires the use of tools that enable data consistency and option handling, as well as complete and efficient wiring verification within the vehicle. This article will detail a proven methodology that contains the necessary steps to ensure the creation of robust wiring harnesses.
The development of todays wiring harness systems has become a challenge for design engineers. The complexity of wiring harnesses, the proliferation of options, as well as the sheer volume of data, all require a development environment that enables consistent and reliable in-vehicle network data management. In order to address the quality of in-vehicle network development during the concept phase, early verification of the network concept must be implemented.
There are three requirements that are instrumental for fostering robust wiring development from concept to production:
Consistent in-vehicle network data management
Verification of in-vehicle network implementation
Automated output of manufacturing data
With the Saber development environment, Synopsys provides a solution to address these challenges. The Saber Harness module is a schematics-based system designed specifically for the development of wiring harness systems in the automotive industry.
Global engineering and the Single Design Database
Wiring harness systems are usually engineered by a large team distributed across different locations. Assurances must be made that all designers are relying on the same data at all times. These data include information such as connector types and their pin assignment, wire types and lengths, wiring harnesses bundled to wiring harness families, etc. If multiple databases are used in parallel, there might be problems, such as duplicate pin assignment due to inconsistent management of wiring harness data.
Saber Harness uses a technology known as Single Design Database. Within this technology all wiring harness data is stored in a central repository. This repository can be accessed in parallel by many designers, while all designers also always receive a copy of the master design from the repository. Only a single user can make design changes to the unit that is currently checked out. During this time, all other users have access in read-only mode.
To avoid blocking the design process, Saber Harness uses a modular approach for the construction of in-vehicle network designs. The wiring sets drawn in the schematic editor can be distributed across multiple design sheets, making wiring design more concise. It also enables access definition for different design sheets, allowing simultaneous access to the design by multiple users. Defining write permissions for dedicated sheets, allows different users to simultaneously make changes.
The figure below shows the general flow during access to the central repository. There are different methods used for in-vehicle network implementation. For this reason, a methodology is required to manage the options efficiently, without creating extraneous effort. Drawing a schematic for each of the options would be a rudimentary and time-consuming solution that would produce an unnecessarily high volume of data. Saber Harness uses the Single Design Database concept here as well.
Schematic Editor
In this case, the wiring harness, including all of its components, is being set up once in its maximal stage of expansion within the schematic editor. Afterwards, the designer defines the assignment of feature options and wiring harnesses respectively for each component. The desired option can then be selected graphically. All components that belong to another option type are masked out; thus, the designer is able to access all options without the need to generate multiple schematics.
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Option handling through filtering
The figure above shows the concept of option handling in Saber Harness. The complete system is visible in this case for three feature options. For the three possible alternatives, all components not associated with the respective option are automatically masked out; however, the flexibility extends well beyond pure option handling. A general filtering option allows the user to prepare the in-vehicle network representation according to user-defined criteria such as wiring harness families.
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