How To Solve Automotive Electrical Design Challenges To Get To Market Faster

Getting the wiring harness right is a vital part of reducing vehicle weight and cost.

popularity

By Dan Scott and Ulrike Hoff

The never-ending development of new technologies in the automotive industry has led to the Content Dilemma, the conflict between the technology content that vehicle manufacturers try to integrate into their vehicles, and the weight, cost and packaging space required for wiring harnesses. Current technology trends driving the Content Dilemma include electrification, autonomous driving, artificial intelligence (AI) and the connected vehicle. Another factor is electric vehicle driving range – the more miles, the better.

Vehicle mass plays a key role in determining a vehicle’s range, thus, minimizing electric vehicle weight is crucial to bringing a competitive and successful vehicle to market. These new vehicle technologies require additional electrical wiring and other electronic components, increasing its weight. The electric powertrain alone adds about 30% more weight compared to an internal combustion engine powertrain.

Autonomous driving also requires a multitude of hardware redundancies and fail safe mechanisms to prevent single points of failure that could disable the autonomous system unexpectedly. System redundancies are critical because unexpected failures may cause the vehicle to crash if the driver isn’t paying attention or actively involved in the driving and steering process. But these safety redundancies add significant weight and cost to the wiring harness.

Trends create new challenges for harness development
AI in vehicles enables facial recognition, computer vision, and other machine learning algorithms to help personalize the user experience and vehicle settings by processing and ‘learning’ from incoming data. This requires a myriad of cameras and other hardware connected to an electric control unit via coax or high speed data cables, which are significantly larger, heavier and more expensive than conventional automotive wiring. Vehicles are also becoming highly connected as part of the internet of things, transforming the vehicle into a seamless hub for entertainment, communications, and productivity.

As these technologies are connected together, the wire harnesses add weight, bundle diameter and cost (Figure 1). Some modern vehicles contain about 40 different harnesses, comprised of roughly 700 connectors and over 3000 wires. If taken apart and put into a continuous line, these wires would exceed a length of 2.5mi (4km) and weigh approximately 132lbs (60kg). There can be more than 70 specialty cables, such as coax, high speed data, and USB cables, compared to 10 in older cars.


Figure 1: Modern automotive wiring harnesses continue to grow in size and complexity as new features are integrated.

How can today’s automotive manufacturers solve the Content Dilemma to reduce the impact of added content and technology on the weight, cost and packaging space required for wiring harnesses? Possible solutions to reduce harness weight, such as ultra-small diameter or aluminum wiring, are being implemented in a limited number of use cases, but a large scale application throughout the entire vehicle is currently not sufficiently supported by the market.

A better approach is using advanced software solutions that support tradeoff studies to optimize module locations and identify any modules that can be combined to save weight, cost, and reduce bundle sizes (Figure 2). The ability to compare and analyze layouts for their impact on harness weight, cost, and bundle diameter enables engineers to choose the optimal system architecture.


Figure 2: Advanced software, such as the Capital Suite from Mentor, enables tradeoff studies with cost, weight, and bundle size metrics to optimize the design of electrical systems.

Reduced time-to-market: the timing dilemma
New vehicle development cycles at an established OEM require four to five years. In comparison, most startup electric vehicle (EV) companies aim to launch a vehicle in a much shorter period of time, often developed from scratch without the legacy of previous vehicle programs. This short time to market leads to short iterations or development phases which become problematic when paired with the long lead times required for harness development. Typical lead-time for harnesses, from design release to product delivery, is approximately 23 – 26 weeks. Variance in lead-time depends on the number of changes and project progress in the development cycle. To meet deadlines for the next development phase, harnesses have to be frozen (where the data/design is released and must go through formal change management processes to be updated) with little to no time to examine or implement lessons learned in between development phases. Frequently, vehicle testing hasn’t even started when the next freeze comes due. This can lead to massive rework efforts once the next build phase starts, or “rush” change requests into the harness design before the next freeze date. Both alternatives can deteriorate the quality of the harnesses, causing unnecessary delays during functional validation.

Reducing lead times during the engineering and manufacturing phases benefits all the engineering teams. More lead time helps teams identify issues, determine appropriate wiring changes, and implement those changes in the design for the next validation phase. How can lead-time reduction be achieved? By eliminating manual steps in the development process and automatically cascading information from one step to another (Figure 3). This significantly reduces mistakes and the need to double check work results. The goal is to create a seamless integration between the vehicle manufacturer’s and supplier’s tool chains.

Automated data transfer is critical for harness design
As more automotive startups enter the market, harness development tools with an integrated device transmittal database and component library will provide a profound advantage to wiring teams. This eliminates the need for tedious data gathering via Excel sheets and the manual data transfer into logical schematics, a process prone to human error. Harness development tools will streamline and automate the process to reduce mistakes and improve the overall harness quality from early design stages.

This central database can run automated reports for open-ended circuits, missing load information, and more. The integrated device transmittal database can be enhanced with certain change control mechanisms. With these enhancements, this database will provide the necessary structure and automatic change management immediately. The component library will considerably reduce the need for part research to find terminals, seals or mating connector part numbers. Mis-pinned connectors, caused by operator error or incorrect information on the endview definition, are among the most common errors. A component library that provides endviews for each part number will eliminate the guesswork when assigning pin numbers to cavities and prevent these mistakes.


Fig. 3: Automated data transfer reduces errors in the harness design by streamlining the interaction between domains.

The release engineer of a device can draft the device transmittal directly in the database and submit it for approval. The change will be updated automatically in the logical schematics, eliminating the error-prone process of manually updating schematics from Excel files. It also prevents release engineers from making changes to outdated local copies, overwriting changes made to the device transmittal since the last update. Lastly, for each released set of logical schematics, an automatically-generated list of change requests is implemented in each release, linking each change back to a specific harness revision for future reference.

Conclusion
Modern harness design and engineering tools provide an elegant solution to the problems being wrought by automotive innovation. Using tools such as Capital, with high levels of automation, advanced metrics and analytical capabilities, engineers can perform tradeoff studies to optimize materials, component placement, and routing for minimal harness weight, cost, and bundle diameter. Modern design tools can automate data transition between engineering teams and even between manufacturers and suppliers. Finally, innovative harness design software suites feature integrated change management tools that ensure all teams are working with up-to-date data. By adopting these solutions, established automotive OEMs and startups can better tackle the challenges of the new automotive landscape.

For more information download our new whitepaper, Automotive Trends Create New Challenges for Wiring Harness Development.

Ulrike Hoff has worked at multiple OEMs and start-up companies in the automotive industry for the past 15 years, including Daimler, BMW, FCA, Fisker Automotive and Faraday Future. During this time she specialized in the development of wire harnesses and was able to obtain an in-depth insight into the wide range of wire harness development processes at OEMs and start-ups. Currently she is consulting at an LA-based automotive start-up, supporting their validation prototype build with her expertise.



Leave a Reply


(Note: This name will be displayed publicly)