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Auto Design Demands Integrated Electromechanical Solution

Release Date:2018-08-06

Major disruptions in the automotive market are igniting innovations in autonomy, mobility as a service, light-weighting, AI, and connectivity. These innovations are causing vehicles to be far more complex and sophisticated than ever before. Most of this complexity is due to the growth of electromechanical systems that support intricate software-driven solutions. Legacy engineering systems and processes are not adequate to support multi-discipline dependencies across electrical, mechanical, and software designs, and they do not handle the constant changes and updates required to deliver the final product.

As automakers turn their focus to these electronics-laden, complex systems, it is becoming clear that a new solution is required for electromechanical and software system design that is highly optimized for vehicle performance attributes. Electrical CAD (ECAD) design teams that develop automotive electrical systems and wire harnesses need to seamlessly work with their Mechanical CAD (MCAD) and software engineering partners that develop the mechanical and software systems (Fig. 1). It is critical that engineers across systems collaborate from the start of the development process in order to identify conflicts early and then constantly collaborate to ensure alignment between each system prior to design completion and to avoid costly design changes later in the process. This pivot to complex systems means that automakers are examining “old school” practices in order to improve them to save time and money, eliminate issues, and to move toward first-pass success for electromechanical design.

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Fig. 1: ECAD, MCAD, and software engineers need to seamlessly collaborate.

Understanding ‘old school’ practices
Traditionally, electrical, mechanical, and software teams work in “silos,” they typically use completely different toolsets, and they could even reside in different locations. Some companies further split the ECAD designers into schematic capture and wire harness teams.

Mechanical and electrical CAD systems have different ways of presenting the structure of the same object. In an MCAD system, a computer module might be represented as a box enclosure, circuit board, mounting features, and connectors. However, an ECAD representation of that same module could be a model or a symbol in a schematic. Certain electrical functions might be mapped to several different circuit boards and connectors, making it impractical to associate a single function to a single physical part.

Electromechanical development cannot effectively be performed without communication between the MCAD, ECAD, software, and PLM system (if one is deployed). For example:

  • Space must be reserved, an MCAD task, for electrical components and wire harnesses in the car defined by ECAD.

  • Voltage drop calculations, an ECAD task, cannot be done without wire harness bundle lengths, an MCAD task.

  • Consolidated product BOMs cannot be created, a PLM task, without complete wire harness BOMs, an ECAD task.

  • Certain electrical requirements, such as the distance between power and ground pins, cannot be verified by only using ECAD and MCAD systems.

  • Electronic computing units (ECUs), sensors, and actuators cannot be defined without identifying the interactions by the driving software functions, a software architecture task.

Communication between teams is often a manual process (Fig. 2). For example, designers pass hand-crafted drawings, spreadsheets, notes, email, or annotated documents between each team. Teams rely on design reuse, marking the designs manually for new or modified elements. This means that data could be misinterpreted, teams could utilize out-of-date data, or designers might need to re-enter data into their own specialized tools. Even worse, data could be missing without designers being aware of it, leading to errors or costly updates deep into the design cycle.

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Fig. 2: MCAD and ECAD engineers are often isolated.

Some automotive companies have developed their own software and processes for collaboration. But they have found that maintaining these tools, making sure that they are accurate, and training new employees to use them is extremely expensive.

Other companies create XML formats in order to pass data between the ECAD and MCAD tools and their PLM system. While passing around XML files is an improvement over manual techniques, this methodology still suffers from problems:

  • Because designers must manually export or import the XML, after one domain completes design changes, they must wait for the designers in the other domain to review and accept or reject the proposed changes. This increases downtime on a project, prolonging the development process.

  • When proposing design changes, the ECAD and MCAD designers are doing so with only the knowledge of what the changes mean for their domain. Therefore, a designer working in the ECAD environment could propose changes that would cause spatial or physical violations and not know this until the MCAD engineer reviews and rejects the changes.

  • While XML is a standard for specifying any data schema, the specific data is not standard. So other tools in the design flow might not understand the XML content.

Another disadvantage to “old school” approaches is that supporting many variants from the base electromechanical specification is tedious, time-consuming, and fraught with error. For example, the wire harness configuration for a luxury package that includes a feature like assisted parking might be very different from the harness configuration for a base model of a car without this feature.

Thus, the biggest issues that plague a non-integrated electromechanical solution are:

  • Design changes and updates are not automatically managed across adjacent and highly dependent disciplines.

  • Vehicle integration becomes a highly iterative process that can be affected by costly changes late in the process.

  • Supporting and optimizing multiple electromechanical configurations is almost impossible.

  • Assessing design completeness and compatibility is extremely challenging.

  • Adding additional engineering resources to resolve issues causes inefficiencies and adds significant cost.

What is actually needed is a “new school” integrated electromechanical solution.

Moving toward the “new school” solution
It is clear that automakers cannot perform electromechanical design by continuing to isolate ECAD, MCAD, and software teams and employing “old school” techniques. Electrical interconnect implements functional integration within a mechanical host while satisfying software needs. Constant multi-discipline design change and configuration complexity require integrated solutions incorporating advanced data management and workflow orchestration capabilities. The electrical, mechanical, and software design processes should be more connected, integrated, and collaborative than they are today.

Connecting the domains
As automotive OEMs develop new vehicle platforms and business models to market innovative electromechanical product features to customers, they need to make sure that, behind the scenes, all engineering domains are tightly connected. This allows decisions, tradeoffs, and engineering optimizations to seamlessly flow across domain boundaries (Fig. 3).

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Fig. 3: Tightly connected engineering domains.

A key technical aspect in this new solution is to reduce or eliminate manual data exchanges. The complexities across electrical and mechanical domains demand integrating MCAD and ECAD tools through the use of APIs in addition to manual or file-based exchanges. This means that the two domains can be directly connected so that any changes or new information is immediately available to the designers across domains while they develop their respective designs in their own toolsets.

With this integration, teams can design electrical system and wiring harnesses with explicit knowledge of the unique environmental conditions of the mechanical design. This allows the ECAD designer to account for the impact of these conditions on the electrical performance when designing the electrical system. On the mechanical side, designers can make space reservations and adjust for the severity of bends in the harness to account for the wiring bundles that must route through the mechanical structures. With access to this contextual information, both electrical and mechanical engineers are able to quickly reconcile incompatibilities between the ECAD and MCAD designs.

A new electromechanical solution should also integrate with the PLM workflow tool, the associated upstream design tools, and the downstream tools for manufacturing the entire vehicle (Fig. 4). In that way, a digital thread unites the entire process from requirements to design to manufacturing the car on the factory floor.

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Fig. 4: An integrated design flow.

Managing change and multiple variants
Because of the design complexity of today’s vehicle electromechanical systems, there can be many changes and iterations between the ECAD and MCAD domains (Fig. 5). For example, changing the location of a sensor in the car could spawn multiple changes for both electrical and mechanical designs. Therefore, a robust change management methodology must be in place.

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Fig. 5: Typical change triggers that require synchronized change management.

The challenge of change management is how to track changes between both domains quickly and efficiently. There are two major aspects of an effective change management solution:

  • Automatic merging of data and a clear report of the changes to the designer. Using this report, the electrical engineer can choose to accept or reject each change individually rather than a whole set of changes. The designer should be able to cross-probe between the electrical and mechanical designs and highlight changes in either the ECAD or MCAD environments to understand the proposed changes.

  • A change policy that defines the master of the data and the direction in which changes flow. For example, a policy rule can be set that MCAD designers are only able to update the weight attribute of a connector but not the electrical characteristics.

Electromechanical variants increase the complexity of change management. Any given vehicle model can be equipped with a variable set of electronic systems and features, meaning that many versions of a wiring harness might exist. Variants require an intelligent, unified change management system that connects to a PLM system. This complete system provides mechanical and electrical engineers with up-to-date variant information relevant to their domain without forcing either discipline to adapt to the other’s database.

Putting it all together
With this new system in place, the flow of information between ECAD and MCAD teams defining electromechanical systems allows for first-pass success. Let’s take a look at an example of how this could work. In electric-drive cars, there is a requirement that wires carrying high-voltage power signals need to be separated from data wires to prevent electromagnetic interference from distorting the data signals. The integrated electromechanical system can meet this requirement by following these steps:

  1. The ECAD designer retrieves the requirement for signal separation for the wire harness from the PLM system.

  2. The ECAD designer implements the requirement in the associated electrical design.

  3. The MCAD designer defines the bundle routes (3D harness topology).

  4. Both designers associate the 3D harness topology with the electrical design.

  5. The ECAD designer runs the rule that checks for signal separation and performs simulation and design rule checks to verify the design.

  6. The MCAD designer back-annotates wiring data and verifies the complete mechanical design.

  7. The ECAD designer releases the electrical design/BOM and verification report to the PLM system.

The drive away
As the electronic systems content of internal combustion, electric, and autonomous vehicles grows exponentially, the “old school” techniques of designing electromechanical systems are not adequate to meet production schedules. It is time to invest in new, integrated tools and processes that enable the ECAD, MCAD, and software domains to intelligently collaborate to ensure first-pass success. Using this “new school” approach, we have seen companies already achieve significant benefits in electromechanical engineering, including:

  • Reduced costs and cycle times for harness manufacturing

  • Improved engineering staff satisfaction

  • Intellectual property retention and protection

  • Engineering innovation

To read more about this integrated electromechanical solution, see this whitepaper.

— This article was co-authored by Kevin Paul, Engineering Director, Capital Products at Mentor, A Siemens Business, and Piyush Karkare, Director of Global Automotive Industry Solutions at Siemens PLM Software. Paul is leading the development of various Capital electrical and wire harness design products at Mentor. Piyush has over 25 years of industry experience, having spent over 16 years at Ford Motor Company, where he was involved in electrical engineering systems, electrical distribution systems, in-vehicle software engineering, and management solutions.

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