Two Design Approaches – Will MBSE Design Prevail?

Exploring the benefits of MBSE design

Products are increasing in complexity at an astonishing rate. Smartphones are just one example: today’s devices combine the functionality of yesterday’s phones, cameras, calculators, and pagers and place desktop applications and internet browsers in the palms of our hands. Advancing electrification, mass miniaturization, and IoT-driven digitization are making a vast range of devices smarter and smaller.

To cope with these changes, manufacturers must transform the way they develop complex systems. This post compares and contrasts the traditional and modern approaches to developing and verifying products.

The traditional approach: design, build, test

The traditional design approach follows a process that looks like this:

1. System architects and engineers take high-level product requirements and distribute them across teams.
2. Each team starts its design work, documenting requirements and sub-requirements and their development plans.
3. If the work of one team is likely to have an impact on that of another, there may be some loose communication between them. In general, though, teams work separately. They perform quick, abstract calculations and capture them on custom spreadsheets.

With this disjointed approach, everyone keeps their head down and gets on with the job. When every team is ready, they move to the prototyping and testing phases.

On paper, this may look like a feasible way of working, and when the end product is simple, it may be. But in practice, inconsistent design processes create problems, especially with complex products. For example, one team may come up with an innovative way to work within the constraints on its requirements. Another team may tweak its requirements to produce an elegant solution. Other teams may push back on their requirements and request significant changes because they believe the requirements are infeasible.

Trouble awaits

Thanks to the diversity of these approaches, the teams’ designs diverge. This creates problems that will manifest later in the product development lifecycle when different teams’ designs must come together. Indeed, without an established and robust way to conduct spreadsheet calculations, every team’s results could be dramatically off the mark. When that happens, poor-performing designs can move straight into the testing phase. Simply put, because there is no communication across teams, their approaches are opaque and inconsistent, and problems creep in.

In the prototyping and testing stages, these problems become evident. The proposed design is amalgamated by the testing and design teams to create a prototype, which has issues—perhaps thousands of them. When tested against original requirements, the prototype fails. The design teams go back to the drawing board, change the design, and create another prototype at considerable expense. Only for it to fail again during testing. Then, another prototype is created, and another, with each iteration needing more work and failing testing. The project incurs significant delays, and costs mount.

The modern approach: model, analyze, build

The modern approach is quite different from the traditional approach. Collaboration, visibility, and consistency are at its core. Systems engineers, architects, and design team leads work together to create a digital model of the entire system. The model incorporates all system requirements, functions, logical architectures, and physical architectures while allowing individual teams to work within their areas of expertise.

This approach, model-based systems engineering (MBSE), is highly dynamic. Changes to the model can be made on an hourly basis and shared with the impacted design team. The system’s central single source of truth governs such changes, ensuring coordinated activities between the engineering and design departments. As teams move into the detailed design stage, they have the freedom to implement their designs within the defined design envelope. But, if the implementation violates the envelope, the integrity of the model must be considered. Systems engineering will consider a resolution to the violation in the context of the entire system model. Something as simple as a new weight allocation of several kilograms could resolve the violation. This approach ensures the preservation of model integrity.

This modern MBSE design approach is also highly iterative, enabling teams to run a variety of simulations and analyses to test their design and the impact of any variances outside the assigned design envelope. Therefore, teams will have insight into the feasibility of their design in the context of the project’s requirements. Design teams apply MBSE design to every sub-system design, giving the teams confidence in their individual work while guaranteeing that the overall system performs as expected and fulfills its requirements.

Beyond the gate

As the system model moves through design, prototyping, and testing stages, it must pass numerous verification gates to ensure model consistency. Because simulation and analysis allow teams to test and verify their designs in the virtual world, when they move to the physical domain, there are no nasty surprises. Simulation and analysis help uncover and resolve issues. The common digital thread running through the MBSE design process provides much-needed communication and visibility to design and engineering teams. As the design reaches physical testing and prototyping, confidence is high that each sub-system and in-turn the entire system will perform as intended. In other words, the consistency and collaboration of this modern approach give organizations a way to expedite their product development processes.

Summary

• Today’s smart products are increasingly complex. Changes to the development process are a must in order to manage this complexity and keep projects running on time and within budget.
• The traditional approach is heavily siloed—different teams work on different requirements. There is no cross-team consistency or visibility, and each team may take a different approach in tackling its requirements. Multiple prototypes are required because problems become apparent only during the physical testing stages when everything comes together for the first time—a time-consuming and costly approach.
• The modern MBSE design approach uses simulation and modeling to analyze and build a product in the virtual world. This highly iterative way of working allows design teams to identify issues and deal with them early in the development lifecycle. Furthermore, teams are not siloed—they all work with the same digital thread, which fosters cross-team consistency. As a result, the product prototype passes the majority of its tests on the first pass, expediting the development process and reducing costs.

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