Smoothing the design lifecycle with digital twins

GARTNER PREDICTS that by 2022, or perhaps sooner, more than two-thirds of companies that have implemented IoT projects will have launched at least one digital twin in production. For machine builders, the nearly unlimited uses of a digital twin can provide a competitive edge. There are three key advantages that the technology can unleash in your business: a better way to design and sell machines; faster, more consistent commissioning; and optimised operations for the customer.

In its simplest form, a digital twin is a digital representation of a physical asset or system. However, it is more than just a visual representation, it is a dynamic model that is based on the physics of the machine or system and behaves and responds to conditions exactly as it would in a real operational scenario. From iterating designs before you cut steel, to testing the controls for a machine before it is bolted to the floor, to creating experienced workers before they touch live controls, the opportunities to apply a digital twin are nearly unlimited.

The marriage of the 3D CAD design of the system with the control logic before even one part has been ordered is the real magic of these systems, such as Rockwell Automation’s Emulate3D. It creates a dynamic digital twin that not only allows the system to be operated and tested using realistic loads and products in the system, but also allows operators to be trained virtually in real-life operational situations while mitigating risk.

Physical vs. logical truth

One of the challenges that manufacturers face is that all too often industrial automation systems comprise two descriptions of the truth, a physical one and a logical one. The physical truth is the CAD model of the system or machine, and the logical truth is the control system. The quandary for operators is that these two versions of the truth are often askew.

It is often not until the commissioning phase of the project that this misalignment becomes apparent as this is the first time that the two truths are brought together. At this stage, the outcome is often a system that operates below expectations in some way, or that requires costly modification to meet the specification. This discrepancy between the two truths does not have to be significant for the system to perform below expectations, but the costs associated with changes and delays at the commissioning stage can have a calamitous effect on the effectiveness of the system and put into question further automation decisions.

With a digital twin employed, these two truths can be integrated early in the design process so the combined operation of the mechanical and the logical systems can be observed, tested, debugged, and verified safely and accurately. There is also the benefit of allowing better cooperation between the two teams responsible for each truth as changes are easier to implement. By creating a dynamic digital twin comprising both the CAD and the real operational logic of the system, it creates a powerful tool for putting a system through its paces in a virtual environment, where the cost of changes is minimal compared to those incurred at the commissioning phase.

3D simulation and emulation software, such as Emulate3D, provides an ideal platform for creating dynamic digital twins. It allows the CAD to be imported from a wide range of standard formats, create kinematic behaviours to reflect the movements of the real system, and connect the model control items to the real control system via a tag browser. After this all that is required is to create loads to drive the system and the digital twin is live and ready to be operated via the HMIs that will be part of the final system. The two potentially conflicting truths are now accurately represented in a virtual environment. Their full operation can be exhaustively and repeatably verified and demonstrated before committing any resources to their manufacture.

Ease commissioning woes

When it comes to commissioning a project, the digital twin can be an asset that ensures the project scope can be fulfilled on budget and in a timely fashion. As the date approaches for commissioning a project, the stakes increase when it comes to performance. There is a myriad of potential complications, from a functionality problem such as an unexpected stoppage or a missing sensor, or a concern around the HMI’s sequence or layout. Whatever the obstacle, it is certain to be expensive. It is not unknown that correcting an issue during commissioning can be up to 100 times more expensive than rectifying it during the design phase. Cost is not the only criteria that success is based upon, and rework that delays the customer’s production start date can also have further ramifications.

To alleviate these risks machine designers are looking to virtual commissioning utilising a digital twin and simulation to perform controls testing before the machine is built. The benefits of the strategy are apparent, by identifying and potential design issues early in the design and build cycle enables them to be rectified in a timely manner, saving costs, and keeping the project on schedule.

The dynamic digital twin that is used for this purpose is more than a 3D visual model. Physics are added to the design and this runs a simulation that shows how it operates and interacts with people or other machines. This review can be conducted as soon as the machine or system design is complete, long before any purchasing or manufacturing is undertaken.

One machine builder that has benefitted from virtual commissioning is Daifuku Webb, a maker of material handling systems. The company uses virtual commissioning to test PLC code in-house before it goes to the field. In one project for an airport customer, it used virtual controls testing to reduce the amount of time its engineers spent in the field from several months to about three weeks. System installations also go smoother because the PLC code functions have already been tested, while Daifuku can thoroughly demonstrate the functions of its systems before bringing them to the field.

Creating a digital twin is a straightforward process that can be achieved in three steps. Staring with the CAD files to which are added a mock-up of the machine’s movements and devices such as sensors. Finally, the CAD in married with the controller and its tags. With that achieved testing out the machine and its logic can be undertaken digitally.

A system that has been put through the rigors of virtual testing and commissioning benefits everyone. Production workers gain a more thoroughly tested system that performs to spec. System integrators can predict commissioning times more accurately and plan accordingly. And all stakeholders win when projects come in on time and on budget. The use of virtual commissioning adds value to the whole process not only by producing tangible returns, but also by raising the level of confidence associated with the process of implementing industrial automation systems.

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