The Virtual Commissioning Workflow - Maplesoft Engineering Solutions

The Virtual Commissioning Workflow

With the right tools in place, it is now possible for many organizations to adopt VC techniques for their machine design projects. They may use VC in order to reduce their overall commissioning time, to reduce commissioning costs, or to create a more reliable time to market for reputation purposes. While the applications and specifics can vary greatly, a typical virtual commissioning (VC) process has many commonalities.

Construct the Model-Based Digital Twin

To begin, a model-based digital twin is constructed using a system-level modeling tool. Using these tools, the virtual model is developed either from existing CAD information, or from design concepts that are realized using the tool’s component libraries. In this workflow, the system-level modeling tool, MapleSim, is used to demonstrate the process of starting from CAD models. Developed by Maplesoft, this tool allows for automatic CAD import so the digital twin can start with validated geometries of the design concept. Without previous CAD models, engineers can begin by using drag-and-drop components that can be customized to their specific designs, but this process typically requires more time and effort than CAD import.

The CAD information is brought into MapleSim, where it is categorized into rigid bodies and frames with corresponding center of masses, among other parameters. These bodies generate individual component blocks that can be used in conjunction with all other standard and custom components required during model creation. The amount of fidelity required for a digital twin is fully dependent on the requirements for simulation. A higher fidelity model requires more effort to create, but can answer increasingly specific design questions, and offer a more realistic representation of performance for PLC validation. In the past, higher fidelity models were either too difficult to create, or simply couldn’t be used when hardware validation required real-time simulation performance. Software tools like MapleSim are designed specifically to produce simulation code that is optimized for simulation speed, allowing high fidelity digital twins that can be useful for a variety of VC requirements.

Actuate and Analyze the Digital Twin

Before connecting the digital twin to automation software, the simulation software tool is used further to investigate the model and, optionally, perform a variety of design analyses for functional verification of the plant model itself.

The validated mechanism, now in MapleSim, can be actuated in a variety of ways, depending on what data is available to the engineer. Using standard MapleSim components, such as servo motors, the actuation can be defined for each joint, specific to the particular motors and requirements of the design concept. Users also have the option to define actuation by importing external libraries of actuators, or by using empirical data from specific motors. Model inputs are defined by parameterizing the system for the specific requirements of the VC process, which is a common task accomplished with parameter tables available using the simulation tool. Motion paths and loading are defined in conjunction with design requirements, using the inverse kinematic equations that are available through MapleSim’s analysis features. These details form an important part of defining the inputs to the model, which are maintained when the model is exported as a Functional Mock-up Unit (FMU).

Lastly, the model outputs are defined as a collection of sensors and probes according to design requirements. Using a system-level modeling tool like MapleSim allows the engineer to specify outputs for any variable of system performance, which is carried into the FMU for access by the automation software.

Integration with Automation Software

When the digital twin is created, it can be exported by MapleSim as an FMU, which includes all of the necessary information for usage by the automation tool. The FMU includes optimized C code that specifies the set of differential, algebraic, and discrete equations that describe the behavior of the physical system. The FMU standard is supported by an increasing amount of automation tools, such as B&R Automation Studio. Using an automation tool, the engineer will import the FMU, and will then have access to the model’s inputs and outputs, in order to define their connection with the virtual PLC code.

At this point, both the virtual model and the virtual PLC code reside within the same environment. While testing can begin, it is also possible to use PLC code that is designed with the digital twin model in the controller logic itself. If the digital twin is of a sufficient level of fidelity, and validated for accuracy, the engineer might forego the requirement for specific physical sensors on the final product, and instead instruct their PLC code to call for specific information from the digital twin instead. This technique is an emerging method to reduce the costs associated with installing expensive physical sensors on a machine, since the digital twin is able to simulate the system in real-time, offering the same information that a physical sensor might.

Next: Virtual Commissioning Techniques

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