Model-based design: latest solution of engineering problems

Computer-aided engineering (CAE) capabilities continue to evolve and expand as the increasing power of desktop computers and graphic displays allows software vendors to develop more power software. At the same time, the decreasing cost of these computers enables users to benefit from the productivity these CAE packages offer.

Design engineers use a variety of CAE tools, including large, general-purpose commercial programs and specialized programs. A CAE tool is typically made up of a number of mathematical models encoded by algorithms written in a programming language. These tools are being used to analyze the robustness and performance of components and assemblies. It encompasses simulation, validation and optimization or products and manufacturing tools. Solution of a single engineering problem frequently requires the application of several CAE tools. One of the newest and popular branches of CAE is model-based design. Model-based design allows engineers to develop system-level simulation models that mathematically describe the dynamic behavior of devices and equipment. The models incorporate multiple domains of engineering, including, but not limited to, mechanical, electrical and control systems. Well suited to mechatronic development, model-based design emphasizes on embedded control development.

Model-based design saves time and costs

Equipment makers who are wrestling with the complexities of developing embedded control solutions seek the use of model-based design. Model-based design reduces the time and costs associated with traditional approaches that usually involve prototype design on the actual system hardware. Performing model-based design allows equipment maker to detect errors early in the simulation stage of the project, instead of during the hardware phase where problems are more difficult to trace and costly to fix. In model-based design, the final stages involving hardware prototype tests are done to validate good designs, not to catch bad designs.

Model highlights mathematic specification

Most engineers who witnessed the evolution of CAD should be familiar with the concept of model-based design. In model-based design, the simulation model is a mathematical specification of the system, much as a 3D CAD file is a geometric specification. The idea of a model as a specification is an important concept. Models in both model-based design and CAD represent unambiguous definition of the product, dynamically and geometrically, respectively. This table explains the parallels of these CAE solutions.

Special capabilities offer added benefits

Model-based design presents capabilities not obtainable from other CAE areas. Because it involves multidomain modeling, engineers can use model-based design to:

• Optimize the entire system with respect to the overall electromechanical architecture, and control strategy

• Perform design trade-offs for different transient and steady-state operating scenarios

• Conduct formal verification, validation, and testing including requirements traceability

• Simulate the combined digital and analog aspects of a design to determine the effects of sampling rates on system performance

• Generate code (C code, HDL, IEC 61131-3) automatically for real-time simulations of the equipment and embeddable control algorithms.

Conclusion

One of the most valuable benefits of model-based design is the time savings associated with automatic code generation. Real-time simulations of equipment let control engineers develop and test their control strategies long before actual hardware is available. Conducting this early in the development process can help all engineering disciplines involved to understand the dynamic interaction of their respective systems and have more meaningful design trade-off discussions.

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Table 1