Most engineers are surprised to learn that the term mechatronics is nearly 40 years old. It was first used in 1969 by Tetsuro Mori, an engineer at the Yaskawa Co., to describe a system composed of mechanical and electrical elements that is controlled by an embedded system (Figure 1 below).

In today's world it is rare to find electromechanical devices without some kind of embedded system. The intelligence from an embedded system delivers enhanced performance, reduced energy consumption, better reliability, and safer operation, which are key differentiators and value drivers for a piece of equipment.

Figure 1: Mechatronics is a synergy of mechanical and electrical systems controlled by an embedded system.

The benefits of an embedded system come at a price. As mechatronic systems take advantage of more powerful microprocessors, which provide the intelligence for embedded systems, the interaction between hardware and software becomes more complex.

Managing this complexity can prove challenging to hardware and software engineering teams, who state requirements, describe problems, and test and implement solutions in different ways.

In addition, engineers must design closed-loop control strategies to compensate for electromechanical interactions and external disturbances, as well as incorporate open-loop supervisory control for operational requirements, such as start-up and shutdown, personnel and equipment safety, and fault detection and remediation.

In most traditional design approaches, engineers test software on hardware prototypes, addressing software validation very late in the development process. Errors found in hardware or software at this stage create costly delays and may be time consuming to trace back to their root cause. Errors related to incomplete, incorrect, or conflicting requirements may even necessitate a fundamental redesign.

Model-based design
Model-based design (Figure 2 below) simplifies the development of mechatronic systems by providing a common environment for design and communication across different engineering disciplines. Model-based design extends the CAE world with an additional perspective on system-level design.

Figure 2: Model-based design places the system-level model at the center of the development process.

Just as CAD provides a geometric or static description of equipment, model-based design incorporates the dynamics and performance requirements needed to describe the system properly. Because this approach is software driven, engineers can fluidly investigate competing designs and explore new concepts without the overhead of extensive hardware investment.

Engineers can continuously test the design as it evolves, checking it against requirements and finding mistakes earlier in the development process when they are easier and less costly to correct. In addition, Model-based design automates code generation for the embedded system by eliminating the need to hand code the closed- and open-loop control algorithms.

Model-based design uses a system-level model that defines an executable specification by uniquely describing the natural and controlled behavior of the equipment in a mathematical form. Engineers can execute the model by simulating the actual dynamics and performance of the system.

The model specifies an unambiguous mathematical definition of the expected performance of the mechatronic system. As an executable specification, the system-level model provides a clear advantage over written documents, which, because they are subject to interpretation, can lead to requirements that are missing, redundant, or in conflict with other requirements.

Written requirements will always exist, but engineers can link their electronic formats to the system-level model and help establish compliance to standards such as ISO 9001 or IEC 61508.

Tracing requirements from the written specifications to the system- level model clarifies how the engineer interpreted the requirement. Electronic links between requirements and the model let engineers connect test criteria to test cases used throughout the development process.