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.
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| 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.
