Hargin B. Mechatronic system integration and design
Подождите немного. Документ загружается.
aerospace
WhitePaPer
www.mentor.com
Mechatronic systeM
integration and design
Bill hargin, Mentor graphics
Mechatronic system integration and design
www.mentor.com
2
[
5
]
aBstract
While today’s multi-discipline mechatronic systems significantly outperform legacy systems, they are also much
more complex by nature—requiring close cooperation between multiple design disciplines in order to have a
chance of meeting schedule requirements, and first-pass success. Mechatronic system designs must fluently
integrate analog and digital hardware—along with the software that controls it—presenting daunting challenges
for design teams, and requiring design processes to evolve to accommodate.
What is Mechatronic design?
The growing trend toward mechatronic system design is
driven by the same things that drive all technological
advances: the demand for higher performance and
lower costs. The word itself is a portmanteau of
“Mechanics” and “Electronics.” As Figure 1 shows,
mechatronic design includes a combination of (1)
mechanical design elements (e.g., plant, actuators,
thermal characteristics, hydraulics/fluids, and
magnetics); (2) analog, digital, and mixed-signal
electronics; (3) control systems; and (4) embedded
software. The intersections in Figure 1— (a) electro-
mechanical sensors and actuators; (b) control circuits;
and (c) digital micro-controllers—reveal the most
common areas for interdisciplinary cooperation
between mechanical, electrical, and software engineers.
Best Mechatronic design practices
Boston-based technology think tank, The Aberdeen Group, provided pivotal insight into the importance of
incorporating the right design process and tools for mechatronic system design. In a seminal study, Aberdeen
researchers used five key product development performance criteria to distinguish “Best in Class” companies, as it
relates to mechatronic design. The results were fairly revealing, and should be of significant interest within the
extended design community. In the study, Best in Class companies proved to be twice as likely as “Laggards” (worst
in class companies) to achieve Revenue targets, twice as likely to hit Product Cost (manufacturing) targets, three
times as likely to hit Product Launch Dates, twice as likely to attain Quality objectives, and twice as likely to control
their Development Costs (R&D).
Table 1: Results summary. “System Design: New Product Development for Mechatronics
Figure 1: Major elements of mechatronic design.
Mechatronic system integration and design
www.mentor.com
3
[
5
]
The fact that the Best in Class companies performed better isn’t as noteworthy as the degree to which they
performed better. Two to three times better on every variable invites the question, “How were they able to achieve
these far-superior results?”
Aberdeen’s research revealed that Best in Class companies were:
2.8 times more likely than Laggards to carefully communicate design changes ■ across disciplines.
3.2 times more likely than Laggards to allocate design requirements to specific systems, subsystems and ■
components.
7.2 times more likely than Laggards to digitally validate system behavior with the ■ simulation of integrated
mechanical, electrical, and software components.
The remainder of this article will explore these “best in class” practices in further detail.
coMMunicating design changes across disciplines
A mechanical engineer may be interested in dampening vibration by adding a stiffener. This, of course, would add
mass, and as a result may impact how fast the control system ramps up motor speed, thus impacting size
requirements on the motor, and power requirements. The benefits of immediate, formal documentation of this
design change enables concurrent, cross-discipline design.
allocation of design requireMents to specific systeMs,
suBsysteMs, and coMponents
Effective partitioning of the multiple technologies present in a mechatronic system is another significant predictor
of project success. Subsystem partitioning begins with a common-sense breakdown of the design, using Figure 1
as a high-level framework. To the degree possible, separate out Mechanical subsystems from Electrical subsystems,
and the same with Controls and Software. From there, subsystems can further be broken down into subcategories
beneath the high-level distinctions, including, for example, digital, analog, and mixed-signal electronics; divisions in
mechanical subsystems; and breaking out overlapping areas (e.g., sensors and actuators) as additional subsystems.
Next, subsystems can be assigned to
specific job functions and design groups,
and Input/Output requirements can begin
to be defined at the boundary crossings
between subsystems. Figure 2 shows the
partitioning process, moving from
Functional Design through Implementation.
With this framework in place, the design
and analysis can begin for each
subsystem—later to be combined and
analyzed as a complete system.
Figure 2: Allocation of design requirements through a top-down design process.
Mechatronic system integration and design
www.mentor.com
4
[
5
]
siMulation and Virtual prototyping
In contrast to physical prototyping, virtual prototyping and system simulation allows a system to be tested as it is
being designed, and providing access to its innermost workings at every phase of the design process. (Difficult or
impossible with physical prototypes.) Moreover, simulation provides for analysis of the impact of component
tolerances on overall system performance, which is out of the question with physical prototypes.
When employed early in the design process, simulation provides an environment in which a system can be tuned,
optimized, and critical insights can be gained – even before components are available, and before hardware can be
built. After the basic design is locked down, simulation can again be employed to verify intended system
operation—varying parameters statistically in ways that would otherwise be impossible with physical prototypes.
suBsysteM and coMponent Modeling
In order to create a model for a system, each subsystem and component in the real system needs to have a
corresponding model. These models are then stitched together (as would be their physical counterparts), to create
the overall system model. Using the Department of Defense-initiated VHDL-AMS modeling standard (IEEE 1076.1),
system integration can begin before physical hardware is available, including embedded software or any other
domain that can be described using algebraic or differential equations.
To be specific, VHDL-AMS allows expression of simultaneous, nonlinear differential and algebraic equations in any
model; the model creator need only express the equations and let the simulator solve them in time or frequency
domain. Domain knowledge from any engineering discipline can be encapsulated in reusable libraries that are
accessible by any member of the design team.
The “art” of creating these models, and knowing exactly what to model and why, are keys to successful simulation.
Some modeling tradeoffs follow:
Which system-performance characteristics are critical, and which can be ignored without affecting results? ■
Does a model already exist? ■
Can an existing model be modified? ■
What component data is available? ■
conclusion
Several software simulators exist for simulating mechatronic designs. One such simulator—SystemVision from
Mentor Graphics—supports VHDL-AMS, SPICE, and embedded C code is providing an environment in which
mechanical, electrical, software and systems engineers can collaborate using common models and a common
modeling environment. In conjunction with proper mechatronic system-design training, careful inter-discipline
communication, and deliberate system partitioning, simulation technology can play a key role in mechatronic
project success.
Figure 3: Example mechatronic system simulation from
Mentor Graphics SystemVision.
Mechatronic system integration and design
© 2009 Mentor graphics corporation, all rights reserved. this document contains information that is proprietary to Mentor graphics corporation and
may be duplicated in whole or in part by the original recipient for internal business purposes only, provided that this entire notice appears in all copies.
in accepting this document, the recipient agrees to make every reasonable effort to prevent unauthorized use of this information. all trademarks
mentioned are this document are trademarks of their respective owners.
Corporate Headquarters
Mentor Graphics Corporation
8005 SW Boeckman Road
Wilsonville, OR 97070-7777 USA
Phone: 503.685.7000
Fax: 503.685.1204
Sales and Product Information
Phone: 800.547.3000
Silicon Valley
Mentor Graphics Corporation
1001 Ridder Park Drive
San Jose, California 95131 USA
Phone: 408.436.1500
Fax: 408.436.1501
North American Support Center
Phone: 800.547.4303
Europe
Mentor Graphics
Deutschland GmbH
Arnulfstrasse 201
80634 Munich
Germany
Phone: +49.89.57096.0
Fax: +49.89.57096.400
Pacific Rim
Mentor Graphics (Taiwan)
Room 1001, 10F
International Trade Building
No. 333, Section 1, Keelung Road
Taipei, Taiwan, ROC
Phone: 886.2.87252000
Fax: 886.2.27576027
Japan
Mentor Graphics Japan Co., Ltd.
Gotenyama Garden
7-35, Kita-Shinagawa 4-chome
Shinagawa-Ku, Tokyo
Japan 140-0001
Phone: +81.3.5488.3030
Fax: +81.3.5488.3021
MGC 11-09 teCh8750-W
For the latest product information, call us or visit:
www.mentor.com
Bill hargin, Business development Manager
Bill_hargin@mentor.com
please direct any questions or enquiries to
James price, aerospace Marketing Manager
+44 1 503 310 1652
james_price@mentor.com
or contact your local sales representative
www.mentor.com/aerospace