December 06, 2010
Addressing the Challenges of Mechatronics: The Future of Mechanical Design
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There was a time when mechanical systems and products were strictly mechanical, however, those days are rapidly coming to a close as products continue to become more capable, but complex. These increasingly sophisticated products are virtually guaranteed to employ mechatronics to at least some degree. So, what exactly constitutes mechatronics? It is a term that has different definitions that will be explored, but the design methodology for realizing mechatronics is basically the same regardless of definition.
Mechatronics is the integration of electrical and electronic components into mechanical enclosures and/or mechanical subassemblies. Examples include multi-function printer/scanner/fax machines, digital music players, laptop and desktop computers, digital cameras, cell phones, and home appliances. All of these types of products include electronic systems that are a synergistic integration and packaging of electrical and mechanical subsystems. Although the consumer electronics industry is typical of this description of mechatronics, it could also include products from a broader cross section of industries, including commercial test equipment, for example.
Another way to define and view mechatronics is as a subset of the electronics industry where mechatronic systems are comprised of a systematic integration of mechanical, electrical, electronics, and embedded firmware (software) components. When all of the various components are combined the result is an electromechanical system. In this context, mechatronics is characterized by software and electronics controlling electromechanical systems. This definition is best exemplified by modern automotive engines and other automotive systems, aerospace equipment, and complex production machinery.
In another sense, mechatronics is actually a methodology used for achieving an optimal design solution for an electromechanical product. Key mechatronics ideas are developed during the interdisciplinary simulation process that provide the conditions for raising synergy and providing a catalytic effect for discovering solutions to complex problems. The synergy arises from the integration of mechanical, electrical, and computer systems with information systems for the design and manufacture of mechatronics products. In other words, many different distinct subsystems coming together to perform a complex function. A good example of this would be just about any machine used for production
ranging from automotive tires to food processing.
Mechatronic products exhibit performance characteristics that were previously difficult or impossible to achieve without a synergistic approach. The key elements of the synergistic approach are shown in the figure that illustrates that mechatronics are the result of applying information systems to mechanical, electrical, and computer systems.
Regardless of the particular definition, all mechatronic systems are excellent candidates for design process optimization due to the high complexity of mechatronic designs, the high degree of integration of electrical, mechanical, and information-processing components. However, it is integrating all of these components that presents the biggest challenges to the design team and their choice of design tools for successfully creating complex mechatronics systems.
The Challenges of Mechatronics
There are a number of critical business issues associated with mechatronics that affect both the engineering/design team and the management team. These issues include everything from improving product quality to reducing costs to shortening the product development cycle with faster time to market to sustainability and RoHS. These issues translate into pressures to produce increasingly complex products that are superior to previous or competitors' products in less time at less cost. One of the most effective ways to reduce cost has proven to be in reducing the number of physical prototypes during the product development cycle in favor of digital test and simulation as an integral part
of the digital design phase.
As mechatronic systems get more complex, the challenges associated with successfully executing them also become more demanding. For example, greater end-user functionality and capability requires greater numbers of electronic components necessitating denser electronic component packaging. As electronic component density increases, cooling requirements also increase. Heat transfer is becoming more challenging as packages become more dense causing more heat failure, which ultimately becomes a quality issue that must be addressed. During the design phase, denser packaging then becomes a critical system issue due to the interoperability requirements between electronic CAD (ECAD) and
mechanical CAD (MCAD) software applications.
A trend that is increasingly evident is that as mechatronics systems get more complex and as functionality demands increase, in many instances software and firmware are replacing or at least supplementing hardware. A benefit of this transition from hardware to the burgeoning emphasis on software is called “Postponement,” that is, the ability to include major functionality features during the final stages of production enabled by embedded software system.
The Mechatronics Design Process
Mechatronics systems present major design and production challenges because they have to bring together many different types of physical and digital parts, processes, and personnel to create a successful end product. Designing and producing a mechatronics system requires a well-orchestrated effort by many types of people in a wide variety of job roles and functions - everything from industrial design to PCB layout to control logic design to production planning.
Although all mechatronics systems are different, they all share the same basic six process elements that will next be discussed. These six elements are what take a mechatronics system idea through design, production, and ultimately the marketplace.
Preliminary Specification and Definition
Before any product is designed, several criteria must be established, including market feasibility, ensuring that the proposed product fulfills a genuine need. If feasibility and need are determined to be worth the risk of designing and marketing the product, then anticipated preliminary cost and proposed profit margin are defined.
Once upper management is satisfied with its potential financial success, the functionality and performance specification of the proposed product is defined with functional system requirements that will serve as general blueprint on all functional levels for moving ahead. During this phase, and to ensure that the functional requirements are met, components and materials are specified, and manufacturing processes are defined.
Packaging Design - Modeling and Simulation
The packaging design phase is really where the principles and challenges of mechatronics are first encountered, but are assisted with digital modeling and simulation techniques. These techniques are employed up front to minimize the cost and time required for producing the final physical end product that is the result of this whole endeavor. At this stage, a diverse group of design professions engage to work cohesively as a collaborative team in their respective disciplines. Industrial design (conceptual and aesthetics); mechanical engineering (conceptual, functional, manufacturing considerations); interaction design (software-hardware control interface); and electrical/electronic
engineering (functional, power requirements, insulation/shielding).
Simultaneously, preliminary printed circuit board (PCB) layout and rough 3D mechanical CAD model are generated with major components and interconnections defined. All collaborative team members constantly check the availability of standardized 3D components to reduce cost. Historically, this stage has encountered problems due to a lack of interoperability between ECAD and MCAD resulting in duplication of effort. However, with greater use of digital modeling and simulation from the outset has assisted with interference detection (chips and other components on PCB) and routing - discrete wire, cable harnesses, ribbon cables, and connectors between the various mechanical and electrical
subsystems. The packaging design phase is the first of many to come where design optimizations are performed for all components - mechanical, electrical, electronic, software, etc.
Generally, and beyond pure electronic functionality, PCB layout begins with constraints imposed by mechanical considerations via the Intermediate Data Format (IDF). The IDF is a neutral format for exchanging PCA (Printed Circuit Assembly) information between PCB layout design (ECAD) systems and mechanical CAD systems. IDF was originally developed in 1992 and has evolved ever since. An IDF file is actually two files. The first file contains information about the physical characteristics of the PCB, while the second file contains information about the size and shape of each of the components on the PCB.
Once the ground rules have been established, with an ECAD system, a preliminary circuit trace layout is created that indicates “keep out” areas, as well as the locations for plated and non-plated holes for component placement. Electrical/electronic design optimizations are performed to confirm component selection and placement, circuit traces for power and ground considerations, and general circuit logic. After one or more iterations, a refined layout with components is transferred back to the mechanical engineer via IDF for checking against the preliminary packaging design for proper fit.
While MCAD software is getting easier to use, ECAD software ironically is getting harder to use and more specialized because of the rapid changes occurring in the semiconductor industry - generally regarded as occurring faster than on the mechanical side of the house.
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-- Jeff Rowe, MCADCafe.com Contributing Editor.
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