Mechatronics: A 360-Degree View

An electronics' manufacturer needs to develop a laptop drive in less than a year. Student engineers want to build an autonomous convoy. A system integrator must design a servo system to machine medical syringes and a vendor supplies the control system for an underwater excavator.

All these scenarios share one overriding design approach: mechatronics. Whether it's a high stakes race to beat a competitor to market or a college project that paves the way to that first engineering job, the design world is fast breaking down the silos that have traditionally separated technical specialties.

To get specifics on how mechatronics is transforming engineering, Design News took a 360-degree view of the engineering universe for examples from four sectors: an OEM manufacturer, a system integrator, a vendor company and a university engineering program. What follows are their experiences in putting mechatronics to work.

Seagate: On the Road to 2 Billion

Over its 30-year history, California's Seagate Technology learned a lot about designing disk drives. It has shipped more than a billion of them in applications ranging from notebook computers to sophisticated servers for storing business data. But that doesn't make the job any easier and that's where mechatronics comes in.

“The modern hard disk drive is truly a marvel of engineering science and manufacturing,” says Monty Forehand, engineering director for Seagate's security products. “You've got to combine microscopically accurate mechanics, sub-micron read/write heads and storage media, and state-of-the-art electronics, firmware and controls systems. Then you need to bring all these technologies together in a high-volume product.”

Case in point is Seagate's Momentus 5400 FDE.2, a new encrypting hard drive that protects confidential information stored on lost or stolen PCs. Like all disk drive projects, says Forehand, the FDE.2 harnesses the skills of a broad-based team, including: mechanical, control, electronics and firmware engineering teams, plus mathematicians, physicists, materials experts and manufacturing process experts. With the new full-disk encryption (FDE) functions, the team also required cryptographers and security specialists.

One of the biggest challenges for the new 2.5-inch disk, available in capacities from 80 to 160 Gbyte, was creating a mechanical/electronic/control system capable of recording and retrieving data stored in a space of 200,000 tracks per inch. “To get an idea of the scale we work with, a single track spans only a fraction of a micron or 0.000001 meters,” says Alexander Chang, director of Advanced Drive Development. “This is roughly equivalent to a single strand of human DNA.”

Chang adds that the read/write heads on the drive literally fly above the media surface at microscopic distances. In fact, the lithography used to create the heads is a deep sub-micron design, with even finer geometry elements than semiconductor lithography.

Designed to be Rugged

Among other key features in the FDE.2, Chang points to the “G-Force Protection System.” The technology guards against damage if laptops are dropped, which can cause data loss when the head scrapes across the disk's surface. G-Force Protection senses when the system is in free-fall, moving the heads off the platter and locking them in place.

Seagate developed a control loop for G-Force that constantly monitors an accelerometer, examines other parts of the drive control system, determines when the drive is in free-fall, then decides to shut down the drive. “This development required close collaboration of the mechanical, control system, system engineering and electrical layout design teams,” says Chang. “G-Force must make a decision on disk status in a fraction of a second, yet must not be falsely tripping every second either.”

For the Seagate electronics' team, a key challenge was integrating a new ASIC onto the printed circuit card, while maintaining the same-size card and drive size, according to Vincent McGarry, senior staff systems engineer. He adds that another big job was developing the firmware required to transform a modern disk drive into a security product.

“Integration of FDE function posed challenges,” says McGarry, “since the design goal was to add this new functionality while not materially affecting the base metrics of a notebook disk, which includes power, performance, electromagnetic compliance, form-factor, interoperability and all mechanical specifications.”

The team worked hard to understand the relationship of encrypted data and the movement through the data path to the storage media. Up front in the design process, Seagate engineers also had to consider the new manufacturability factors associated with adding the FDE capabilities.

Among other issues related to integrating FDE, Forehand cites the need for a reliable source of high-quality random numbers for use by the drive in generating unknown internal keys, cryptographic challenge values and unknown nonces. “The challenge was to identify natural sources of entropy (or randomness) inside the drive and harness them for use by the system.”

This analysis of random numbers by the Security Engineering Team involved a thorough understanding of the complete underlying system — another example of a mechatronics' approach. The Security Engineering Team had to first understand the properties of the disk's mechanical, control system and electronics designs. Then the firmware and systems' engineering teams had to develop methods to capture and use the randomness in the system, as well as capture large volumes of data to analyze. Next, the cryptography and mathematics experts analyzed and validated the randomness in the data. Finally, the whole system had to be deployed for production.

In developing the FDE.2, Seagate engineers relied on a full arsenal of software tools. The team used I-DEAS from Siemens PLM for 3-D mechanical design and solids modeling, as well as ANSYS and Amperes for structural and magnetic models. They also harnessed MATLAB and LabVIEW for controls simulation and data collection analysis, while employing other simulation tools for modeling the new ASIC and other electronics components. In addition, Seagate developed several special-purpose electronics test jigs and special firmware packages for initial bring-up of the FDE-specific electronics and firmware.

“Computer tools like ANSYS are used daily to simulate deflection of the disk under shock, deflection under mechanical load and resonance modes,” says Chang. “All are simulated long before any parts are made, vastly improving development time.”

Looking back on the project, which the Seagate team completed in less than a year, Forehand emphasizes its sheer complexity demanded an interdisciplinary approach. “There is simply not enough time to develop solutions in the various disciplines and then work out all of the interactions later,” he says. “The entire disk drive system had to be considered and aligned from the outset.”

With that design philosophy entrenched at Seagate, the company has set it sights on producing its 2 billionth disk drive within the next five years.

Univ. of Florida: Tasting the Real World

Like other top engineering schools, the University of Florida implemented special programs that focus on giving students a strong dose of mechatronics' design. A key program at the graduate level, for example, is the school's Center for Intelligent Machines and Robotics (CIMAR), headed by mechanical engineering professor Carl Crane. Employing a cross-disciplinary approach, CIMAR gets masters and Ph.D. students involved in projects ranging from industrial automation to autonomous vehicles, often with the support of industry or government entities.

Vehicles designed by CIMAR's teams have reached the finals twice in recent years in DARPA's Urban Challenge, which tests the ability of autonomous vehicles to navigate city streets and other settings. Last year, Team Gator's hybrid Toyota Highlander featured such technologies as pose estimation (GPS and inertial), object detection (vision and ladar sensors) and an “Adaptive Planning” architecture that integrates planning, perception, decision making and control for the vehicle.

The Florida students are now using knowledge gained from the Urban Challenge in other projects, such as an Air Force-funded program to develop an autonomous perimeter-security vehicle capable of speeds up to 40 miles per hour. Another project incorporates infrared sensors and cameras that allow an autonomous supply truck in a convoy to follow a manned leader vehicle.

“There's growing interest in robotics projects of all sorts,” says Crane, “especially for tasks that are boring, dirty or dangerous.”

Ph.D. candidate Shannon Ridgeway says he was drawn to the CIMAR program “because most engineering problems today can't be addressed purely by a mechanical solution. You need the input from three or four disciplines and mechatronics embodies those disciplines.”

CIMAR students work with the latest 3-D modeling tools (SolidWorks and Pro/Engineer), as well as CNC machining centers and a Stratasys rapid prototyping machine. For programming, students typically use C and MATLAB. “Lower costs for vision and electronics components allow for a much better hands-on experience in engineering labs than was the case a decade ago,” says Crane.

In addition to CIMAR, the University of Florida also sponsors the Integrated Product and Process Design Program (IPPD), which over the years has attracted 1,800 senior-year engineering students in some 315 real-world projects that directly benefit industry sponsors. Each project pulls together students from different engineering disciplines, sometimes in partnership with business students and even law students specializing in intellectual property. Sponsor companies pay $20,000 per project and provide a liaison engineer to help guide the students. Companies funding projects in 2008 included Bayer, General Dynamics, Jabil, Lockheed Martin, Raytheon, Siemens and Walt Disney.

Among recent projects, an IPPD team sponsored by Harris Corp. developed a miniature hybrid power system for an autonomous vehicle that Harris uses as a research platform for its electronics products. The student design features a gasoline generator, electric starter, batteries and control electronics that combine to extend the mission of the vehicle.

While the focus of IPPD is clearly on education, Program Director Keith Stanfill says many participating students end up taking jobs with sponsor companies. “Many employers are attracted to students who've had the experience of working in projects requiring interdisciplinary skills,” he says.