Mechatronics transforms driving experience

Using computer control over the previously mechanical system entails fewer and less-expensive components to outperform tight-spec mechanically calibrated components.

The seminal mechatronics example is the hard disk drive. Prior to disk drives, computer mass storage was managed on computerized tape drives that merely automated the open-loop functions of a manual tape drive and, thus, did not constitute mechatronics.

But the hard disk drive delivers more than the sum of its parts by applying closed-loop control to a new style of mechanical device that would not have been possible without electronics, and, thus qualifies it as mechatronics. A disk drive uses a rotating disk instead of a reel of tape, extracting new levels of performance from the mechanical storage media by randomly accessing any sector on the disk.

The mechatronics of the drive also demonstrates the long-term effect ex- pected from automating other mechanical devices. As the hard disk evolved from hubcap-sized to mini to micro, the credit for its shrinkage can be equally bestowed on members of interdisciplinary teams of electronics, mechanical and materials engineers. By designing ever-faster electronics, tinier disk-head positioning mechanisms and denser storage materials, you can buy a thumb-sized hard drive on a compact-flash-sized card that can fit in your digital camera. Yet, it's cheaper than purely electronics cards.

Beyond cars

Today a worldwide push is on to bring mechatronics into every design. Yet the modern car remains the technology's best example. One of the first subsystems to be automated was the formerly purely mechanical carburetor, which now uses a computer-controlled fuel injector.

During cold-engine startup, automated fuel injectors adjust fuel-air mixtures in real-time. Mechatronics didn't just add motorized controllers to a carburetor--like the automated tape drive--but used new materials, the fuel injectors, to handle the old functions better.

Nearly every aspect of mechanical devices are being modernized with varying degrees of mechatronics--usually embedding microcontrollers to read sensors, then con- sulting their preprogramming and responding by actuating the servos that formerly reacted to mechanical timing signals.

In cars, the last frontier is "drive by wire," in which steering is automated, effectively allowing a computer to drive.

"Many drivers do not even realize that drive-by-wire technology is built in; for instance, almost all hybrid electric vehicles deploy drive-by-wire technologies because of the needs of the hybrid synergy drive," said Williams.

Automotive OEMs that have introduced drive-by-wire technology include BMW, Mercedes-Benz, Audi, Porsche, Lamborghini, Ferrari, Jaguar, Volvo, Subaru, Lexus, Volkswagen and Toyota.

Besides outperforming purely mech- anical components and subsystems, mechatronics offers easy reprogrammability to refine functionality as well as capabilities, such as automated parallel parking, impossible for purely mechanical devices. New product categories also have been defined by mechatronics: from the seminal disk drive to digital-light processors to microelectromechanical systems. n