Page 23 - The Mechatronics Handbook

power to the wheels and to control the vehicle velocity and minimize the difference between the steering
wheel direction and the direction of the vehicle motion [20,21]. In some cases, the ABS is used to slow
down the vehicle to achieve desired control. In automobiles today, typically, 8, 16, or 32-bit CPUs are
used for implementation of the various control systems. The microcontroller has onboard memory
(EEPROM/EPROM), digital and analog inputs, A/D converters, pulse width modulation (PWM), timer
functions, such as event counting and pulse width measurement, prioritized inputs, and in some cases
digital signal processing. The 32-bit processor is used for engine management, transmission control, and
airbags; the 16-bit processor is used for the ABS, TCS, VDC, instrument cluster, and air conditioning
systems; the 8-bit processor is used for seat, mirror control, and window lift systems. Today, there are
about 30–60 microcontrollers in a car. This is expected to increase with the drive towards developing
modular systems for plug-n-ply mechatronics subsystems.
Mechatronics has become a necessity for product differentiation in automobiles. Since the basics of
internal combustion engine were worked out almost a century ago, differences in the engine design
among the various automobiles are no longer useful as a product differentiator. In the 1970s, the Japanese
automakers succeeded in establishing a foothold in the U.S. automobile market by offering unsurpassed
quality and fuel-efficient small automobiles. The quality of the vehicle was the product differentiator
through the 1980s. In the 1990s, consumers came to expect quality and reliability in automobiles from
all manufacturers. Today, mechatronic features have become the product differentiator in these tradition-
ally mechanical systems. This is further accelerated by higher performance price ratio in electronics,
market demand for innovative products with smart features, and the drive to reduce cost of manufac-
turing of existing products through redesign incorporating mechatronics elements. With the prospects
of low single digit (2–3%) growth, automotive makers will be searching for high-tech features that will
differentiate their vehicles from others [22]. The automotive electronics market in North America, now
at about $20 billion, is expected to reach $28 billion by 2004 [22]. New applications of mechatronic
systems in the automotive world include semi-autonomous to fully autonomous automobiles, safety
enhancements, emission reduction, and other features including intelligent cruise control, and brake by
wire systems eliminating the hydraulics [23]. Another significant growth area that would benefit from a
mechatronics design approach is wireless networking of automobiles to ground stations and vehicle-to-
vehicle communication. Telematics, which combines audio, hands-free cell phone, navigation, Internet
connectivity, e-mail, and voice recognition, is perhaps the largest potential automotive growth area. In
fact, the use of electronics in automobiles is expected to increase at an annual rate of 6% per year over
the next five years, and the electronics functionality will double over the next five years [24].
Micro Electromechanical Systems (MEMS) is an enabling technology for the cost-effective develop-
ment of sensors and actuators for mechatronics applications. Already, several MEMS devices are in use
in automobiles, including sensors and actuators for airbag deployment and pressure sensors for manifold
pressure measurement. Integrating MEMS devices with CMOS signal conditioning circuits on the same
silicon chip is another example of development of enabling technologies that will improve mechatronic
products, such as the automobile.
Millimeter wave radar technology has recently found applications in automobiles. The millimeter wave
radar detects the location of objects (other vehicles) in the scenery and the distance to the obstacle and
the velocity in real-time. A detailed description of a working system is given by Suzuki et al. [25]. Figure 1.4
shows an illustration of the vehicle-sensing capability with a millimeter-waver radar. This technology
provides the capability to control the distance between the vehicle and an obstacle (or another vehicle)
by integrating the sensor with the cruise control and ABS systems. The driver is able to set the speed and
the desired distance between the cars ahead of him. The ABS system and the cruise control system are
coupled together to safely achieve this remarkable capability. One logical extension of the obstacle
avoidance capability is slow speed semi-autonomous driving where the vehicle maintains a constant
distance from the vehicle ahead in traffic jam conditions. Fully autonomous vehicles are well within the
scope of mechatronics development within the next 20 years. Supporting investigations are underway in
many research centers on development of semi-autonomous cars with reactive path planning using GPS-
based continuous traffic model updates and stop-and-go automation. A proposed sensing and control

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