Hydraulics gets better with age

Moog's PowerShot injection system combines servomotors and hydraulics in one module.

Proponents of electric drives have their sights set on the hydraulics market. But it's also a fact that hydraulics is quietly evolving to better serve existing markets and tackle new ones.

One contributor to this trend is sealing technology, which has advanced by leaps and bounds. Today's actuators run for millions of cycles with little or no maintenance and leakage. New material formulations - for instance, perfluorinated elastomers that offer broad chemical and temperature resistance - meet the most demanding static, dynamic, and environmental applications. And tools such as FEA software specifically tailored for elastomeric analysis let engineers design and predict a seal's performance in a variety of media, temperatures, and pressures before the part is ever installed.

Another change is a growing interest in hydraulic systems that don't use oil. Water-hydraulic systems are ideal when safety or cleanliness is of utmost concern. Inherently environmentally friendly, water-based systems can be more efficient than their oil counterparts, and water is readily available, inexpensive, nonflammable, and easy to dispose of compared with waste oil. Development of sophisticated corrosion-resistant materials, in particular polymer coatings that overcome potential lubrication problems on seals and sliding surfaces, are paving the way to more widespread use.

Getting the most from hydraulics - whether water or oil based - requires sophisticated electronic controllers capable of precise servocontrol. Unlike primitive controls of the past, the latest versions provide, for example, pressure and position control, separate gains for each direction of motion, and valve-deadband compensation. Sophisticated algorithms eliminate motion discontinuities and jerkiness, and better modeling tools make it easier to program motion sequences as well as predict and optimize performance.

Advanced controls already permit previously unheard of applications. For instance, earthmoving equipment now melds mobile hydraulics with global-positioning systems in revolutionary grade-control systems. GPS signals modulate the hydraulics and, in turn, the blade position on a grader or dozer to automatically control grades and surface contours. And as microprocessors improve, next-generation hydraulic controllers coupled with cutting-edge position transducers should produce 10-µm resolution in industrial applications.


Easing traffic with technology

Commuters in Los Angeles, New York and Chicago each spend about 110 hr sitting in traffic jams annually. Nationwide, congested traffic costs the U.S. over $100 billion in lost productivity, which doesnt include wasted gas, prematurely aged cars and trucks, and dirty air. Building new highways doesnt seem to help. They're gridlocked almost as soon as they're complete.

One set of solutions is Intelligent Transportation Systems (ITS). They combine computers, communications, sensors and control, navigation, and electronics to get the most out of our current infrastructure. Automakers, for example, have already started putting ITS devices in luxury cars, hoping consumer demand will spread and mass production will make them more affordable. GPS-based navigation systems and back-up warning systems, for instance, can be found in many high-end sedans.

Highway planners are also taking note of ITS. Together with local and state transportation officials, they've set up hundreds of pilot projects to assess the current situation and test emerging technologies.

In Virginia, for example, researchers remotely monitor a 30-mile stretch of highway around Washington, D.C., with loop detectors embedded every 0.5 miles in the roadway (550 in total) and 45 closed-circuit TVs. Twenty-six on and off-ramp meters measure congestion patterns while over a hundred variable-message signs send drivers information on local traffic.There are also more safety systems being planned for tomorrow's commercial trucks and consumer vehicles. Lane-departure systems, for example, use video-based image processing to track lane markings.

Eventually, futurists see smart vehicles and intelligent highways converging into a more integrated transportation system. They envision roads that "steer" cars and trucks, keeping traffic moving rapidly and safely. Roads could also monitor themselves, reporting conditions such as snow, rain, and ice in real time to drivers and highway managers.


Servocontrol: The next generation

Third-generation servodriven machines often feature modular construction that simplifies manufacturing and product changeovers. An example is the recently developed FLM 4080 liquid filler from Bosch Packaging Technology, Minneapolis. The base unit is a standard design that rarely changes, but many parts of the machine get specially configured depending on the customer. These include the controls, infeed/outfeed equipment, and pumping systems.

Here's a no-brainer strategy for boosting productivity on a manufacturing line. First junk the mechanical line shafts that drive individual operations via belts or geartrains. Then add as many brushless servomotors as necessary to run each operation with a precision unmatched by strictly mechanical means. The benefits of this servopowered approach: There is usually little maintenance involved, the better precision generally wastes less raw material, and production often speeds up to boot.

An emerging truism is that the better the coordination among servos, the more productive the machinery. In a nutshell, the technology pays off best when servos operate together in a meaningful way.

A typical example: Coordinating upstream manufacturing functions with those downstream, so that all parts of the line produce work just fast enough to keep downstream operations busy. This eliminates the need for mini-inventories of work-in-progress between manufacturing stations.Advances in controls and industrial networking now make such scenarios practical even on a budget. In addition, the trend toward interoperable controls has simplified the task of integrating servosystems with production equipment.

The term coined to describe such servopowered equipment is third generation, Gen3 for short. The biggest contributor to making Gen3 possible is industrial networking architecture that combines distributed intelligent motor drives with centralized controllers. But it has only become feasible recently with the advent of sufficiently speedy industrial networking.Besides speedy networking, another factor characterizing Gen3 architectures is the integration of logic and motion control in the same program.

Manufacturers say the resulting code can be less than half as long as older techniques required to accomplish the same functions. Moreover, use of these standards promotes interoperability among different brands of controllers and servos. This comes in handy when installing equipment in various parts of the world where customers prefer to use controls and other components from local suppliers.


There's a new tag in town

ExxonMobile Speedpass users can now buy gasoline, and hamburgers, by simply pointing their RFID-loaded keyrings at readers inside McDonald's.

From tracking cattle to trailing prison inmates, radio-frequency identification (RFID) has seen its share of successes. New advances are in the works to make this technology ever more pervasive.

Today's RFID tags, usually made up of large ICs and wired or etched-copper antennae, cost from 50 cents on up. Some industry experts say new technologies and manufacturing processes will soon bring the five-cent tag. Tags at that price point are looked upon as something of a holy grail: Manufacturers, retailers, and consumers would benefit hugely if the goal were met.

Working hard to unleash the first of these tags is the Massachusetts Institute of Technology's AutoID Center. MIT's plan is grounded by five key elements. Electronic Product Codes (EPC), which identify each distinctive item, manufacturer, product, version, and serial number; ID systems (radio-frequency readers and tags); an Object Naming Service, which tells computers where to find information on the Internet about products with EPCs; a Physical Markup Language similar to HTML; and software technology called Savant that manages and moves the information around the EPC network (for more details, see MD, 11/07/02, pg. 73).

Though the AutoID Center has work to do before realizing any sort of global-tracking system, there have been significant strides toward cheaper tags and readers. For instance, one partner has created a novel assembly technique, called Fluidic Self Assembly (FSA), for attaching chips to plastic substrates. AutoID Center researchers say such bulk processing methods have potential for high yield, low costs, and scalability to massive volumes. The Center is currently testing its RFID system in phases with help from major manufacturers and retailers.

Though most industry experts agree the AutoID Center has done a lot to get the RFID ball rolling, not all are as optimistic as the Center that the five-cent tag is within reach. Some leading RFID technology providers believe the high cost of materials and manufacturing is still the biggest prohibiting factor. But as they are quick to point out, RFID technology is already finding a place in the market. For example, millions of people use the ExxonMobile Speedpass cashless payment system with technology from Texas Instruments (TI) to buy gasoline at the pump and make other purchases. Those same Speedpass users can now point their RFID-loaded keyrings at readers inside select McDonald's restaurants and at their drive-thru windows. The system automatically bills fast-food purchases to customers' credit or check cards.