Power on the go

How long does the battery in your laptop last? If you're like most people, your answer is, not long enough. That's the driving force behind the increasing interest in low-cost, efficient power sources such as better batteries and practical fuel cells. As consumer demand for portable electronic devices continues to ramp up, designers are looking at new ways to power these devices.

Lithium-ion batteries have begun to replace nickel-based chemistries such as nickel-cadmium and nickel-metal-hydride in cell phones and notebook computers. The reason: Lithium-ion cells have a low self-discharge rate, a big limitation of nickel-based batteries.

Looking past lithium-ion power, Lithium-polymer, or Li-Poly, batteries are poised to take over. Li-Poly uses the same basic chemistry but replaces the liquid electrolyte with a solid polymer. This reduces the physical size of the battery and eliminates the need for a metal casing, lowering cost. Because the polymer can remain stable through the shaping process, it can be formed into odd shapes depending on the application, possibly letting the battery become a part of the device casing itself.

Other advantages include the ability to fit in low-profile and flexible-form factors. The gelled electrolyte also weighs relatively little and there's little chance of electrolyte leakage or overcharging. Limitations for the time being include lower energy density and a higher manufacturing cost. But as demand rises, production volumes should increase and drive down costs.

Fuel cells, believe it or not, are the other contender for powering the next generation of portable electronics. Though automotive uses have gotten most of the limelight, micro fuel cells now on the drawing board will convert methanol, ethanol, or hydrogen into electrical energy and will recharge via small fuel cartridges.

Fuel cells have the potential to offer about 10 times the energy density of current lithium batteries. This means longer run times and more power for coming generations of function-rich devices.

There are still a few design problems to work out, however. One is to scale fuel cells down to a portable size and shape. Increasing operating temperatures and energy density are all hurdles yet to be overcome. Also, because fuel cells devised so far involve pressurized gas, safety considerations will be critical for the consumer market.


Storing company jewels in knowledge bases

Knowledge bases that solve particular engineering tasks could link spreadsheet calculations with company rules and design requirements.

Imagine a database that holds every idea, design rule, and the history of each product a company has turned out. Company engineers would consult it every day to learn of the company's collective experience with, for example, plastics that have good fatigue resistance or how to solve thermal problems.

It wouldn't have to be enormous because it would be constantly changing. Obsolete design rules would be omitted and new ones added as company engineers become familiar with new materials, software, technologies, and suppliers. This knowledge base would be more valuable than all the drawings in the archive because it would have the potential to recreate all earlier products and point the way to new ones, if company engineers ask the right questions.

Does your company have such a knowledge base yet? Of course not. No one does because they don't exist.

But they will. Within the next few years, the ideas and needs that have cropped up will serve as beacons for software developers, guiding them to devise knowledge databases that almost build themselves. The systems will have to work autonomously because engineers have neither the time nor inclination to pause and tell a database everything they learned that week.

Currently, modest knowledge bases are built when engineers construct 3D part models, identify certain dimensions as variables, and describe their relationships through several equations stored in spreadsheets. When it's time for a new part in a series or family, typing in a few values lets the spreadsheet drive the CAD system which builds the part. This has worked fine for individual parts and small assemblies, but it gets a little hairy when part counts approach double digits.

A recent and promising attempt at capturing knowledge starts with an engineer reading through the specification list for a new product - usually a collection of documents and initial drawings for a new design. With mostly point-and-click operations, the engineer links requirements to documents, calculates physical properties that depend on the design, and links it all into spreadsheets for additional calculations. Even Web sites can be periodically quizzed for information such as prices or delivery times.

This system has the potential to store the rationale behind decisions so future engineers know why they were made. Better yet, the system stores the knowledge, ideas, and components that went into successful designs in a reusable form.

Better ideas for storing and reusing engineering knowledge are on the drawing board. They're not here yet, but they're coming.


Mechanical drives get tough

Electromechanical drives are replacing hydraulics in aerospace, automotive, and industrial applications.

Hydraulic cylinders have long been the only choice for linear-motion applications involving high forces and speeds. But the latest electromechanical systems may offer another option.

One reason for the interest is efficiency. Hydraulics requires an electric motor or other prime mover to pump fluid to an actuator. In contrast, electromechanical systems such as ball screws and roller screws directly drive the actuator with a motor. Thus, they are generally more efficient and can be quieter, cleaner, and simpler.

The downside is that electromechanical systems come with limited force and speed capabilities. Engineers have had little choice but to accept these shortcomings, but the latest roller and ball screws are gaining ground in high-force, high-speed applications, thanks to more-optimized design of internal components and structures. Advanced software tools can now simulate the dynamic behavior of all bearing components - balls, rollers, rings, and cages - enabling design refinements that result in faster speeds, longer life, and higher load capacity.

The materials used in electromechanical systems have also gotten better, in particular, cleaner bearing steels, as well as lubrication advances and more-precise manufacturing capabilities. As a result, some of the latest electromechanical designs generate forces well in excess of 500,000 lb and offer high stiffness, shock-load resistance, zero backlash, and extremely precise positioning.

As one case in point, automakers are converting power-steering systems from hydraulic to electromechanical actuation. Electric power-steering systems eliminate the traditional power-steering pump, hoses, hydraulic fluid, and drive belt and pulley on the engine. One benefit is fewer components and speedier assembly. The engine-independent design also reduces parasitic losses, boosts fuel economy, and improves acceleration.

In a novel lift-truck application, the electromechanical system is so efficient that a regenerative circuit returns energy to the batteries when the actuators lower a load. This cuts operating costs over the life of the machine.

Finally, electromechanical drives are proving to be a good choice in demanding, continuous-duty environments where they carry heavy loads for thousands of hours in the most arduous conditions, with little or no maintenance. That's why they are making inroads into plastic-molding machinery, machine tools, medical and packaging equipment, as well as military and aerospace applications.


So much to do, so little time

One example of PLM software is SolidWorks 2003. The 3D CAD program speeds the product-design process by enabling collaboration among various departments in a company.

The saying "time is money" seems truer than ever. Delays in getting a product to market can derail its success. Well-known studies of the computer industry have found more profit in getting products out on time but over budget than late and within budget. And, at least in computers, being second may not be good enough. One report says second-to-market can only gain 70% of the leader's market share.

No question this crucial window of time keeps getting smaller. Some experts say companies have shrunk their time-to-market by as much as 50% on average in the past five years.

But this down economy may have one redeeming quality - it gives manufacturers an opportunity to rethink the way they create and manufacture products. Product life-cycle management (PLM) software is helping in this endeavor. PLM products use the Internet to enable collaboration among engineering groups that are separated geographically. This sort of keeping in touch helps speed time to market. Some reports have shown that PLM software can shorten product-development time by up to 40%. It does so by letting various departments share concepts, design files, and product specifications, as well as make changes - all in real time.

Vendors say there are advantages to breaking in PLM software when business is slow. Any rough spots probably can be corrected without harming business overall. Most importantly, these retooling efforts arm companies with more efficient product development and delivery, so they'll be well prepared for the next economic upturn. And it looks as though the idea is catching on. According to market-analysis firm Aberdeen, worldwide PLM spending is expected to jump from $3.38 billion to $5.12 billion by 2005.