[FoRK] the end of M.E.

Eugen Leitl eugen at leitl.org
Thu Jun 9 13:15:19 PDT 2005


 the end of the m.e.?

 They call this "convergence." Old lines are changing, or disappearing
 altogether. What it's doing under the hood is downright electrifying.
 by Peter W. Huber and Mark P. Mills 	

 The turf still divides up quite neatly. The electrical engineers move the
 light stuff—electrons, power, bits, and logic. The mechanical engineers
 do the heavy lifting; they move atoms. And, like it or not, the MEs still
 control most of the real estate.

 Look at our cars. They're made of big heavy things that shake, bounce, and
 sway; they're propelled by pistons, shafts, gears, and belts; controlled by
 shafts, gears, valves, and hydraulic fluids. All the really important parts
 go click-click, bang-bang. The car is a 100 kW (peak) machine. The stuff
 that hums instead of clanking, the electric load, peaks at 2 kW.

 Mechanical engineers control most of the rest of our energy economy, too.
 The United States consumes 100 quadrillion Btus, or quads, of raw thermal
 energy every year, in three broad sectors—electric power,
 transportation, and heat—with consumption split (roughly) 40-30-30 among
 the three. But electric power plants themselves are mainly thermomechanical:
 The furnaces, boilers, and turbines themselves consume over half of the
 fuel; only about 16 quads worth of mechanical energy actually get to the
 shafts that spin the generators that dispatch the gigawatt-hours.

 [Image: Komatsu's 930E is a 2,000 kW truck. A 16-cylinder diesel engine drives a
 generator that powers electric motors on the wheels.]

 It doesn't have to be that way, and pretty soon it won't be. General
 Electric's 4,400-horsepower, diesel-electric GEVO-12 locomotive is powered
 by an enormous, diesel-fueled engine-driven generator; everything beyond is
 electric. Komatsu's 930E—a monster mining truck with 320-ton
 capacity—is propelled by a 2-megawatt Detroit diesel-electric generator.
 Everything else, right down to the 12-foot wheels, is driven electrically.
 Submarines have been largely all-electric for decades, and the surface ships
 now on the Navy's drawing boards are all-electric, from the propeller to the
 guns. Thermomechanical engines are still the prime movers on all of these
 platforms, but what they move is electricity. An on-board generator powers
 an all-electric drivetrain; an electric motor drives the propeller or

 Electric drives are taking over because an electrical bus can convey far
 more power in much smaller, lighter conduits, and do it far more precisely
 and reliably, than even the best designed mechanical drivetrain. Indeed, on
 the key metrics of speed and power density, the electrical powertrain is
 about five orders of magnitude better. Electricity moves at close to the
 speed of light; all thermal and mechanical systems move at the speed of
 sound, or slower. It takes 10,000 driveshafts in 10,000 redlining Pontiacs
 to convey about as much power (1 gigawatt) as a single power plant
 dispatches down a few dozen high-voltage cables. By a very wide margin,
 electricity is indeed the fastest and densest form of power that has been
 tamed for ubiquitous use.

 But precisely because it is so fast and dense, electricity is inherently
 difficult to control. Direct-drive electrical systems are fast all right,
 but they tend to jitter, overshoot, jerk out of control, and fall off the
 edge. The solution, historically, has been to get mechanical again—wrap
 the electric coils and magnets around heavy, inertial, and frictional
 components to get back to a simple and steady source of mechanical
 power—rotating a shaft, say—which can then be channeled through
 gears, belts, hydraulic fluids, and other arrays of click-click, bang-bang
 logic well before it reaches the final payload. Until recently, direct-drive
 electrical movers—systems in which the power stays electric right down
 to the very threshold of payload—have remained the exception, not the

 Power in Control

 But big motors and their electric power supplies can now be built compact
 and precise enough to mimic the small muscles of a hand. A key breakthrough
 occurred in 1982, when Hans Becke and Carl Wheatley (both at RCA) were
 granted a patent for what is now called the insulated gate bipolar
 transistor. IGBTs are high-power semiconductor gates. They control kilowatts
 almost as efficiently as logic semiconductors control the picowatts that we
 call bits.

 Sensors have also become sufficiently small, fast, and accurate to provide
 real-time feedback of what's happening at the payload. And cheap
 microprocessors are now readily available to make sense of it all, and to
 constantly recalculate how much power to dispatch to the drive to make it do
 exactly what's needed.

 Supplied with a suitably shaped and amplified stream of power, a loudspeaker
 vibrates a diaphragm through a Beethoven symphony; do the same with a
 hundred kilowatts, and you can run a Pontiac. What's new now is that
 inexpensive semiconductors are available to provide the extraordinarily
 precise control of very large amounts of electric power, at very low cost,
 in very compact controllers.

 The sidestick, being tested by Mercedes-Benz, is part of a fully
 computer-controlled car handling system of the possibly near future.

 Because they move less material in the middle, direct-drive powertrains have
 far less inertia and friction; and because they are informed by very fast
 sensors controlled by computers they can react much faster to the outside
 world. Direct-drive motors can thus reach levels of precision that are
 completely unattainable with any conventional technology. With less weight
 in the powertrain, and fewer moving parts, direct-drives are also more
 robust. Pneumatic and hydraulic fluids leak, turn into molasses when they
 get cold, and are easily contaminated. Shafts, belts, and pulleys need
 lubricants, and get bent out of shape when they expand or contract. They
 corrode and need periodic maintenance. Electric wires don't.

 The transformation is already well under way in the car's peripheral
 systems. The belts and pulleys that drive water and oil pumps, and radiator
 cooling fans, are giving way to electric motors. The best brakes are already
 electrohydraulic; all-electric brakes will follow. With electronic
 throttles, the gas pedal sends electrical instructions to a microprocessor
 that controls the fuel injection system electronically. Drive-by-wire
 electric power steering began appearing in production vehicles in 2001.
 Passive, reactive, energy-dissipating springs and shock absorbers are being
 displaced by an active array of powerful linear motors that move wheels
 vertically as needed to maintain traction beneath and a smooth ride above.

 And electric actuators will displace the steel camshaft on every valved
 engine. Put each valve under precise, direct, digital-electric control,
 actuated independently by its own compact electric motor—open and close
 each valve as dictated by current engine temperature, terrain, load, and
 countless other variables—and, in effect, you continuously retune the
 engine for peak performance. Belts, shafts, and chains melt away. Everything
 shrinks, everything gets lighter, and every aspect of performance

 To meet this steadily rising demand for electric power, car manufacturers
 are making the transition to a 42-volt grid to replace the existing 14-volt
 grid. Lower-voltage wires just can't convey large amounts of power
 efficiently. A new 42-volt industry standard emerged recently, and half of
 global automobile production will be on a 42-volt platform within the next
 decade or so.

 Next-generation integrated high-power alternator/starter motors have already
 been incorporated in BMWs and Benzes, and in Ford and GM trucks; about half
 of all new cars will have them by 2010. These units will supply the car with
 abundant, efficiently generated electric power, in a much lighter package,
 that will provide a virtually instant engine start as well.

 Cheap in the Gearbox

 This will set the stage for the last big step—the one already taken in
 monster trucks: Silicon and electric power will knock out the entire
 gearbox, driveshaft, differential, and related hardware; electric drives
 power the motors that turn the wheels. Power chips now make it possible to
 build high-power motors the size of a coffee can, and prices are dropping
 fast. When such motors finally begin driving the wheels, the entire output
 of the engine will have to be converted immediately into electricity before
 it is distributed, used, or stored throughout the car. It will take
 heavy-duty wiring and substantial
 silicon drives and electric motors to propel a hybrid-electric sport utility
 vehicle down a highway at 70 mph—but they'll be far smaller than the
 steel structures in today's powertrain. Cars will shed many hundreds of
 pounds, and every key aspect of performance will improve considerably.

 As this process unfolds, the engineering focus will shift inexorably toward
 finding the most efficient means of generating electricity on-board. Trains
 and monster trucks both use big diesel generators. Hybrid cars on the road
 today burn gasoline, but it's the fuel cell that attracts the most attention
 from visionaries and critics of the internal combustion engine. Remarkably
 elegant in its basic operation, the fuel cell transforms fuel into
 electricity in a single step, completely bypassing the furnace, turbine, and
 generator. In this scenario, mechanical engineering ultimately surrenders
 its last major under-the-hood citadel to chemical engineers.

 Much the same transformation is well under way in the factory. The
 19th-century factory was powered by a single driveshaft spanning the length
 of the building; belts and chains delivered power to each individual work
 bay. That primary mechanical driveshaft gave way to electric power long ago,
 with motors powering the lathe, drill, or milling machine in each
 workstation. But, by and large, the motors still connect to shafts and belts
 and compressors. As in the car, mechanical systems still control the last
 few meters of the powertrain.

 I, Sensitive Robot

 The new industrial robots, however, are complex configurations of electric
 servo motors; the electric power now runs right to the final threshold of
 where the power is needed. Packed with sensors, the robots are now precise,
 sensitive, and far more compact than any mechanical alternative. They are
 also far more flexible—they now can be instantly reconfigured to perform
 new tasks through software alone, a dramatic advance over previous systems
 that required hours of manual rewiring.

 At the same time, high-power lasers—built around another family of
 recently developed semiconductors—are rapidly taking over functions
 previously viewed as mechanical. At kilowatt and megawatt power levels,
 lasers don't move bits, they move material. They fuse powdered metals into
 finished parts, without any machining, cutting, or joining. They supply
 ultra-fine heating, soldering, drilling, cutting, and materials processing,
 with fantastic improvements in speed, precision, and efficiency. They create
 thermal pulses that can blast metals and other materials off a source and
 deposit them on a target to create entire new classes of material coatings.
 They move ink in printers—not just desktop devices, but also the mammoth
 machines used to produce newspapers. They solder optoelectronic chips
 without destroying the silicon real estate around them, and they supply
 unequaled precision in the bulk processing of workaday materials—heat
 treating, welding, polymer bonding, sintering, soldering, epoxy curing, and
 the hardening, abrading, and milling of surfaces.

 Delphi has sold millions of its electric power steering units, which
 eliminate hoses, pump, and hydraulic fluid.

 Mechanical systems can be remarkably clever—just look at how a high-end
 mechanical watch powers and times the movement of hands around the watch
 face. In engines and machines of every description, much of the mechanical
 engineering is still devoted to imposing a desired logic on the flow of
 power. Until quite recently, EEs themselves relied on at least
 semi-mechanical systems to choreograph and order the flow of electricity.
 The huge electromechanical switches that phone companies used to route calls
 until the 1960s set up circuits by reconfiguring tapestry-like arrays of
 small, electromechanical switches—thousands and thousands of them,
 clicking away, day and night. But the advent of the transistor—invented
 by Bell Labs—changed all that. Semiconductors now choreograph the flow
 of all-electric
 (or photonic) power through our watches and our phone lines.

 Pushing semiconductors up the power curve took 20 years longer than it did
 to push them down. But it has now been done. And these fundamentally new
 technologies of "digital power" make possible an extraordinary new variety
 of compact, affordable, product-assembling, platform-moving, people- moving,
 and power-projecting systems that seem to be all but magical. They will
 inevitably infiltrate, capture, and transform the capital infrastructure of
 our entire energy economy—the trillions of dollars of hardware that
 convert heat into motion, motion into electricity, and ordinary electricity
 into highly ordered electron and photon power.

 One might say that the age of mechanical engineering was launched by James
 Watt's steam engine in 1763, and propelled through its second century by
 Nikolaus Otto's 1876 invention of the spark-ignited petroleum engine. We are
 now at the dawn of the age of electrical engineering, not because we
 recently learned how to generate light-speed electrical power, but because
 we have now finally learned how to control it.

 Peter W. Huber, a former mechanical engineering instructor at MIT, is a
 senior fellow of the Manhattan Institute. Mark P. Mills, a physicist, is a
 founding partner of a venture fund, Digital Power Capital. They are
 co-authors of The Bottomless Well (Basic Books, 2005) . 

Eugen* Leitl <a href="http://leitl.org">leitl</a>
ICBM: 48.07100, 11.36820            http://www.leitl.org
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