Oh, That's Near Enough

The Economist Technology Quarterly June 2nd 2012 Monitor 1 Contents On the cover Robots are playing an increasingly important role in warfare on land, at sea and in the air. But as they become smarter,more capable and more deadly, they are raising dicult ethical quandaries about the extent to which they should be able to make their own decisions, page 11 Oh, that’s near enough Monitor 1 Sloppy microchips, smarter irrigation, a new twist on robot arms, greener brick kilns, recycling washing enzymes, keeping oil pipes clear, peer•to•peer technical support, Computing: Letting microchips make a few mistakes here and there could wooden batteries, tness for gamers and the joys of make them much faster and more energy•ecient zoomable interfaces ECADES of manna from heaven. faster and more energy•ecient. DThat is how Trevor Mudge, a comput• The important thing is to control where Di erence engine er scientist at the University of Michigan, the errors occur. Masahiro Fujita, who is 8 Talking trash Ann Arbor, describes the technological designing sloppy chips at the University How waste incinerators have impact of the steady doubling, roughly of Tokyo, notes that a single mistake at the cleaned up their act every two years, of the number of transis• beginning of a sequence of instructions tors that can be crammed onto a silicon can propagate through subsequent calcu• Robots go to war chip. It has increased the processing power lations and completely mess up the be• 9 On the march and storage capacity of computers while haviour of a computer or robot. But, he How far should robots be allowed reducing their size and energy consump• says, even relatively numerous mistakes to go on the battleeld? tion. The results are all around us. But this are no big deal in other circumstances, steady doubling (known as Moore’s law such as when handling sound, images or Acoustic microuidics after Gordon Moore, the engineer who video. Tiny sound distortions or slightly rst pointed it out in 1965) cannot go on for miscoloured pixels will go unnoticed. 11 A sound idea ever, and nearly ve decades later the An international team of researchers at Manipulating droplets of uid limits may nally be within sight. Rice University in Houston, Texas, the using sound has many uses Transistors now measure as little as 22 Swiss Centre for Electronics and Micro• nanometres (billionths of a metre) in technology (CSEM) in Neuchâtel and Inside story width, smaller than the wavelength of Nanyang Technological University in 13 Hot stu light with which they are etched, and just Singapore found that by reducing the What should be done with a few tens of atoms across. As transistors operating voltage, sloppy chips could high•level nuclear waste? get smaller, keeping them cool and error• deliver equivalent performance to ordin• free becomes more dicult. Lowering the ary chips using a quarter of the energy. For Open•source medical devices voltage at which transistors operate pro• audio playback, the researchers found, 15 When code can kill or cure duces less heat, but further reductions are sound quality was acceptable even with An open•source approach could now dicult because feebler voltages error rates of 8%. boost safety and innovation result in more frequent errors. The march Hearing aids or mobile phones should towards ever•smaller and faster chips is let people trade sound quality for battery Brain scan starting to come unglued, says Dr Mudge. life, says Krishna Palem, the head of the 17 Burt Rutan That is why he and other computer scien• project. When the battery is running low, A prole of the maverick tists are taking a new approach: designing they could switch to a high•error mode aeronautical engineer microchips that can tolerate errors in their and put up with the static. A prototype operation. Such inexact or sloppy chips, sloppy chip, developed with funding from as they are also known, can be smaller, Intel, the world’s largest chipmaker, and 1 2 Monitor The Economist Technology Quarterly June 2nd 2012 2 America’s Department of Defence, is now called asymmetric reliability, uses ready for production. Dr Palem plans to error•prone circuits for number crunching establish a start•up to sell such chips for to save power and run faster, says Sub• use in hearing aids with long battery lives. hasish Mitra, a computer scientist at Stan• Dribbles and bits Another trick is called pruning. ford University. Conventional circuits are Chips are wired so more power is deliv• then used to spot and weed out unaccept• ered to more important areas, while areas able errors. His work is funded by Ameri• that compute non•essential data (or are ca’s Department of Defence and compa• infrequently used) are given less power or nies including Bosch, Cisco, Inneon, Agriculture: A new smart irrigation simply removed altogether. Tests at CSEM Intel, Semiconductor Research Corpo• system, based on detailed mapping, by Avinash Lingamneni found that ration, Samsung and Texas Instruments. can save water, cut costs and reduce pruned circuits were twice as fast, con• With this technique, the mechanics of sumed half as much energy and were half computing become more akin to those of fertiliser run•o the size of conventional circuits. human thought, says Joseph Bates of ROM the air, the Flint river basin in Managing the probability of errors and Singular Computing, a rm based in Fsouth•western Georgia looks monoto• limiting where they occur can ensure that Newton, Massachusetts. In the messy nous. Appearances, however, deceive. the errors do not cause any problems. The process of brain activity, synapses trans• What seems a Euclidian as well as a geo• result of a mathematical calculation, for mit signals imperfectly between nerve graphical plain is actually a landscape of example, need not always be calculated cells, he notes. Rather than squandering low hills, shallow valleys, stream beds, preciselyan accuracy of two or three resources in a futile attempt to eliminate drainage ditches and river banks. Nor is decimal places is often enough. Dr Palem minor errors, the brain lters them out as the soil the same everywhere. Some is o ers the analogy of a person about to processing moves up to higher mental sandy; some is rich in clay; some is a mix• cross a big room. Rather than wasting time functions. Together with Charles River ture of the two. These details matter if you and energy calculating the shortest path, Associates, a consultancy, Singular is are a farmer, which many residents are. it’s better just to start walking in roughly working on a $700,000 project for the US From the air, too, something else is the right direction. Navy to design an approximate comput• apparent: a strange tendency for the ba• ing video•processing chip to increase the sin’s crops to grow in circular patches. This Perfection is overrated ability of battery•powered drones to track is caused by the way they are watered, for The microprocessor that powers a laptop potential targets. the predominant system employs sprin• typically contains more than two billion The technology behind sloppy micro• kler heads attached to hoses that dangle transistors, but it could run just ne with chips is now ready for widespread use, from wheeled trusses which move in a one•eighth or even more of them produc• says Vivek De, Intel’s head of circuit re• circular pattern around a central tower. ing sloppy results, says Mr Lingamneni. search in Hillsboro, Oregon. But will com• The whole arrangement is portable, and The key is to ensure that sloppy circuitry is panies that exploit sloppiness to boost can thus be transported from eld to eld used only for certain tasks. It is not accept• performance or battery life want to admit in order to water a whole farm. able if one le is attached to an e•mail but it? Buyers might think twice before buying Centre•pivot irrigation, as this system is another le ends up being sent. a device that operates with errors as a known, is reasonably e ective. But it is a Can information that must be pro• matter of course, concedes Hang Chang one•size•ts•all approach to distributing cessed accurately be kept away from the Chieh, a professor at the National Univer• water. Craig Kvien, of the University of faster, sloppier circuits? Mr Lingamneni sity of Singapore. Georgia, thinks he can do better. In 1999 Dr thinks it can. CSEM is developing an error• Researchers have coined a variety of Kvien came up with the idea of varying prone chip for audio•visual processing in euphemisms to describe the technology, the amount of irrigation water applied mobile phones that dispatches di erent such as inexact hardware, probabilistic across a eld, in light of a detailed exami• processing tasks to the appropriate circuit• computing, relaxed correctness and nation of that eld’s characteristics. In ry. The voltage is reduced in parts of the relaxed reliability. In ve years your collaboration with FarmScan AG, an chip that nish calculations faster or with smartphone or computer is unlikely to Australian manufacturer of agricultural greater accuracy than necessary. Other sport a sticker boasting that it contains equipment, he and his colleagues have parts of the chip, where more important chips that sometimes get their sums developed this approach into a technique calculations are made, operate at higher wrong. Even so, such chips may be lurking called variable•rate irrigation (VRI). More voltage and with fewer errors. inside, increasing performance and than 80 farms in Georgia now use it. Farm• Another approach to managing errors, extending battery life.

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