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Extend your battery life by keeping your computer OFF

Extend your battery life by keeping your computer OFF

Greener computing, computers that use significantly less power, might be coming soon.  How?

They turn themselves off between every keystroke, mouseclick, or touch.

The Journal of Applied Physics has published a very interesting article this week.  The technology, Magneto-resistive Random Access Memory (MRAM), is over a decade old now.  It uses two plates which can each be assigned a magnetic field direction.  The data is read back by measuring the resistance across the plates, if the reading is low resistance then the fields are aligned.  High resistance means they are opposing.

The size of the cells in in MRAM (each cell can store a bit) and the high current necessary to program them are the limiting factors in this technology, but enter the Spin Transfer Torque methodology.  This concept uses the spin direction of electrons to modify the magnetic properties, drastically shrinking the cell size, which increases the memory density.  This technology still has some development, but it has the advantage of significantly lower power demands.

Conventional DRAM requires a relatively high percentage of a computer’s power demands, it uses a small capacitor to store an electric charge with a transistor to control it.  This means it is constantly drawing current from the main computer power source.  MRAM-STT needs power when modifying a bit, but otherwise can be shut down.  For any given bit in memory, it is likely that it spends more time being unchanged than changed, meaning the majority of time it can be shut down.  The concept of the article is that it would be possible to build a computer that shuts itself down whenever there is a break in usage of a few milliseconds, then turn itself instantly back on.  The power savings would be immense, and could allow computers to be run off alternative energy sources (solar, hand-crank, thermal).

There are quite a few details yet to be worked out.  If you were  to read through the journal article, you would see that there are still limitations in size and speed, but the analysis shows that we are still moving toward the end goal of a more energy efficient computer.  Personally, I’m looking forward to cell phones that can last through the day while actually using them continuously.

 

K. Ando, S. Fujita, J. Ito, S. Yuasa, Y. Suzuki, Y. Nakatani, T. Miyazaki, and H. Yoda. Spin-transfer torque magnetoresistive random-access memory technologies for normally off computingJournal of Applied Physics, 2014 DOI:10.1063/1.4869828

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A little good news for the motion control industry

A little good news for the motion control industry

This brief forecast has an interesting statistic: “the motion control market tends to grow (or decline) about 1.36 times that of machinery production”   (The article).  I’d never really thought about it before, but it makes sense.

Every machine needs the motion control components to make it work.  It also needs repair parts, additional components to integrate the machine with the rest of the factory, and some extra parts that were ordered and then not used in the final design.  These additional components apparently make up somewhere between 0 and 0.36 of the actual components of the machine.

As far as I’m concerned, the forecast for more machine building in the next few years is a very positive sign!

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Nano-meter precision positioning

Nano-meter precision positioning

Positioning something at the sub-micron level has a lot more involved than might be immediately apparent.  Variations in temperature, the room and foundation, even movement around the area can cause variations in equipment that is more than a few nano-meters, and that’s just for one axis of motion.  This makes it amazing that Alio Industries has managed to combine 3 axis of motion in their Hybrid Hexapod and get a repeatability of less than 10 nanometers!  (That’s positioning in all 3 dimensions, most manufacturers only work in 1 or 2).  You can check it out on their website.

So how can you increase the repeatability of your system?

1. Mount it on an extremely stable surface, granite is a popular choice.

2. Temperature control the room.  A few degrees may not seem like much on everyday systems, but the expansion and contraction of all the parts can add up rapidly when nanometers is the goal.

3.  High resolution position feedback, either extremely high line count encoders, lasers, there are some other options out there.  It is vital to know where the system is located as precisely as possible.

4.  The mechanical parts must be extremely high precision, not only in the dimension of travel, but if the travel surface has a wave, or imperfection, it can throw off the positioning in the other two dimensions as well.

 

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