How Wireless Meshing Could Save Energy

An anonymous reader writes "EE Times reports that the future of industrial automation lies in wireless mesh sensor networks. From the article: 'It is the holy grail of the factory floor: hundreds of sensors wirelessly connected, monitoring motors for problems and drastically reducing energy consumption -- all with the precision and rhythm of a philharmonic orchestra.' (Other articles here(1), here(2), and here(3).)"

Comments

Munchkins...?

[nzgeek]

This idea strikes me as an implementation or extension of "Munchkins" described in an ancient (1996) paper by Rohit Khare and Adam Rifkin.

The idea basically describes very small, low-power devices that can route messages between each other until they find the target device (or a valid route to the target device). I have to wonder whether new devices like the iPAQ with GSM, WiFi, and Bluetooth are trending towards this behaviour. It wouldn't take a heck of a lot to turn the iPAQ 6340 into a device that can intelligently route incoming packets over any of its connections.

I'd love to be able to pick up my cellphone, and connect to my PC via a network of industrial sensors built into traffic signals, bus stops or the nearest ATM.

Radio Luxembourg, the great 208 had 1300 Kw on MW

[GuyFawkes]

The station transmitted to all of Europe via the powerful transmitter site in Marnach on 1439 kHz (later 1440 kHz), 208 metres in the medium wave band. The transmitter pumped out 1300 kW and was Europe's most powerful (only hit by a Russian site which had more power). Radio Luxembourg ceased transmissions from the 208 transmitter December 30. 1991 to be available on satellite and short wave only. Unfortunately CLT decided to close the station at the end of 1992 because it made no money out of the programmes. Luxy returned on the great 208 for one night only - the date when the station's final programme was aired - December 30. 1992.

Re:How secure are such setups?

[rcw-home]

What prevents a competor with a wireless broadcast anteanna from parking in range of your factory, and sending false signals telling your machines to idle?

Standardized AES encryption.

BTW, I'm pretty sure that the article had a typo - they probably meant IEEE 802.15.4 (aka Zigbee), not 802.16.4. The Zigbee FAQ has a lot of valuable information about it.

Re:What about SAR?

[ajlitt]

Usually, but for most devices under the 2m wavelength mark (>150MHz or so, which these would probably be), human body absorbption drops quickly.
Of course, this is moot when compared to the EMI that most industrial electrical equipment generates. Hundreds of 3-phase motors, giant transformers, and multi-kilowatt circuits make for a far stronger field at the low end of the spectrum than an army of small sub-watt range transmitters.

energy savings in doubt

[loophard]

Most industrial motors are used to drive steady-state processes, and are always on. Examples, are drive motors used in pulp mills and refineries. I don't see how any amount of mesh network monitoring is going to drastically save electricity for these always-on motors. A small savings might be found by looking for inefficiencies in the way the motor operates (i.e. it needs maintenance). However, I find the claims of 10-20 percent savings by monitoring somewhat questionable.

For discrestionary motors, like tank filling pumps, there could be some savings found by using the mesh network to control the asset during off-peak hours, where often the electricity rates are lower.

security features of the IEEE 802.15.4 spec

[dtmos]

Almost correct. You need AES-128 authentication and message integrity checking, not encryption, but ZigBee has both. Encryption merely makes the message private, but authentication ensures that the source address wasn't spoofed, and integrity checking ensures that it hasn't been corrupted or modified before reaching the recipient.

BTW, the IEEE 802.15.4 spec is available for free download.