OT: Crane Position Measurement

Hello forum,

I'm looking for options to measure the absolute position of a crane over a distance of approx. 100M and at an operating temperature of -27C (-16.6F).

The system being replaced is an encoder with a fixed reader on the crane and an encoded track fixed to the static parts.

I like the look of the Stegmann KH53 system but I haven't had a quote yet! Pepperal & Fuchs do a laser system that works down to -30C but I hear from another site that it suffers from linearity issues (???).

Can anyone offer any opinions (good or bad) on other alternative products that might fit the application?

Thanks in advance,

Nick

I don't have an opinion, but look at BEI encoders. http://www.beiied.com/encoders_harsh_environments.html

At the bottom of the linked page is a statement about additional testing for extreme temperatures.

They also offer a wireless interface.

Check this one:

Leuze AMS200

With lens heating it could go to -30C

I agree with the laser optical device. I have experience using a similar product from Sick. Worked great, and nothing mechanical to couple. Just mount the laser on the moveable crane and point it at a reflector. Extremely accurate and reliable.

Thanks for the responses. I'm now waiting for some quotes.

Nick

What about a radar level transmitter That should work. Mount the transmitter at one end or travel aimed at a large flat part of the crane. If you need something more accurate you might be able to use a cable type magneto-restrictive transmitter with the cable passong through a magnet fixed to the crane.
Roy

If your crane is not prone to skidding or spinning the drive wheel, use a pair of prox switches set in quadrature detecting the teeth on the drive wheel or a flag on the drive shaft, depending on the accuracy you need. Set a photoswitch on a structure to establish a zero position. use a plc or programable limit switch to track the position and integrate into your control.

Depending on the tolerance and the span you may have to track both sides as a crane can crab (one side skewing past the other.

If power failures ar a problem then a UPS on the tracker may be required.

Well I know it sounds like I'm covering all bases on the flip side... but now that you mention it.. the overhead bridge crane we automated 8 years ago had two Sick laser position sensors, one on each side. The crane spanned about 50 feet. Both Sick lasers were on Profibus.

The bottom line for the application is the accuracy and dependability you need, where you spend the money to get what you require.

Thanks for all the ideas.

The crane works one aisle of a cold storage warehouse and doesn't suffer from skew but the drive wheel does slip on the rail. The current system is a Stahtronic WCS2 system which works well but the encoding rail is easily damaged which is why a laser system is being considdered.

I have found some devices that will work down to -30 and I'm waiting for some quotes.

Nick

TR LE200 Lasers... currently in use in MANY cold storage applications... here is a link to the general spec sheets... down to -30 with Heat Option.


http://www.trelectronic.com/index.php?fuseaction=home.products&prod_ID=51

And... you can usually get a quote within HOURS!

Many interfaces available... including... EtherNet/IP!