Measuring a Motor

Yeah it should be more foolproof than that. We had someone killed recently here because in home elevators didn't have to meet the safety standards of commercial units. Elevator changed floors while a child was caught in the door.

The motor current, AC or DC, would increase wihen an obstruction imposed a higher load on the motor. Some garage door openers use a current sensing scheme to shut down the motor in the case of an obstruction.

A lot depends on how the stacks are arranged mechanically also. One stack might press against another and move both, encounter a third and move three, and so on . . . hard to make that system absolutely foolproof since by the time several stacks are moving soft body parts might not change the current enough to sense.

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----

----= East and West-Coast Server Farms - Total Privacy via Encryption =----

An increasing load on the motor will cause an increase in current, which can be detected.

The 'crushing' must have already started for the load to have increased. It must also have increased beyond normal operating parameters. Perhaps for a bunch of heavy stacks the extra power required to crush, say, a human skull may be a no more than is required when one of the wheels rides over an imperfection in the tracks. If you wait for an abnormal increase in load it may already be too late. Such a system might have saved that footstool if installed as a failsafe; without knowing the design parameters it's impossible to say. I'd be far from confident such a system would detect squishing something as soft as a person when shoving several tons of books around.

Tim

Am I oversimplifying this, or would it be better to have some sort of spring-loaded pressure sensor along the entire edge?

That's horrible, about that kid that got mashed in the elevator, btw. When you say 'here', where is 'here'?

-phaeton

I'm with you there - a spring loaded switch in the base of the unit might make it 99% safe.

Here is North Carolina - the state that rolls over for industry and the federal government. The corrupt nanny state to end nanny states - the armpit of corrupt government. (well somewhere between Mexico and Puerto Rico anyhow).

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----

----= East and West-Coast Server Farms - Total Privacy via Encryption =----

yes, Current transformers wired into a sensing board can be made to shift the motor in reverse direction or shut it off.

years ago i knew some one that programmed precision camera's that could see images and detect what was there and what shouldn't be there. this system could act up on to spec. these same systems are also used in car manufactures on the assembly line to line up your frame, body parts, front end etc. just by using video viewing and lots of software code to evaluate a solution that normally involved controlling machinery.. i my self implemented this technique for a capacitor company to operate a robotics arm that used multiple mini cams to guide the arm in the operation of picking up the mini sheets of mica via a mini vacuums suction tube, inspect the sheet for zoomed defects, pass it over to another area where another robotics process also using cams would stack the mica to make mica chip capacitors.! very small ones at that. the operators will simply slice the mica and dump it in the little hopper holding area... machine parts were color coded to make it more reliable and less software intense!.. software was done in Delphi, a multiple cam card etc...

The popular US elevators will cut an arm off if the door sensor fails and it's early in the morning (cold oil). I'm much more cautious about sticking a hand in one now.

See

Ew.

They moved independently. It's kind of interesting to see-- first one starts moving, then the next, and the next, with a few inches between them. But even one at a time, they're pretty big.

While there's a thousand ways to skin a cat, I tend to prefer the simplest, most elegant methods.

That's really too bad about NC. I've never been to the Carolinas, but in pictures and legend they sure seem to be otherwise very beautiful and agreeable.

-phaeton

Yeah the land is beautiful alright . . . Too many hog farms, lots of polluted rivers. Some of the rivers I used to sail in, I wouldn't expose unprotected skin to now.

Typical Carolina response to a environmental issue (this is really happening) A rare woodpecker calls NC home. Its range is severely limited and so the EPA wants to curtail more building until the impact of the development is known - NC solution? All the developers are cutting down trees before they might be affected by the EPA - and that is perfectly legal.

Hog farm's open cesspit (spun as a "lagoon") is polluting a local waterway - it just overflows whenever it rains. The local paper is castigating the EPA suggesting that a small family farm is being unjustly burdened. Well that family farm has some 20,000 hogs and produces more waste then the city the paper is located in. I can bicycle past the place (~15 miles) and my lymph glands swell up - they spray the mixture over fields where they also graze cattle - some of the effluent is airborne - a mixture of hog waste with lots of antibiotics - same thing they complain about - overusing antibiotics makes disease resistant strains of bacteria. They give the hogs Erythromycin as a prophylaxis to prevent an outbreak of diseases in the cramped hog houses - raised like chickens are today.

Real estate agent sits on the county commision - real estate agent votes on land he is selling to the commision so they can build a school. No eyebrows raised there.

Governor buys a lot in a ICW development and pays 100 K less then the two identical lots to either side of his. Developer just considers it good business and a selling point - the gov lives here.

Probably no different than a lot of places these days.

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----

----= East and West-Coast Server Farms - Total Privacy via Encryption =----