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Sensoring the vertical — Parallax Forums

Sensoring the vertical

MoskogMoskog Posts: 554
edited 2011-11-21 22:12 in Accessories
Anyone here who know about a cheap sensor to detect the vertical (or horizontal) level? I need such a sensor to place on an arm to know if its standing right upwards. Accuracy withing one or two degrees. For easy interfacing with Prop or Bs2.

Comments

  • TumblerTumbler Posts: 323
    edited 2010-11-11 04:30
    You can use the Memsic 2125 accelerometer for it:http://www.parallax.com/Store/Sensors/AccelerationTilt/tabid/172/CategoryID/47/List/0/SortField/0/Level/a/ProductID/93/Default.aspx

    And take a look at this article: http://www.parallax.com/Portals/0/Downloads/docs/prod/compshop/TiltDispCntrl.pdf

    I'm not sure if it detects 1 or 2 degrees
  • MoskogMoskog Posts: 554
    edited 2010-11-11 22:05
    Yes, thanks, I could probably use one or two of those.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-11-11 22:36
    Hmm. Building a deflective wind gage? Plastic toilet tank floats make excellent omnidirectional wind catchers for those. :)

    -Phil
  • MoskogMoskog Posts: 554
    edited 2010-11-12 00:22
    No, Phil, I build those of big dippers from the skies.
    In this case I want to make a sensor to detect the angel of a pallet fork compared to the ground. I have a setup similar to the attached picture, the real problem is to see the fork from behind the stearing wheel and know exactly if the fork is leveled right when picking up a pallet. The front parts of my tractor is hiding the fork when its lowered to the ground, forcing me to hang out of the side door when fine-tuning the fork.
    7172437_520x0.jpg
    520 x 345 - 46K
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-11-12 00:29
    If you're only trying to determine level vs. not level, a couple rolling-ball level sensors at a slight angle to each other (the relative angle depending on your tolerance) might be all you need. These might be more sensitive than a solid-state accelerometer for small deviations from level and easier to interface as a bonus.

    -Phil
  • Ed TEd T Posts: 50
    edited 2010-11-12 06:22
    Do you care about the forks being level or parallel to the ground? If you are on a slope these are obviously not the same thing. Or are your pallets always on ground level to 1-2 degrees?

    - Ed
  • FranklinFranklin Posts: 4,747
    edited 2010-11-12 09:56
    The bucket on my tractor has a rod attached to its top that slides through a ring on the loader arm so that when the bucket is level with the ground a mark is in the ring. You might be able to do something along those lines but I couldn't tell from the picture.
  • kwinnkwinn Posts: 8,697
    edited 2010-11-12 10:24
    It sounds like you will need to measure both the angle of the tractor in order to get the forks parallel to the ground for insertion under the pallet, and the angle of the forks to be sure the load stays put.
  • MoskogMoskog Posts: 554
    edited 2010-11-12 13:20
    @ Ed T: The best thing would be if I could be able adjust the fork both parallell and level to the ground but usually I need the fork parallell.

    @ Franklin: Yes, that would be a very simple solution, but I would like to have the possibilities of adjust it leveled to the ground too, just in case the slope and other, different situations. The picture is not my tractor but something I found on Internet just to clear up things.

    @ kwinn: Yes, I think I need to measure both the tractor and the fork. There is another thing too, I'm not using only the fork but other kinds of tools in front of the tractor. Things like tractor buckets for sand or snow. These are tools that all needs to be adjusted different to get the right angel compared to the ground or to the loader arm.

    My scenario is that I have a box inside the tractor. There are (let's say) three buttons on the box, one for the fork, one for the snow bucket and one for the sand bucket. There is a LED-display that shows the angel of the tool where 0 degrees is level and with - or + depending on the tilt. The microcontroller adjust for whatever tool I use. Maybe I can use two displays to keep control of level to ground or level compared to the tractor.
    So when attaching the fork I push the Fork-button and read the angel, same thing with the other tools.

    Sorry for confusing explanation but I wasn't born with the English language!
  • Ed TEd T Posts: 50
    edited 2010-11-12 14:09
    How about 2 sensors of the type suggested by Tumbler in the second post. One on the fork and one on the tractor (It could even be in the box with the micro if you mount the box appropriately). Have a multiple LED display for both the fork and the tractor versus true level. If you want the pallet fork at true level then just look at the fork LEDs and adjust to the zero LED. To make the fork level with the tractor/ground adjust until the fork LED that is lit is the same as the tractor LED. If there is an offset from the fork sensor for each attachment then have a knob that you select the attachment and that determines on offset added to the fork reading.
  • FranklinFranklin Posts: 4,747
    edited 2010-11-12 16:04
    Maybe I can use two displays to keep control of level to ground or level compared to the tractor.
    Won't the tractor also be on the ground and thus 'level to the ground'? Tumblers two sensor would be the best electronic solution unless you wanted to go ultrasonic.
  • MoskogMoskog Posts: 554
    edited 2010-11-13 00:01
    Franklin wrote: »
    Won't the tractor also be on the ground and thus 'level to the ground'? Tumblers two sensor would be the best electronic solution unless you wanted to go ultrasonic.

    I meant to say one display will show level to the ground (or level compared to the tractor) and one display show level to true ground (water surface).

    @Ed T: Yes, I think I will go for something like that.

    The Tumbler-sensor will probably be the best solution!
  • kelvin jameskelvin james Posts: 531
    edited 2010-11-13 09:35
    Couldn't reading a pot at the fork pivot point be used instead ? I am not sure of that type of structural lift setup, but the forks should always be level to the tractor at a certain known angular position.
  • MoskogMoskog Posts: 554
    edited 2010-11-13 10:02
    kelvin james
    Of course a pot could work, but I'm concerned about the environment that could be quite rough sometimes. It needs to be very good protected as the tractor is used in very different conditions: Like in forresting, snow and rain and others. I would prefer a sensor with no moveable parts protected in a waterproof box.
  • kwinnkwinn Posts: 8,697
    edited 2010-11-13 10:04
    No apologies necessary. Your english is much better than my second language.

    Two accelerometers and a microcontroller can calculate and give you whatever level readings are best for the mounted attachment.

    Another option is to mount a camera on the front with a display in the cab.

    PS - I think you will have to do some filtering and averaging of the accelerometer signals to get good readings.
  • kelvin jameskelvin james Posts: 531
    edited 2010-11-13 16:16
    There are weather-proof pots available, preference is a linear one for your use, no idea on the cost for these. Not as much fun or challenge, compared to trying to sync 2 accelerometers together in a rough enviroment.
  • MoskogMoskog Posts: 554
    edited 2010-11-14 00:40
    kelvin james wrote: »
    Not as much fun or challenge, compared to trying to sync 2 accelerometers together in a rough enviroment.

    Well, that could be a nice challenge too, especially if I should find a way to level to true ground using pots. It could probably be done a mechanical way, by use of gravity and a weight attached to a pot, perhaps.

    A lot of good and very interesting ideas here, thank you so much for all your replies.

    Another thing, a BS2 or Propeller in the old tractor would be an ugly case of overkill, just for controlling levels. I believe I need to come up with more ideas for additional tasks.
  • kwinnkwinn Posts: 8,697
    edited 2010-11-14 07:16
    Moskog wrote: »
    Well, that could be a nice challenge too, especially if I should find a way to level to true ground using pots. It could probably be done a mechanical way, by use of gravity and a weight attached to a pot, perhaps.

    A lot of good and very interesting ideas here, thank you so much for all your replies.

    Another thing, a BS2 or Propeller in the old tractor would be an ugly case of overkill, just for controlling levels. I believe I need to come up with more ideas for additional tasks.

    I would suggest sticking to accelerometers. They have no moving parts to be affected by the vibration, dirt, and moisture being mounted on a tractor entails. As to the BS2 or Prop being overkill, I do not agree. A micro with on chip ADC's may be a better choice but there is enough processing required to filter the signals, calculate the angles, and drive the displays, that using a BS2 or Prop can be justified. Personally, I would start with a protoboard for a project like this.
  • MoskogMoskog Posts: 554
    edited 2010-11-14 13:51
    kwinn wrote: »
    ...Personally, I would start with a protoboard for a project like this...

    I have now ordered two accellerometers from Parallax so that will be the way to go. I have two other projects currently running and also working on modifying a third. But with all the inputs here I think I've got some really good ideas now and I do look forward to start prototyping as soon as I can.
  • graffixgraffix Posts: 389
    edited 2011-01-01 17:11
    keep in mind there are temp probes in the memsic.outside temps varying hot cold will effect your data.sample code is based on roon temp.keep in mind im new,but seemed like a notable comment.
  • MoskogMoskog Posts: 554
    edited 2011-01-02 12:52
    Due to the datasheet the operating temperature range is between 0 and +70C. I will be using the sensor outside with a temperature range from -20 to +25C. The sensor will be placed in an enclosure and there will be no problem making a kind of heater to keep a stabile temperature, in case temperature changings affect the accuracy.
  • ercoerco Posts: 20,255
    edited 2011-11-12 09:14
    I'm resurrecting this year-old thread just 'cuz today's eBay DoD is a tilt measuring device: http://cgi.ebay.com/Digital-Magnetic-Angle-Cube-Level/370390804867?_trksid=p1468660.m2000037
  • Ed TEd T Posts: 50
    edited 2011-11-12 12:01
    Moskog - Did you ever do anything with this? If so I would be interested in how it worked out.

    --Ed
  • MoskogMoskog Posts: 554
    edited 2011-11-13 13:26
    Ed T, oh yes, the project is on its way, I made a prototype based on a Propeller and two memsic accelerometers. I faced a minor problem with reading the values from the remote mounted memsic, but solved the problem with good help from forum members here. (Another thread) I did plan to make a real test on the tractor this weekend but bad weather here forced me to stay inside instead. But the proto is ready to be placed on the tractor and the elevator now and I hope to continue outside as soon as possible. Shame the daylight is about to disappear too, its getting dark outside at 4pm and days will still be shorter for another month or so. I will be back with an update when tests are done!
  • kwinnkwinn Posts: 8,697
    edited 2011-11-21 22:12
    Moskog wrote: »
    ........ Shame the daylight is about to disappear too, its getting dark outside at 4pm and days will still be shorter for another month or so. I will be back with an update when tests are done!

    Ah you southerners. Always complaining about the weather and darkness in winter ; - ) Although I am living in Edmonton Canada now I came from Harstad Norway originally. Now there you have real winter weather and darkness.
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