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Help with Limit Switch or Sonar Switch Stop

  1. Jun 24, 2014 #1
    I am looking for some assistance in creating a way to stop a skid steer loader that drives on a confined course if it hits the wall. We currently operate a theme park where children drives skid steers loaders and we have a remote E-stop. the course is enclosed and surrounded by a barrier system. I am looking to see if there is some device that can be mounted in the front of the machine and wrap around the front end that shuts off the machine the minute it makes contact with the barrier system. For example a limit switch, would work but we have a 5' wide front area so we need a way to cover the entire area as the impact can be from various angles. Essentially when contact is made it trips a relay and shuts of the engine like our remote E-stop and prevents barrier damage.

    Would any engineers have some ideas into this creative system or suggestions on a device?

    Thank you
     
  2. jcsd
  3. Jun 24, 2014 #2
    What about looking into a modified http://en.wikipedia.org/wiki/Pet_fence
    Of course the "shock" would instead cut off the motor, I am pretty sure that shocking children would be frowned upon.
    Otherwise you could look into some sort of mechanical switch but the problem with that is if they're triggered its already too late.
    Another option (we used this method for our third year robotics competition) is a IR distance sensor, however there is a lot of variables to deal with, such as multiple sensors interfering with on anther, ambient temperatures affecting the sensor level etc
     
  4. Jun 24, 2014 #3

    berkeman

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    Welcome to the PF.

    Can you post a picture of what these vehicles look like? You can link to a picture on the web using the little painting icon in the Advanced Reply window, or you can upload a picture file from your PC using the Attachment feature.

    Also, you just want to disable the vehicle if it contacts the barrier, as opposed to other vehicles? Are the bumpers different heights on the barrier versus other vehicles?
     
  5. Jun 24, 2014 #4
    thanks for the reply. I just want to disable the vehicle if it hits the barriers. I have attached the image. all of the vehicle and the bumpers are of the same height. I have attached 2 images.
     

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  6. Jun 24, 2014 #5

    berkeman

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    Holy Smokes! You have kids at a theme park driving full-size skid steer front loaders? Yikes! I've never seen anything like that! Where is this place? How old are the kids?
     
  7. Jun 24, 2014 #6
    this is Diggerland USA located in West Berlin, NJ. www.diggerlandusa.com

    its a fascinating concept and we are always refining safety to make it better.
     
  8. Jun 24, 2014 #7

    berkeman

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    Wow, that's crazy! :biggrin:

    So it looks like you've taken the front loader buckets off of the skid steer loaders, and replaced them with a bumper? It's kind of hard to see in the pictures. If so, then you should be able to fit them with a wide bar in front, and shorter 45-degree bars on the sides of the front bumpers. The bars can be spring loaded with several limit-type switches spaced along them, wired so that if any one of the switches close, that activates the kill sequence for the loader. Would that work?

    I gotta send that link to a few of my friends.... :smile:
     
  9. Jun 24, 2014 #8

    dlgoff

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    Holy Crap. :bugeye: Now I've seen everything. I'm wondering what my daughter would have taken up if I had taken her there. :wink:
     
  10. Jun 24, 2014 #9

    dlgoff

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    Agree. [STRIKE]Parallel[/STRIKE] Series these limit switches and use as the stop switch as in this typical motor start-stop switch circuit.

    01295x01.png

    Edit: Sorry. See strikeout.
     
    Last edited: Jun 24, 2014
  11. Jun 24, 2014 #10
    thanks everyone that's the direction I was thinking but wanted to vet the idea to be sure I did not miss another idea such as micro or pressure switch.
     
  12. Jun 24, 2014 #11

    berkeman

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    Probably your biggest challenge will be to make the bumper assemblies mechanically robust. The switches should not bottom out when the bumper bottoms out (use mechanical limiters to tune the travel to be enough to activate the switches, but not to bottom out the switches...).
     
  13. Jun 24, 2014 #12

    Baluncore

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    Have you considered a “software fence” solution using differential GPS?

    Use one local GPS base station broadcasting to all units. Each unit has a GPS receiver and a map in their system, notebook or pad. They are progressively speed limited as they approach the soft fence, they stop as they cross it. That quickly teaches the riders / drivers to keep clear of the fence.

    I find operating JCB equipment a great way of productively releasing stress.
     
  14. Jun 24, 2014 #13

    AlephZero

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    I would suggest you get in touch with JCB headquarters. If they still have the ethos of the company founder Joe Bamford, they will probably give you some professional help.

    Joe was a larger than life character with a very "hands on" attitude to running the company. At one time, every new employee (literally everybody, not just the engineers) spent the whole of their first week learning to drive the products. Joe's view was that if that didn't turn you into a "JCB person", nothing would. And it worked. In the 1970s, productivity at JCB was about 7 times the UK average for manufacturing industry.

    He certainly believed in putting on a show - he bought one of the first LearJets off the production line to ferry prospective customers from around the world to sales presentations, and drove them from the airport to the company HQ in a stretch limo with the same number of seats as the jet :smile:

    But don't let the kids try stunts like these ....
    https://www.youtube.com/watch?v=cD8EqthDi1o
     
    Last edited: Jun 24, 2014
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