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#1
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Hello there
We want to control our system using switches, problem is, the the provided MicroSwitches can only be pressed from one direction. (e.g: only when our system goes up, but not down) What switch can be pressed both ways without braking? Sorry if I am unclear, english is not my primary language, and I lack much of the lyngo Yoni Savransky Team 4712 TracBots Last edited by yonisav : 26-01-2015 at 18:12. |
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#2
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Re: What switch can be pressed from both directions?
Can you explain what you are trying to do? There may be a simple solution using the parts you already have. |
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#3
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Re: What switch can be pressed from both directions?
Sure thing
To lift the totes up and down we have a system that goes up and down. To regulate it's hight, we want to create "levels". a level for the height of 0 totes, a level for the height 1 tote and so on. To know what level we are on we want to use a boolean sensor, that is pressed by the moving system. (we tried a sonar but it wasn't robust enough) What I am searching for is that boolean sensor |
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#4
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Re: What switch can be pressed from both directions?
Could you not put limit switches at the various heights to achieve this control?
If switch one is closed ------- you are at level 1 If switch two is closed -------- you are at level 2 etc I am not sure what you mean by a Boolean sensor.... |
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#5
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Re: What switch can be pressed from both directions?
In my mind a boolean sensor = a switch
Unless I am a complete idiot (which I may very well be) no, since they will break when the system comes down (or up, depends how you position them) If you do have a solution in mind, please give me a picture or something, I want to be sure I understand what you are talking about Thank you very much for the help |
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#6
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Re: What switch can be pressed from both directions?
Take a look at this switch
Its a roller plunger limit switch... it would work going both ways with some sort of pin on the moving piece. http://www.mcmaster.com/#7076k26/=vn1q8t Hope this helps.. |
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#7
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Re: What switch can be pressed from both directions?
This seems pretty much like what I need. Thank you
One more question, we have a few of these: http://www.clasohlson.com/medias/sys...3445556254.jpg Can they be used for the same purpose? I found these: http://www.amazon.co.uk/Roller-Plung.../dp/B007Q81BTS online, just to make sure, will it work for us? Last edited by yonisav : 26-01-2015 at 19:04. |
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#8
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Re: What switch can be pressed from both directions?
You could also use a beam-break sensor. It's a small light and a small receiver. In ordinary operation, a beam of light goes from the light source to the receiver. If the beam is interrupted by something (say, a tote), then there is something there.
This sort of thing used to be quite common in FRC for various applications. |
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#9
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Re: What switch can be pressed from both directions?
If you are trying to do this with something much smaller than a tote (like a tab of angle aluminum), you can get an integrated system. Sparkfun also sells the breakout board. For about $4 you can have a sensor that's ready for a PWM-style cable that can plug directly into a DIO port. I just ordered ten of these yesterday, so I had the URL handy:
https://www.sparkfun.com/products/9299 We used one of these (or something very similar) and a plastic disk with holes as an encoder on our first robot for Rebound Rumble. |
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#10
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Re: What switch can be pressed from both directions?
A roller rocker switch would probably also work (such as this). I think there was one in the kit a couple of years ago, because we have a couple laying around.
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#11
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Re: What switch can be pressed from both directions?
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The UK switch would work fine... but don't forget those are from the UK and it might take awhile to get them... plus shipping... 3 weeks left.... There are a number of solutions to this... i agree that photo sensors would work well too... these would be more expensive (the ones we used on our robot were probably $50-$60 a piece ) but you could make them yourself... lots of DIY type photo sensors could work. Another route you could take is to encode the motor that is driving your elevator and choose positions... more programming .... but an elegant solution. Another idea is a string potentiometer like this one from AndyMark http://www.andymark.com/product-p/am-2618.htm Definitely you want a pin or a tab on the elevator that activates any kind of limit switch. pins work nice.. could be something as simple as a bolt that sticks out of the frame. good luck |
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#12
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Re: What switch can be pressed from both directions?
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#13
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Re: What switch can be pressed from both directions?
Of course, with any of the roller or rocker switches, the switch should be beside the load so that as it moves past, it and shoves the roller or rocker aside. Alternately, it could be tucked safely behind the stop so that just the button sticks out. Somehow, you should ensure that your sensor doesn't get smashed when the load hits the stop a little faster than you intended.
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#14
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Re: What switch can be pressed from both directions?
We are probably going to end doing something like this: (sorry for my awful painting skills)
http://oi59.tinypic.com/2rcsi1e.jpg Aside from the placement, which will have to be precise, what other problems may arise? |
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#15
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Re: What switch can be pressed from both directions?
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A potentiometer or an encoder, depending on how your powering your system up and down, is what you would want to use here. You can count the rotations of the motor that powers your system with an encoder and do some math to convert that into distance traveled, and just tell the system to go to X height with a PID loop or something. Something similar can be done with a potentiometer. |
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