Postion sensor
in [DSP]
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From: mrniles on 10 May 2010 11:34 Hello, I'm searching for a static position sensor. I read half the internet but I can't find the right component, or I don't use the proper words in google. I am looking for an small (smt) component that knows in what position it is in. Face up, face down....etc in 3-axis,..something like to know which side of a dice is up. Does a acclerometer do the trick or do I need some kind of gyrosensor?
From: Tim Wescott on 10 May 2010 11:42 mrniles wrote: > Hello, > > I'm searching for a static position sensor. > I read half the internet but I can't find the right component, or I don't > use the proper words in google. > > I am looking for an small (smt) component that knows in what position it is > in. Face up, face down....etc in 3-axis,..something like to know which side > of a dice is up. > > Does a acclerometer do the trick or do I need some kind of gyrosensor? I am an engineer. Therefore I must answer "That depends": If you only care about position when the thing isn't moving (like your "which side of the die is up") then you need a 3-axis accelerometer. Thanks to airbags they're pretty cheap if you're not looking for much accuracy. If you want this to work in orbit you're up a creek without a paddle. If you want to know which way is up in a moving vehicle, and you mean "down" as in "toward the ground", not "where things go when I drop them", and the vehicle is going to be moving violently, and you need fair accuracy -- then you need more. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
From: Rune Allnor on 10 May 2010 12:33 On 10 Mai, 17:34, "mrniles" <mrniles2(a)n_o_s_p_a_m.hotmail.com> wrote: > Hello, > > I'm searching for a static position sensor. > I read half the internet but I can't find the right component, or I don't > use the proper words in google. > > I am looking for an small (smt) component that knows in what position it is > in. Face up, face down....etc in 3-axis,..something like to know which side > of a dice is up. > > Does a acclerometer do the trick or do I need some kind of gyrosensor? Sounds like you want an orientation sensor. Could a mercury switch do the trick? Or something that behaves like the old-school mercury switches? Tilt the thing too far from some known reference vertical axis, and the connection breaks. Rune
From: Frnak McKenney on 11 May 2010 10:08 On Mon, 10 May 2010 10:34:46 -0500, mrniles <mrniles2(a)n_o_s_p_a_m.hotmail.com> wrote: > Hello, > > I'm searching for a static position sensor. > I read half the internet but I can't find the right component, or I don't > use the proper words in google. > > I am looking for an small (smt) component that knows in what position it is > in. Face up, face down....etc in 3-axis,..something like to know which side > of a dice is up. > > Does a acclerometer do the trick or do I need some kind of gyrosensor? If all you need is a static (debounced) determination of which face is up, you should be able to get by with one or more of these: Sharp GP1S36 Phototransistor Output, Transmissive Photointerruptor with Tilt Direction (4-direction) Detecting (Sharp used to sell a similar item that consisted of a ball bearing rolling around inside a box, making contact as the box's orientation changed.) You can pick up a data sheet via Digi-Key (www.digikey.com), but they don't stock the item and they don't offer a price (bad signs). Newark (www.newark.com) lists several items under Sensors&Transducers --> Tilt --> Mercury, but most are in the $8-40 range for simple contact closures, the kid you'd see inside an old Honeywell home furnace thermostat. The sole exception here, a $2 "ASSEMTECH CW1300-1", provides no datasheet; at that price I'd expect a ball bearing in a shaped channel with wire contacts. <grin!> Or you could buy some inexpensive photointerruptors and... er, "roll your own". <grin!> Frank McKenney -- When we are planning for posterity, we ought to remember that virtue is not heriditary. -- Thomas Paine, The Liberty Tree, July 1775 -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut mined spring dawt cahm (y'all)
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