View Full Version : Contact sensor info. and tutorials needed

12-27-2005, 10:59 PM
Hi I am needing materials and info. about kinds of contact sensors such as bumpers for my project.

So I would appreciate if you could help me with info. and tutorials about this specific topics. <I did search on internet but found nothing readable>

Thank you very much.

12-27-2005, 11:31 PM
why u goin for contact sensors????
i mean u wanted to avoid obstacles,, right???
anyway, u can go ahead with micro switches, they ll get closed with application of very small pressure and ll inform u tat u have touchd something..
or u can have touch sensors made by using the darlington transistor configuration.

12-28-2005, 03:16 AM
If you are touching the objects with a bit of pressure then the easiet thing would be using Micro Switches, they come in various forms. The one which is used in printers for sensing Paper is the most sensitive one I have come across. So just rip two three printers and take out the sensors.

12-28-2005, 07:03 AM
Hmm just want to make it clearer. I go for contact sensors because the robot needs to follow the obstacle's contour and this kind of sensor provides better accuracy than proximity sensor if I am not wrong.

Could you tell me more about microSwitches. I searched on the Internet and saw many types (sealed, unsealed, blah blah...) and dun know which is suitable for such application.

To devpriya: thank you for your idea man but it would cost me ton of money to buy printers and then rip them for the switches :D :D. Even obsolete ones are not cheap right? :P :P

12-28-2005, 12:51 PM
hey chill man...
dev nevr askd u to buy new printers and rip them...
go to the local junk mkt and get as many junk 'useless' printers as u can.
rip them off and take out wat ever is needed.

and as far as micro switches goes by, these r mechanical switches which gets activated with application of very less pressure.
go to the local mkt and ask for them, they ll give u many kinds of micro switches.
but even then, if u r touching the obstacles, u r not doing obstacle avoiding and there is no question of grid mapping using dem{tats wat u wantd before}.

12-28-2005, 01:38 PM
I didnt ask you to rip new printers buddy.....I hope you are also an engineering student.....so just go into your comp. sci. lab and ask the attender regarding junk . He will provide you with lots of non-working printers, floppy drives etc.

I have made my micromouse with the stepper motors which I have taken out from a 5.4" floppy drive , which I got from my college's junk. So who asked you to buy them, just look nearby and you will get them for free. Computer junk is mostly useless for people but its very very useful for us.

12-28-2005, 02:33 PM
You can get microswitches in local electronic shops. I have lots of them. They have 3 connectors. One connector is common, other is normally open connection i.e. the circuit is closed when switch is pressed. other connector is normally closed i.e. the circuit is closed when the switch is depressed(released) . You can use them in either of the mode depending on ur application. They may costs Rs.10-20 . I don't remember properly.


12-28-2005, 05:15 PM
Thank you, buddies!!

Sorry devpriya :) I just want to add some joke, not serious. I will try to look for those switches in the junk devices. You helped me a lot. :D

And for the question of Addy, actually following the object's outline is one of the task in region coverage. Do u guys still remember the IN and OUT critical points from paper of Mr. Choset? I think I can find them using this kind of sensor. Anyway, if you have any comment on this please please let me know then. I'm always greatful to hear from you. :)

About the microswitches, thank you subot_robot for your info. but I would appreciate if you guys could tell me more about this :)

12-28-2005, 08:23 PM
u don need any more info about micro switches dude...

jus get hold of one of dem and u ll understand everything.
they r self explanatory.

12-28-2005, 09:52 PM

If you dont want to smash up a bunch of poor, helpless printers :lol: , you can break open an old mouse. They have reasonably sensitive microswitches inside. The only problem is that the button for pressing is a bit small so attaching a bumper to it is a bit tricky but not impossible (I managed with a spring from an old pen, some tape, some glue and a little piece cut out from an old handkerchief). Another good way to make a sensitive switch is to straighten out a paper clip and put inside a longish ballpen spring. Make the spring and the paper clip the two terminals and you get an insect antenna like switch.

I dont know about the microswitches they sell in shops, the small square ones with the round buttons, they all seem a bit to difficult to press. I tried experimenting with them, but my bot used to run straight into a wall without triggering them.