Cheap, Durable, Very Effective Robot Bump Sensor





Introduction: Cheap, Durable, Very Effective Robot Bump Sensor


How to make a very durable and reliable bump sensor for your robot.

This thing was on a robot of mine ( for several hours and the robot drove around a small pen. The sensors worked flawlessly the whole time, detected every bump and never got bent out of shape.

Step 1: Do It

Make a bump sensor:

buy some papermate mechanical pencils (as in picture #1)
snap the tip off of one.
yank out the spring (picture #2)
Solder an insulated electrical wire to one end.

get some pipette tips (this is what I used but any number of things could be used) as in picture #3

Get a thin (should fit inside the spring) stiff metal rod. I used a thin metal rod from a broken umbrella I found on the street. Solder an insulated electrical wire to one end (picture #4).

Stick the nonsoldered rod end through the pipette so that about half an inch protrudes (picture #5)

Stick the pipette/rod into the spring and bend the metal rod so that its tip touches the spring around it, and glue the pipette/rod base the the base of the spring (picture #6).

Connect the sensor to your microcomputer as seen in the diagram (last picture). The arrow symbol is the bump sensor (a switch).

You're done.

NOTE: this is a 'normally closed' bump sensor, so your microcontroller program should be waiting for a 0 (logic low) on its IO pin to signify a bump.



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    I think a push button switch will be more reliable and essentially do the same thing.

    2 replies

    I wanted flexible bump sensors to reduce collision force. If you have use a flexible whisker as a lever with a push button switch behind it (the configuration I'm guessing you're alluding to) the problem is that depending on where the whisker is touched it can actually bend _away_ from the switch behind it instead of pushing the switch. That's why I wanted the 'switch' to be essentially embedded within the whisker so that it wouldn't care which way it was flexed.

    If you're talking about just using a push button behind a non-flexible lever, you're right that can actually work pretty well, but it increases the collision force required for the sensor to actuate.

    Yes, I was talking about a non-flexible lever and behind it be the push button switch and your right, it will increase the collision force.

    I think a more reliable one can be made if you used a spring, with one of its ends attached to the surface of the bot and making an angle of say 45 degrees, and behind it a plate or wire, this will decrease the chances of the spring getting stuck in place without any significant rise in collision force.


    Now show us how to install the bump sensor into your robot manatee.

    2 replies

    that's no manatee that thar be a hippopotamus

    WOW. How did I manage that little act of stupidity?

    pure genius

    Why not use a momentary push button switch?

    could you please make a few more steps so its a little more under standuble but i get the basic idea. cool

    2 replies

    I added a diagram

    The diagram does help, but I think it would be a little more coherent if you divided the the different stages of building into different pages.

    isnt the intro picture from the new bbc inbetween program thingys.

    1 reply

    I dunno, I just did a google image search for 'bump'

    pretty nifty --- does the spring ever rest on metal rod; so when it bumps, it is always in contact (so it never actually breaks the circuit)?

    1 reply

    yeah, sometimes the spring can get a little bent and remain 'on' the rod longer, but the robot just keeps driving forward until the spring has bent enough to lose contact with the rod. So the robot might drive forward a little longer but it will still eventually detect the wall and back off.