We all have need of that last line of defense when the SONAR glitches, the IRPD doesn’t and our bot is on a collision course with a table leg. That last defense against re-kitting is a bumper. I have made a few from microswitches, miniswitches and other things – usually they work, sometimes they need too much force to work and “ugh” collision. This example is another type of sensor that doesn’t use a switch, its parts are super cheap and it works just great. Its a “whisker” bumper.
Let me show you some pictures and describe what is going on, a picture is worth a thousand words in this kind of game.
This is the top of the PC board with mounting holes drilled. Note centering of the two Berg headers and the whiskers so they go directly between the leads. This side of the board is NON conductive! It is about 1.5cm between the point where the wire goes through the board and the Berg headers. I pulled the plastic separator off to install the whiskers then put is back on loosely, mostly for looks I guess.
I have carved out two places for the contacts and then shorted the two of them together with a wire. You could have two different inputs here if that is needed. The wires each have a ‘Z’ bend in them where they are soldered to the large conductive surface, this gives better support than just running the wires through.
The top image shows the whole thing with all the bends and wires. If you have trouble soldering the whiskers to the board, gouge out a smaller area in the board to solder them to and buff the wires with some sand paper so the solder will stick well.
It doesn’t take much to make these and all of the parts are really cheap. They look cool, work reliably and are cheap – What more could you want?
Copyright 2006 [url=http://users.frii.com/dlc/robotics/botlinks.htm]DLC[/url]Parts:Small piece of single sided un-etched PC board (I use 3.5cm X 2cm)
Two lengths of 1mm piano wire bent into your appropriate shape (hopefully both the same!)
Two 2-pin “Berg” headers
A little bit of wire