Touch

Making a Bump Switch Sensor ¶ 

Article originally seeded with a piece by Matt Mets

One of the simplest kinds of sensors you can make is a bump switch, which detects when it bumps into something. Normally, these are placed on the front of a robot, which is then programmed to back up and change direction when the switches hit something. You can purchase a tactile switch with a lever arm mounted on it that is designed to do this, or build your own using a variety of materials. The switch must consist of two metal contacts that are mounted to levers in such a way that they are normally not connected, but do come in contact when the lever hits something. The microcontroller is then able to sense the collision, by monitoring whether the two contacts are shorted to each other. Here are some examples of homemade bump switches:

The spring bump sensor by Instructables user leevonk uses the stiff spring from a mechanical pencil and a piece of wire to make a durable bump sensor.

Let's Make Robots user isotope built this combination bump switch/cavity detector using some scavenged bits of plastic and metal springs.

Oomlout built a bump sensor using some pieces of twisted wire to make a large bump sensor for the front of their SERB robot.

Harold Ilano's tiny Mercury robot uses the barrel jacks from power supply connectors, along with some stiff wire, to make some robust looking bump switches.

Have a favorite material or technique you use to build bump sensors? We'd love to hear about them. Please add them to this roundup.