Let's Make Robots!

Spurt - Line following Beambot

Line following

Spurt is a brainless line following Beambot. It is based on the Spurt-Mobil from the University of Rostock / Tech. University of Berlin. It is a very cheap robot platform, easy to build.

Parts needed:

  • 2x motors Mabuchi FF180 12V
  • 2x rolling bearings 680
  • 6cm round bar from beech 8mm
  • 2x wood dowels 8mm
  • 1x ballon
  • 2x BC337 NPN transisitors
  • 1x CNY70 photo reflex coupler
  • 1x 1.2kOhm resistor
  • 1x 470Ohm resistor
  • 1x 47Ohm resistor
  • 1x 9V battery
  • 1x  battery clip
  • 20cm wires red/black
  • 1 piece of veroboard
  • 3x 2pin headers/female headers


The scematic is quite simple. The CNY70 refelective sensor is connected to transistor T2. On a white surface the photo transistor is on and T2 drives the left motor, T3 is switched off. On a black surface the photo transistopr is off and T2 is switched off, too. T3 is switched on, driving the right motor. This is how the robot is navigating between the black line and the white area.

All electronic parts has been placed on a littel piece of veroboard. It is easier to replace the electronics for further work.

The chassis is made of wood. An ice cream stick holds all the part, attached with hot glue. The motors have no gears. Lline shafts build from a ballon has been used to drive the wheels (standard inline skater rolling bearings).


Further work:

I think about a double line sensor board, a light follower board and an obstacle avoider beambot. Maybe a CPU based version later.

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

What an awsome little thing! I am truly amazed at it's simplicity, size, and functionality. The rubber band solution is really a clever solution, and an easy way to do gear ratios on the cheap. Good job!

Very minimal and very interesting construction.

I am curious how you keep the rubber band on the wheels...guess it will slip off when the bot turns...

You can prove it by physics that flat belts dont slip of. Years ago the were used very widely: https://secure.wikimedia.org/wikipedia/en/wiki/Belt_%28mechanical%29

Physics tells that flat belts have the tendency to climb to the highest point of the pulley; wikipedia says: "Because flat belts tend to climb towards the higher side of the pulley, pulleys were made with a slightly convex or "crowned" surface (rather than flat) to keep the belts centered." Indeed the bearings are flat, but a belt at the edge would "try to slip back".


 Works bretty good with no brain. Can't get much smaller for home made for sure.

You *can* get it smaller, please look there: http://spurt.pbworks.com/Simpelmobil

Thank you guys. In the beginning I was sceptical about the rubber band solution, but it works pretty well. As long as the motors and the axis were in parallel. OK, the rubber bands don't last long, you have to replace it a lot.

Great little machine this - just goes to show what you can do with very little

Nice little bot,and I like the bearings and rubber band coupling :)  Aren't you using diodes to protect your transistors?

Good point, Korel. I will add some flyback diodes soon.

I'm learning too my friend :)