Jan 9 2012
Bart van Vliet

Review of Arexx Caterpillar

The caterpillar is an excellent robot to start off with in robotics. It has servos and sensors, you can change the hardware and you can program it yourself.

Assembled caterpillar


The package contains many parts which you have to assemble yourself. This consists mostly out of screwing things together, a bit of soldering and connecting cables. The instructions are easy to follow (pay attention to which screws you use though). The soldering was a bit harder, especially the touch sensors have to be soldered exactly. Connecting the cables was a bit of a guessing game, the manual wasn’t very clear about it. The total assembly took about a day.


The included software includes a nice GUI to connect to the robot. You can read out values, use the commandline and upload, start and stop programs. Unfortunately the GUI did not work on my system (ubuntu 11.10), so I used windows. I’m sure though that there are other programs to connect to the robot, since it uses UART.

Caterpillar GUI

The robot comes with some example programs, with source code, so it’s easy to modify and start making your own programs. At first, it is a bit tricky to combine the servo commands in such a way that you get a smooth movement, but later you do this with ease. In the video you can see my own programmed sidewards movement. The biggest problem I had was that the servos are a bit weak. Since the board has some room for extra sensors, you can add some and make it more autonomous. Or you could even completely change the hardware and build a completely different robot (a walking robot for example).


  • ATmega16A processor: 16 MHz, 16 KB flash, 512 B EEPROM
  • Actuators: 8 servos, 4 LEDs, beep speaker
  • Sensors: IR sensor, 3 touch sensors, 2 roll sensors

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