RobotRemix #5 - Catfish
by Anton Vanhoucke
This Robot Remix is a combination of the
LEGO MINDSTORMS Set 31313 & LEGO
Technik 42076. The inspiration for the catfish
comes from the amazing fishes of Professor Ikuo
The Design Phase :
I began with a drawing. Then, I made crude prototypes to test a lot of different mechanisms and
weight distributions quickly. I also invested a lot of time in a propulsion system that was only
powered by the tail. That worked, but the movement was unrealistic. So, I powered the front wheels
in the end. I also wrote 10 different programs until I was happy. I think I took the fish completely
apart about 20 times during the desing process.
How it Works :
I'm especially proud of the movement. Using only 3 motors, I was able to animate one mouth, two fins, forward movement, and 3 tail segments. I strived to come really close to true fish behaviour in terms of size an frequency of movements.
Programming Complexity :
I spent about 30 - 40 hours programming the fish. It's hard to synchronize all movements. It is
therefore hard to transition smoothly from one movement (eg. standing still) to another (eg. a slight
left turn). All possible transitions have been made because of the fact that the button is remote
There are 620 parts in the 31313 set and 1020 in the 42076 box. The fish has 530 parts. I built a
fishing rod with the leftovers, but you can't catch the fish with it!
If you want to make one too :
Build instructions an code can be downloaded here