At the beginning of this assignment I was really attracted to the idea of creating something that could move around without using any kind of wheels, to be able to create different motion sequences and to be pretty cute and funny to watch at the same time. That’s when RoboCat was born!
My very early sketches were something like this:
Using sensors for interaction
The initial concept was simple, 2 front and rear mini servos to power four legs, and make it move. At early stages, I also considered using a motion sensor, that way RoboCat would only move when movement was detected by an IR Pyroelectric Infrared PIR Motion Sensor:
After a few failed attempts I realized the motion sensor would take too much voltage with the 2 mini servos, because of this, both servos wouldn’t function properly, and there was a small short circuit with the wiring later on.
I reached the point of sacrificing the motion sensor to make the motion work properly. Later on, I also noticed that when RobotCat first prototype was built together, the movement was making the readings quite unstable as well.
I replaced it with a flex sensor, hoping that it could trigger different motion sequences and also turn on 2 RGB leds, when it was bended.
Prototype testing process
The first tests were a bit successful, but readings were quite imprecise. The following step, was to design a body that would make as RobotCat’s body and head. The unfinished prototype looked like this:
Sadly after adding RobotCat’s styrofoam head and placing the 2 RGB leds circuit, a spring and the flexsensor underneath, readings became more erratic and sometimes didn’t work at all. Constant motion due to imprecise readings caused the servo motors to overheat and sadly the back motor burned after a little while of constant motion. 🙁
The Final Product
Finally, I switched to our dear old friend, the ultrasonic sensor, very close distance would trigger motion and turn on RGB leds.
Robocat’s default motion sequence was a bit slow so that servo motors wouldn’t overhead and he would happily dance if you reached close to his face and his eyes would turn on. Different distances would trigger different motion sequences, or levels of excitement for RoboCat when someone was getting close to him.
Robocat’s code is available here: https://github.com/mcgm87/RoboCatCC.git