My first simple robot

Schematic for the would be robot, containing branching decisions

This project was the first that required us to build a machine with a purpose. It did not have to be super complex, however it needed to look good while its secondary objective is to perform a movement. My knowledge at the time was limited to motors, so I went with the idea of a rotating robot, my choice of material was 3D printed part because it allowed me to produce the exact shapes I want.


How it should be set up

To make it more interesting, I wanted this thing to move its upper body on one polarity while its head would be rotating randomly while moving in an opposite direction. I also wanted to give him LED light eyes so that whenever he rotates, the color changes from red to green. Thinking back that was more than 2 features and I bit more than I could chew as it was the first time I had to work without a breadboard.

To achieve both global and local rotation, I needed a base for the global rotation that would connect with the base for the local one. In short I needed to move the torso and head independently. I figured I would need some sort of spine system. Thus I devised this.

The 3D printer would only print out maximum of 4 inch parts. It would have had too little space to house all the wirings and electronics, so I chunked the body parts including the head, into 2 halves and glued them together afterward.

However I made a mistake submitting the exact same half for the head. I had to use a power drill to create a 2nd hole for the right eye afterward.

There's another eye at the back

During 3D fabrication I made sure the thickness of each part (1mm) won't clip over each others. It was even harder when you have to consider how much it will expand after you add thickness to the parts, so that they wont exceed 4 inch in dimensions. Some calculations were required. I also needed to calculate so that the parts would have a tight fit when you install wooden wheel and motor blades inside, so they won't flop out.

Preparing the global and local rotation modules
Attaching the body, wire goes from the bottom motor through a small hole
Wire grafting to bring the power lines of the two motors to the main 5volt line
The 9 volt battery
Which I replaced with the 12 volt

The picture below shows the spine being glued and ready to accept the head motor. 

While there was plenty of space to house the wiring, there wasn't enough space for them to move around and due to that, they would always get entangled and choke the motor. The solder would fall apart due to the motor ripping it off, so this part was an exercise of futility.

I planned to have 2 eyes for the robot, however the 2nd eye would not light up when I run electricity through it. Later on I learned that there wasn't enough amperage to support both LED, as the 9 volt battery was being used to support the two motors. Also with the amount of wires going on in the above image, I had to scrap one of the eye for the sake of having enough space to house the other wires from the motors.

I attached a switch for testing, the hole at the back turned out to be quite useful
It is finished

Final product

Due to the amount of wires coiling inside, the glue that was suppose to hold the local and global motors together kept getting broken off. The 12 volt battery was also so heavy that it would fall over and take the wiring with it. So I had to keep it suspended in the air with my hand.

On a brighter note, it was working as intended. The eye lights up green when it's moving and red when its stopping. The global motor was turning fine and although you can't see it, the local / head motor was also turning, the evidence is that it would get caught in the wire and create these "hiccups" movements. This project served as a foundation for my later robotic project, where the issues with power source and wiring were then resolved.

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