Ar(m)duino

Inspiration

This new year's, we decided to try something very new. We decided to add a mechanical component to our usually electrical and software focused projects.

What it does

Ar(m)duino is a robot arm with a hook at it's tip, which can be used to pick up things. It uses a joystick and a potentiometer for control and 3 servo motors for movement.

How I built it

A rectangular base was first constructed with the cardboard to house the servo motor controlling the shoulder movement of the arm. Another servo motor was attached to the end of the shoulder piece to control the rotation of the hook. The last servo motor is attached near the previous one, which controls the "hooking" movement of the hook.

Since three SG90 servo motors draw almost 800mA, it is not possible for one Arduino to power all three, since the 5v line of the Arduino provides a maximum of 500mA. Hence, we had to use two Arduinos, one controlling the shoulder and hook rotation with a joystick, and the other controlling the hooking movement with a potentiometer.

The entire setup

Challenges I ran into

Powering all servos was the major challenge, we initially though of using two 9V batteries in parallel and using a voltage divider circuit to bring everything down to 5v logic. In the end we decided to use two Arduinos, since we had the parts needed, and the circuit would become too complex and waste energy as well.
Our team was based in different cities. And building a robot in an online environment meant that only one of us could actually build it. And we had to conduct electrical testing over Skype, which was not easy, as our code required constant iterations.

Accomplishments that I'm proud of

Being able to build a working robot online. We're especially proud of this.
Incorporating a mechanical design instead of a purely electrical/software project.

What I learned

We learnt alot about the mechanical design of arm based robots, and how to make sure it's movement doesn't topple the entire robot.
We learnt about strategies for powering circuits that require more current than the Arduino can provide.