elisabettamotta-blog

[elisabettamotta-blog]

Smartphone controlled drawing robot

The first inspiration for my project came from this drawing robot http://www.instructables.com/id/Arduino-Drawing-Robot/ but, because I wanted to make more of a controllable toy rather than a self drawing one, I have also looked into robot cars like this http://www.instructables.com/id/Smartphone-Controlled-Arduino-Rover/

For the very first prototype I have just connected the motors to the Arduino board using an H-Bridge

For learning how to use the H-Bridge properly I have looked at these tutorials:

http://blog.whatgeek.com.pt/2015/03/arduino-l293d-dc-motors-control/

https://itp.nyu.edu/physcomp/labs/motors-and-transistors/dc-motor-control-using-an-h-bridge/

http://jduelfer.github.io/arduino/2016/10/26/arduino-h-bridge.html

For the first prototype I have also written the code to control the direction using a keyboard input referring to this tutorial

http://www.instructables.com/id/Controlling-Servo-motor-using-Keyboard-input/

When everything was responding the the wanted input I have started to build the second prototype with wheels and a chassis

When I have assembled it I had misplaced a wire so, rather than closing the circuit, I was connecting the GND to the + of the battery, which helped me melting the battery holder.

When I figured out what was going wrong I have also realised I could not control the speed of the motors because I was not using the right pins and I was also using the digitalWrite() function.

Looking at this tutorial https://hardwarefun.com/tutorials/controlling-speed-of-dc-motors-using-arduino I have learnt how to use analogWrite() properly, which helped me making the robot going as slow as I wanted for drawing purposes.

After fixing the problems I have started looking into how to use the bluetooth module and pairing it to my iPhone. There are many apps out there that already have mapped joysticks, I have used BLE Joystick for this purpose and it was fairly easy to write the code for it. 

I have created functions for the robot to move forward(), backwards(), left() and right(); in each function I enable the motors and set the speed, then I would call them depending on which message is received from the bluetooth module according to the mapping shown in the app settings.

Unfortunately pairing the bluetooth with an iPhone was not so easy and, after trying with three different Apple devices I thought my bluetooth module was faulty. 

Luckily the next day I had the chance to try to pair it with an Android phone which worked perfectly using the Arduino BT Joystick app.

After I have seen everything was working I have started drawing the schematics for my circuit and soldering it onto a strip-board.

Having to work with an Andoid phone meant that I could not test my soldered circuit straight away so, in the meantime, I have strarted designing a new chassis for the robot using tinkerCad and I have laser cut a cardboard version to check if all the screw holes were in the right places.

After the cardboard I have cut a plywood version adding four small supports to glue the top on and I have also tried which pen would have worked best for the robot. 

I wanted to use different colour pens during the presentation but I could onlu use a black indelible marker as I had to sellotape the paper together to make the surface bigger.

I enjoyed working on this project especially because I had the chance to create prototypes using a laser cutter. It was also fun to make the robot draw and it would be really interesting to do so on a much larger scale.

[elisabettamotta-blog]

Yes, I do always want to make toys...

PHYSICAL COMPUTING PROJECT IDEA

The idea is to make a remote controlled drawing robot on two wheels with Arduino and control it with an iPhone via Bluetooth.

I have taken inspiration from these two projects:

http://www.instructables.com/id/Arduino-Drawing-Robot/

https://www.youtube.com/watch?v=kewza7RyKMQ

The first one is a drawing robot that follows pre-coded instructions to draw shapes, the second one is a smartphone controlled 4WD robot.

I think the drawing robot looks much cooler but, because I think of this as a toy, I like the idea of allowing people to draw what they like without the need of any coding experience but only controlling the robot with something they are already familiar with.

PARTS:

- Arduino UNO

- 2WD Chassis Kit

- Bluetooth Module HC-06

- H-Bridge

- Male to male jumper wires

- Battery pack or 9v battery

- A coloured Pen!

DESIGN:

I would like to use recycling materials for the structure of my robot, so that people could build their own version without having to use expensive machinery. (This does not exclude myself using a laser cutter, I just want to make sure everybody can create something similar with scissors!)