Littlebots: Simple 3D Printed Android Arduino Robots

LittleBots were created to be a simple introduction to robotics. It shows all the necessary components of robotics, sensing, decision-making, and articulation all in a nice, simple to assemble package.

The LittleBot is fully 3D printed, which allows it to be assembled with only 3 screws (7 if you are being over-zealous). It is also controlled by and Arduino Nano, to take advantage of the global community around that. The LittleBot has several modes normally, including wander, remote-control (with android app), line follow, and wall follow. Code for all of these are available on the downloads page of the LittleBots website. All of the 3D printing files for the LittleBot are available on Thingiverse and compatible parts can be purchased from the LittleBots website. The Arduino Code is on the LittleBots download page.

LittleBots .STL 3D Printing Files

• 2x Continuous Rotation Servos
• 1x Meped/LittleBot PCB
• 1x Arduino Nano
• 1x HC-06 Bluetooth Module
• 1x Ultrasonic Sensor
• 1x 6v 4 AA Battery Holder

For the Gripper Addition

• MG90S Servo
• LittleBots Gripper Files

LittleBot Android App

All of these supplies can be purchased on the LittleBots Website

1. Insert the two continuous rotation servos into the base so that their wires feed out the back.
2. Secure with a single servo screw on the armature side of the servo. (you may use 2 screws, but they are not necessary)

Note: To help to get the wire started through the back hole you might use needle-nosed pliers rather than fingers

1. Insert the servo horn into the slot on each wheel. (Make sure that it is well seated)
2. Press the wheel onto the servo armature
3. Secure the wheel with the horn screw

Hot-glue the swivel piece to the center-rear of the base.

Note: The ability of the LittleBot to move over various surfaces is based on this swivel. The higher it is, and thus the farther forward he leans, the more weight on the drive wheels. But he can only lean so far forward before he is sucseptible to falling forward when someone throws him into revers quickly.

If, after assembly. your LittleBot doesn't seem to be getting very good traction. Apply a thicker layer of hot glue under it to tilt him forward slightly.

(FYI: Other ways to improve movement are hotglue treads on the wheels, and increasing the power to the wheels in the arduino software)

The Littlebot gripper can be assembled by following these instructions. The above photos are for reference.

1. Attach the finished gripper to the shell of the Littlebot by sliding it over the mounting nubs.
2. Feed the servo wire through the side slot.

To fit into the Littlebot the bluetooth module has to lay nearly flat against the PCB board. Use a pair of needle-nosed pliers to bend the leads. Be careful not to break them off.

Note: Make sure that you upload the Arduino Sketch to the Arduino before you plug in the bluetooth module. Bluetooth and USB interfere with each other. If the bluetooth is plugged in when the USB is plugged in the sketch will not upload.

Use 4 male-to-female jumper wires to connect the ultrasonic sensor to the Meped Board. Make sure that the wires connect to the same labeled locations on the sensor and and the board

Press the ultrasonic sensor into the eye holes of the head.

Use the wiring diagram to attach the servo and ultrasonic sensor.

1. Slide the board into the slots at the back of the base.You can secure the board with a servo mounting screw in the upper-righthand corner of the board if you want to.
2. Once you have secured the board. Plug in the Bluetooth module

Insert the battery pack into the slot in the center of the base.

Thread the battery lead through the top of the head and press the shell onto the base until it snaps into place.

And you are done assembling the LittleBot. Enjoy.

Program the LittleBot

The Littlebot code can be downloaded from the LittleBots website. Grab the latest version of Walter_OS.ino and the Android app for best results.

Notes:

1. Do not try to upload to the arduino when the bluetooth is connected. USB and Bluetooth cancel each other.
2. When using the app, make sure to pair the device to the LittleBot in settings first, then connect bluetooth when the app starts up, else the app may crash.

The App

Here is the Android App for controlling the different functions of the Littlebots

Parts and other Resources

All parts for the LittleBot that appear in the tutorial can be purchased from the LittleBots Store.

If you are more into watching video tutorials here is an option.