Arduino Nano Quadruped Robot

My name is Jaylan and I made this project for my Principles of Engineering class with Ms. Berbawy. It took around 6 months to finish due to only working on it on some days of the week. This Instructable will go through my building process for creating the Arduino Quadruped.

I wanted to build this project after I saw a picture of a Minikame Quadruped in Hackspace Magazine. I also saw many other creations on Instructables like an QUATTRO created by Technovation and the 3D Printed Quadruped from Ijunqian. Throughout the whole process I referenced those websites to help me build my 8 DOF Quadruped Robot from scratch.

Special thanks to our POE teacher Ms. Berbawy!

The project was 3D printed so the body and the legs of the quadruped were all designed by me. Everything else was purchased on Amazon.

Whole Body:

• PLA Filament or PETG Filament
• Arduino Nano
• Arduino Nano Expansion Shield
• 8 MG996R 55g Metal Servo Motor
• M3 Screws (usually come with sg90 servos)
• Mophie Juice Pack Powerstation Pro (any compatible power source is fine)

Tools Used:

• Drill and drill bits

The body was 3D printed and made of PETG filament, which is stronger and more flexible than PLA. The body holds the Arduino Nano, the Arduino Nano Expansion Shield, and also has 4 slots on the sides where the servo motors are placed.

The legs of the quadruped also contain two separate parts, one being the hip joint and one being the foot of the leg. Each hip joint contains an additional servo to move the whole leg, with the servo on the body piece moving the legs forward and backward while the servo on the leg joint moves the foot up and down.

The legs of the quadruped are made of of PLA. I printed 1 body, 4 hip servos, and 4 foot pieces.

To connect all the leg pieces together and to the body, I attached servo horns to each of the hip and foot pieces so they can easily attach to the servos.

However, I did not create the screw holes for the attachment of the servo horns to the actual 3D printed pieces, so I had to manually drill holes into the hip and foot pieces, I would not recommend doing that if you can help it :). I used a normal power drill and used 1/16'' drill bits to drill the holes in the pieces.

I then used M3 screws that come from the packets of sg90 motors to screw the servo horns to the pieces. I had access to these screws since there were extras from my class. The screws were a tight fight in the drilled holes so it was able to hold the servo horns in place.

After finishing the drilling I installed all the servos into the slots and connected the pieces together to construct the framework of the whole body.

The next step of the process was to move all the servo wires into the required locations so that each of the motors can be controlled by the code that will be installed in the Arduino Nano. The wires of the servos all connect to the Expansion shield.

Where each wire connects is listed below:

• D2 to front right body servo
• D3 to front right hip servo
• D4 to back right body servo
• D5 to back right hip servo
• D6 to back left body servo
• D7 to back left hip servo
• D8 to front left body servo
• D9 to front left hip servo

After connecting the servos, all the difficult hardware is finished and the only thing to do is to upload the coding for the quadruped robot to move forward

The code that I used was made by Ijunqian who made the 3D Printed Quadruped that I modeled mine after. The coding was created to represent the creep gate movement, which allows the robot to steadily move forward in a walking motion.

To upload the code I used Arduino IDE and a USB mini cable that came with the Arduino Nano.

Now the Arduino Nano Quadruped Robot is almost finished. To allow the robot to move, all you need to add is a power source/power supply.

I used a Mophie Juice Pack Powerstation Pro as a mobile power supply. It is fairly light and can rest on top of the quadruped robot as it moves forward. The robot moves forward when the power supply is plugged in and stops moving after the disconnecting the power supply from the robot.

There were many failures and retries during the whole process. Most of the errors occurred during the coding of the robot and determining which servo was best suited for which location.

During one of the test runs of the robot's code, the code input to reangle the servo angles caused one of the hip pieces to split and create a small crack down the middle.

The leg pieces were also very thin which made the robot really fragile and caused me constant worry about it breaking due to the weight of the robot.

Another problem that later emerged was that because of the way the body was created, the servo slots were all angled towards one direction and hindered the rotation of two of the robot legs.

Lastly, two of the ports on the expansion shield did not work, and therefore two of the servos were unable to move at all, which affected the robots movement. The robot however was still able to move forward, but at a very slow pace.

That was how I created my Arduino Nano Quadruped Robot. I gained a lot of experience throughout the failures and successes of this project. By creating this robot, I was finally able to get a grasp on electronics and understand each and every component I had used throughout the project.

I hope you enjoyed this Instructable!