Introduction: Build Your Own Pet Demon Desktop Robot: KABANDHA

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About: As I dive deeper into the fascinating realm of robotics, I can't help but feel a surge of excitement and curiosity with every new concept I uncover!
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Meet KABANDHA, your personal pet demon robot inspired by the single-eyed, arm-bearing demon from the Ramayana. In this project, you'll bring this legendary figure to life as a fun, interactive desktop robot. Powered by microcontrollers, KABANDHA has a glowing eye and movable arms, making it a unique companion that’s both playful and tech-savvy.

This guide will walk you through building KABANDHA, using simple electronics. Whether you're new to robotics or an experienced maker, this project is designed to be approachable and rewarding. With motors controlled by a microcontroller, LEDs for the eye, and flexible arms, KABANDHA is more than just a robot—it's your very own mythical assistant. This instructable is inspired by the robotics projects of The Yantracharya, who has simplified complex builds for creators of all skill levels.

Let’s dive into how you can create KABANDHA and show off your pet demon with pride!

Supplies

Materials Needed:

  1. OLED Display (for the eye)
  2. DRV8833 Motor Driver
  3. 2 x Arduino Nano
  4. 7.4V LiPo Battery
  5. Connecting Wires
  6. Breadboard
  7. Perforated Prototyping Board
  8. 4 x N20 Motors
  9. N20 Motor Wheels
  10. Servo Motor (for the arms)
  11. HC-05 Bluetooth Module
  12. Male & Female Header Pins

Hardware:

  1. 5mm Sunboard for Chassis
  2. Thick Sheet for Canopy
  3. Tiny Screws

Tools:

  1. Soldering Iron
  2. Solder Paste
  3. Hot Glue Gun
  4. Super Glue
  5. Cutting Hobby Knife
  6. Screwdriver
  7. Wrench Set
  8. Wire Stripper and Cutter
  9. Computer with the Arduino IDE Installed

Step 1: Design Overview of KABANDHA

KABANDHA takes inspiration from an ancient demon known for its terrifying single eye and long arms. In this robotic version, we’ll replicate that using simple electronics and a lightweight sunboard structure. The robot will feature:

  1. A glowing eye powered by LEDs.
  2. Moveable arms controlled by a servo motor.
  3. Mobility provided by four N20 motors and wheels.

Using Arduino Nano microcontrollers, KABANDHA will be able to interact with its surroundings via Bluetooth, making it more than just a static model.

Step 2: Reason of Using Two Microcontrollers

To manage KABANDHA's various functions, we’ll be using two Arduino Nano microcontrollers. Here’s why:

  1. Microcontroller 1 (Motion Control): This will handle the movement of the robot’s wheels and arms, managing the motor drivers and the servo.
  2. Microcontroller 2 (Communication and Display): This will manage communication through the HC-05 Bluetooth module and control the OLED display. By splitting these functions, we ensure smoother performance and reduce potential delays or conflicts in managing different processes.

Using two microcontrollers allows us to efficiently handle both the motor and communication functions simultaneously, giving KABANDHA smooth mobility and interactive features.

Step 3: Designing the Body Using Sunboard

Instead of 3D printing, we’ll be using 5mm sunboard, a durable, lightweight material that’s easy to cut and shape. Follow these steps to design the body and canopy:

  1. Mark the Pieces: Using a ruler and pencil, mark out the main body, arms, and canopy components on the sunboard.
  2. Cut the Pieces: Use a sharp cutting hobby knife to carefully cut out the marked shapes. Be patient and ensure smooth, clean cuts for a good fit later.
  3. Drill Holes: If needed, use a small drill to create holes for screws and wiring. The holes should align with where the motors, servos, and electronics will be mounted.

Templates or exact measurements are provided, allowing you to cut out each piece with precision.

(10CM)X(6CM)X(8CM)

Step 4: Assembling the Sunboard Chassis and Canopy

With the body and canopy pieces cut, you’ll now start assembling:

  1. Step 1: Use hot glue or super glue to attach the chassis parts together. Start with the main body frame, ensuring all sides are well aligned.
  2. Step 2: Attach the canopy to the top, allowing space for the OLED display to be visible. The arms should have slots where the servo motor will fit for movement.
  3. Step 3: Use tiny screws to secure the more delicate parts, such as the motor mounts and servo placements. Reinforce with glue where necessary for added strength.

Ensure the components are well-balanced and that all the necessary areas for the motors and electronics are accessible.

Step 5: Wiring and Electronics: Connecting Two Arduinos

Now it’s time to wire the electronics and microcontrollers:


  1. Microcontroller 1 (Motion Control): This will be connected to the DRV8833 motor driver, which controls the four N20 motors. You’ll also connect the servo motor that controls KABANDHA's arms.
  2. Microcontroller 2 (Communication and Display): This will handle the HC-05 Bluetooth module for wireless control and the OLED display for any visual outputs. You can wire this to a perforated prototyping board to simplify the connection.
  3. Power Supply: Both microcontrollers will be powered by the 7.4V LiPo battery, with connections to the battery management system to ensure safe charging and discharging.

Use a breadboard to lay out the connections and refer to a wiring diagram for clarity.

Step 6: Programming the Arduino Nano

Once the wiring is complete, you’ll need to upload the appropriate code to each Arduino Nano:

  1. Microcontroller 1 Code: The code here will control the motors and servos. This includes forward, backward, and turning movements for the wheels, as well as arm movements.
  2. Microcontroller 2 Code: This will handle Bluetooth communication and the OLED display. You’ll be able to control KABANDHA remotely via Bluetooth, and the OLED will display simple messages or status updates.

GET CODE HERE[LINK]👈.

Step 7: Attaching Motors and Final Assembly

Once the electronics are set up, it’s time to mount everything:

  1. Mount the Motors: Attach the four N20 motors to the bottom of the chassis using screws. Make sure the wheels are securely connected to the motor shafts.
  2. Attach the Servo: The servo motor that moves the arms should be mounted inside the chassis, connected to the arm slots. Use screws and hot glue to secure it in place.
  3. Fix the OLED Display: Mount the OLED display to the front of KABANDHA, just below the canopy, so it’s clearly visible.

Ensure all components are securely fastened, and test the robot’s balance to prevent toppling during operation.

Step 8: Final Wiring, Power, and Testing

Before running the robot, check all wiring:

  1. Step 1: Ensure the power from the LiPo battery is correctly connected to both microcontrollers.
  2. Step 2: Check the connections for the motors, servo, and Bluetooth module.
  3. Step 3: Power on the system and test the Bluetooth connection by pairing it with your phone or computer. Use the provided controls to test motor movements, arm actions, and the LED eye.

If any issues arise, double-check the wiring diagram and test each component individually.

Step 9: Customization and Enhancements

Once KABANDHA is functioning properly, you can add custom features:

  1. Change the color of the LED eye by using RGB LEDs.
  2. Add sensors (e.g., motion or light sensors) to make KABANDHA more interactive.
  3. Customize the code to enable more complex movements or interactions.

You can also paint or decorate the sunboard body to give your pet demon robot a more personal touch!


HAPPY MAKINGS!!