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Bipedal Self-Balancing Robot

A self-balancing bipedal robot with 2-DOF legs and stepper-driven wheels, built from scratch with an ESP32 controller and dual IMUs.

  • Other
  • Open source
  • arduino
  • 3D printable

Suggested by Robotheca, created by @kairobyte (opens in a new tab), from github.com/kairobyte/bipedal_self_balance (opens in a new tab). Pinned to commit 9291561 (opens in a new tab).

Fork on GitHub (opens in a new tab)Download the files at this commit (.zip)
Hardware license
MIT (opens in a new tab)
Software license
MIT (opens in a new tab)
Commercial use
Allowed

Photo and 3D model

Bipedal Self-Balancing Robot, photo from its repository
Photo:@kairobyte (opens in a new tab)MITsource file (opens in a new tab)

3D preview converted from github.com/kairobyte/bipedal_self_balance at 9291561, under MIT. View the original files from GitHub (7.0 MB) (opens in a new tab)

Degrees of freedom
2

What it can do

Written by Robotheca from the project's documents.

  • Balances on two wheels as a self-balancing bipedal robot, currently for only a few seconds at a time.
  • Uses PID control running at roughly 1 kHz to keep balance.
  • Tuning parameters can be set over serial and saved without reflashing the ESP32.
  • Legs have 2 degrees of freedom for lean control.
  • Planned: PS4 controller support over Bluetooth and possible machine learning-based balancing.

Bill of materials

This repository has no parts list Robotheca can read yet.

Build guide

The creator's steps, each with its instructions.

  1. 1Model the parts in SolidWorks, building bottom-up from stepper holders to legs t
  2. 2Design the PCB schematic and layout, run DRC, and export Gerber files
  3. 33D print the parts and arrange them in the slicer
  4. 4Assemble the 3D printed parts and complete the wiring
  5. 5Flash the test code to confirm motors, sensors and RGB indicators work
  6. 6Tune the PID controller over serial until the robot balances

The guide appears here as you scroll.

Guide by @kairobyte (README.md), under MIT.

Wiring and electronics

Notes written by Robotheca from the project's documents.

Main parts

  • ESP32 as the main controller.
  • Dual IMUs, MPU6050 and MPU9250, for sensor redundancy.
  • A4988 stepper drivers controlling stepper motors that drive the wheels.
  • Servos for the legs.
  • Two buck converters stepping down 12V from a 3S LiPo battery, one for sensors and one for servos.
  • A capacitor and diode to protect the ESP32 from brownouts.

Connections

  • Two buck converters split power: one dedicated to sensors and one to servos, keeping noisy current away from sensor power.
  • A capacitor and diode are placed to guard the ESP32 against brownouts during high servo and stepper current draw.
  • Extra wires for the second leg degree of freedom were soldered directly onto the ESP32.