The Wheelbot
A jumping reaction wheel unicycle

A. René Geist, Naomi Tashiro, Zheng Jia, Jonathan Fiene, Sebastian Trimpe

Paper |    Video    |    Github

This work has been published in the IEEE Robotics and Automation Letters (RA-L) and was presented at IROS 2022

Abstract

Combining off-the-shelf components with basic 3D-printed parts, the Wheelbot is a symmetric reaction wheel unicycle that can jump onto its wheels from any initial position. With non-holonomic and under-actuated dynamics, as well as two coupled unstable degrees of freedom, the Wheelbot provides a challenging platform for nonlinear and data-driven control research. This paper presents the Wheelbot’s mechanical and electrical design, its estimation and control algorithms, as well as initial experiments for demonstrating both self-erection and disturbance rejection while balancing.


Key Features

The Wheelbot possesses over several unique features compared to other existing reaction wheel unicycle robots.

Symmetry

The design of the Wheelbot is symmetric such that its rolling wheel and reaction wheel are identical. In turn, both wheels can either act as rolling wheel or reaction wheel. From a practical point of view, such a design reduces the number of different 3D printed parts making it easier to build your own robot.

Roll-up

The Wheelbot can self-erect from any initial position using its rolling wheel which we call a "roll-up".


rollup1.mp4
Rollup2.mp4
rollup3.mp4

Stand-up

The Wheelbot can self-erect from any initial position using  its reaction wheel which  we call a "stand-up".


Dsc 1059.mp4
Dsc 1052 Standup4.mp4
Dsc 1056 Standup6.mp4


Robust & agile design

The Wheelbot's electronical and mechanical design combines brushless motors that have a high torque-to-weight ratio with compact wheels. In turn, the Wheelbot is able to reject considerable disturbances compared to previous reaction wheel unicycle robots that have been proposed in literature. 

Dsc 0879 Plane1.mp4
S01 Unicycle Pitch Acellerate Deccelerate.mp4
S01 Unicycle Slalom.mp4
S01 Unicycle Ballet.mp4

On-board power supply
& RF communication

The Wheelbot carries its own on-board power supply in form of four 3S LiPo batteries allowing cable-free balancing for up to 30 minutes. In addition, the robot communicates through an RF dongle with a computer such that it can be operated fully wirelessly.



Open source

Below you find files and code used to build
and operate the Wheelbot v2.5.



Further Resources

The  git repository of the Wheelbot project contains useful resources if you want to build your own Wheelbot.

If you have any questions, please feel encouraged to contact us.


FAQ

How much does a Wheelbot cost?

A Wheelbot costs currently around 600 €


How do I obtain a uDriver v.2?

You find  a detailed description on how to obtain the uDriver v2 on the github page of the open dynamic robot initiative.


Where do I find more details on the Maevarm M2?

You find more details on the Maevarm M2 here: https://medesign.seas.upenn.edu/index.php/Guides/MaEvArM

If the Maevarm M2 is not available in your region, you can use an "Arduino MICRO" which also uses an ATmega32U4 processor.


Contact