The Wheelbot
A jumping reaction wheel unicycle
A. René Geist, Naomi Tashiro, Zheng Jia, Jonathan Fiene, Sebastian Trimpe
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".
Stand-up
The Wheelbot can self-erect from any initial position using its reaction wheel which we call a "stand-up".
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.
On-board power supply
& RF communication
& 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 €
2 x Antigravity T-motors MN6007 Kv160, 120€
2 x Encoder , 40€
1 x uDriver v.2, 100€
4 x IMUs, 15€
1 x motherboard + Maevarm M2 + Rf module, 50€
50 € for 3D printed parts, cables, laser cut copper rings
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.