[Software]The Wheelbot: A symmetric unicycle with jumping reaction wheels

[SaLaH.]

Researchers at RWTH Aachen University in the team of Prof. Sebastian Trimpe and the Max Planck Institute for Intelligent Systems (MPI-IS) Stuttgart have recently developed the Wheelbot a symmetric reaction wheel unicycle that can autonomously jump onto its wheels from any initial position. This unique robot, introduced in a paper published in the IEEE Robotics and Automation Letters was fabricated using a combination of off-the-shelf and 3D printed components.

"Our research group works at the intersection between data science and engineering. One particular direction of our research focuses on combining insights from control theory with machine learning," René Geist, member in Trimpe's team in Aachen and lead researcher behind the Wheelbot, told Tech Xplore. "Testbeds such as pendulums, robot arms, and quadcopters, help us to check if the theoretical assumptions underlying an algorithm are practical in reality. Ideally, these testbeds are simple to use while being challenging to control with state-of-the-art algorithms, forcing us to think outside the box."

Two other examples of such testbeds are the so-called "Balancing Cube" and its descendant the "Cubli". These two systems have often helped to evaluate the effectiveness of network control systems and data-driven methods for achieving non-linear control.

 

The recent work by Trimpe, Geist and their colleagues builds on these previous efforts in the field. Their goal was to develop a minimalistic unicycle robot that could be used as a testbed by roboticists and computer scientists worldwide. To do this, Trimpe and his research group at RWTH Aachen University joined forces with Jonathan Fiene, head of the ZWE Robotics laboratory at the MPI-IS.

"Early on in the project, we opted for using brushless motors, as the ZWE robotics has plenty of experience using these in the open dynamic robot initiative, while prices for light-weight brushless motors dropped due to the widespread adaption of quadcopters in the consumer market," Geist explained. "When you look at a motor, arguably the simplest actuator one can come up with is to attach a wheel to it. If such a wheel touches the ground, we call it a 'rolling wheel', if it does not, we refer to it as a 'reaction wheel'."

Balancing a single-body, non-flying robot with the ability to drive and perform maneuvers generally requires a minimum of two wheels. These can either be rolling wheels, resulting in a Segway-like robot or a single rolling wheel and a reaction wheel, resulting in what is known as a "reaction wheel"—or "moment exchange'—unicycle robot.

Source:https://techxplore.com/news/2022-08-wheelbot-symmetric-unicycle-reaction-wheels.html