With Wheelbot, a research team from RWTH Aachen University and the Max Planck Institute for Intelligent Systems (MPI-IS) have developed a robot that, in the form of a symmetrical reaction wheel unicycle, moves autonomously on its wheel from any position. can stand. Minimal Robot is intended to act as a testing platform in research and teaching. It is easy to replicate due to its simple construction and use of 3D printed parts.
The research team’s wheelbarrow is only 22 cm long. When stationary, it consists of two wheels arranged vertically, which are offset from each other by 90 degrees. The robot rolls on a wheel. According to the paper published in IEEE Reaction and Automation Letters, the second wheel acts as a reaction wheel, controlled by electronics to ensure stable one-wheel balance. “The Wheelboat: A Jumping Reaction Wheel Unicycle” out.
build as simple as possible
“Previous unicycle robots have been designed to balance only in their upright balance position, which severely limits the capabilities of these systems,” explains René Geist, lead researcher of the Wheelbot project and team member of Professor Sebastian Trimpe at RWTH Aachen University. limits.” “To maximize the usefulness of a unicycle robot with reaction wheels, we decided that the wheelboat should be able to overcome a large enough disturbance, that it should have an integrated power supply to prevent cables from limiting its mobility. , and it should be able to correct itself even after tipping.”
The structure of the robot should be as simple as possible. So the research team decided to use the reaction wheel technology. Unlike gyroscopes for stabilization, this technology is inexpensive and the balancing torque is low compared to the reaction torque of the reaction wheel.
The robot then uses the reaction moments to stand up from any starting position, as the video (from 2:19) shows. During the process, the small, high-performance motor draws 16A at 24V. Researchers had to develop suitable controllers to control the motor because existing controllers were either too large or too weak. The research team also developed a “state estimator,” an algorithm that can estimate a robot’s roll and pitch angles. Four IMUs (Inertial Measurement Units) and wheel encoders provide the necessary data.
According to the research team, Wheelbot is the first unicycle robot that can efficiently “jump” on its wheels from any starting position. In addition, the Wheelbot is “a sophisticated test bench for robotic research”. Hence Wheelbot is suitable as a teaching and experimentation platform to introduce the students to robotics.
The next version of Wheelbot should be even easier to build and use. The science team wants to make robots more accessible. The Wheelbot V3 will be slightly smaller, have a more powerful microcontroller “and will be easier to use in terms of firmware design,” Geist promises. The team is also working on making the wheelboat roll on a predetermined track. After that he should also be able to perform agile driving maneuvers.
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