Overview
RoboBall keeps its electronics inside an inflated shell and rolls by swinging a pendulum inside it. The soft shell changes how it rolls, but most models treat its contact with the ground as a single rigid point.
[04] Project
Hydroelastic Robot Ball Contact Simulation
DrakePythonURDFSolidWorksMeshCat
Contact modeling for RoboBall, a soft spherical robot driven by an internal pendulum, in Drake. Published in IEEE Robotics and Automation Letters, 2025.
- Role
- Co-author, IEEE RA-L
- Year
- 2025
- Published
- IEEE RA-L, 2025
- Robot
- Soft, pendulum-driven sphere
- Best model
- Hydroelastic contact
- SolidWorks model
- URDF
- Drake
- Ramp tests
How it works
We built a URDF of the robot from its SolidWorks model and added measured joint friction. The shell was then modeled with Drake's hydroelastic contact, which spreads contact over a pressure patch instead of a point, and compared with rigid point contact.
Result
In ramp tests at several shell pressures, the hydroelastic model predicted the robot's rolling speed most accurately. Point contact has no shell losses, so it rolled the simulated robot much faster than the real one.