Background and summary of the invention
Robust actuation of spherical surfaces is very challenging as the entire surface of the sphere needs to be accessible for omnidirectional motion. Traction forces applied to the exterior surface of the sphere are used for actuation. Application of large actuation torques is especially challenging as slip often occurs, resulting in motion errors. The invention is a design for a ball drive that is able to hold onto a sphere using an adjustable magnetic force securely and enables the application of large traction forces for accurate omnidirectional actuation of the sphere.
An internal support structure with embedded magnets is placed inside of the spherical wheel, and the magnetic force is used to couple the spherical wheel to a pair of Omni-wheels. The Omni-wheels, which are mounted on an external yoke, are used to actuate the spherical wheel along the tangential direction. A second pair of Omni-wheels is also orthogonally mounted on the yoke and can be driven to actuate the spherical wheel along a second degree of freedom. A controllable magnetic force applied from the center of the yoke is used to couple the internal support structure to the chassis. The internal support structure, Omni-wheels, and magnetic coupling force work together to function as an omnidirectional axel for the spherical wheel. In addition to coupling the spherical wheel to the Omni-wheels the controllable magnetic force can also be adjusted to control the maximum traction forces that can be applied from the Omni-wheel to the spherical wheel, and from the spherical wheel to the ground.
Benefits
Our invention eliminates the need for the troublesome external support structure and instead uses magnetic forces to hold onto the spherical wheel securely. Additionally, we have the ability to adjust the magnetic coupling force enabling the ball drive to control the traction forces that can be applied during actuation minimizing the occurrence of slip. A large area of the spherical surface is also exposed, which allows for better ground traversal over uneven terrain, and the center of gravity of the ball drive is also lowered, which allows for better stability.
Exemplary Applications
The invention can be used as a drive system for mobile ground robots and vehicle that operate in dynamic or unstructured environments and require robust omnidirectional mobility.
Example 1:
Warehouse automation and logistics robots; mobile robots used in health care applications
Example 2:
Mobile remote presence robots
Example 3:
Entertainment robots (theme parks, consumer devices, automated camera dollies, etc.)
Example 4:
Small urban vehicles
Relevant Key Words
Spherical Wheel, Ball Drive, Mobile ground robot, Omnidirectional locomotion, Holonomic Motion, Maneuverability, Magnetic coupling, traction control, Spherical Surface control
Status
Available for Licensing and Research Support. Inquiries welcome.