Omni Wheel

A wheel ringed with small rollers that lets it roll forward normally but also slide sideways with no resistance.

An omni wheel has a ring of small, freely spinning rollers around its rim, with each roller's axis perpendicular to the wheel's own axle. Driven by a motor, the wheel rolls forward normally; under sideways force, the small rollers spin and let the wheel slide sideways with almost no resistance. Arranging three wheels at 120° to each other, or four wheels in a cross layout, and controlling each wheel's speed independently, lets a base translate in any direction on the floor while also rotating in place. Together with the Mecanum wheel, it's one of the two main omnidirectional-drive approaches: a Mecanum wheel's rollers sit at 45° with the wheels mounted parallel like a car's, while an omni wheel's rollers sit at 90°, requiring the wheels themselves to be mounted at an angle. Its downside is that the gaps between rollers cause vibration while driving, and its load capacity and ability to cross obstacles are limited, so it's best suited to smooth indoor floors.

ExampleRoboCup's Small Size League soccer robots commonly use a base built from four omni wheels, letting them translate sideways and spin while dribbling the ball.

Also called

Omnidirectional Wheel, Omni-Wheel

Related

Mecanum Wheel · Swerve Drive · Mobile Base (Chassis) · Differential Drive Base · Nonholonomic Constraint · Mobile Manipulation

Sources

Omni wheel - Wikipedia