Wheels

Wheels are one of the easiest things to experiment with when building a robot. The type of wheel affects how the robot drives, turns, obtains game pieces, and handles how objects move within the robot.

AndyMark offers several wheel types that work with the standard 3/8" bore that is used in Robits.

• Stealth wheels work well for traditional tank drive bases, as well as launcher and intake wheels.

• Mecanum wheels increase maneuverability and can help with intake centering.

• Compliant wheels and stars intake and manipulate game pieces.

The Robits Core Kit includes examples of several of these wheels, including 3 inch Stealth Wheels, 3 inch Omni Wheels, and 2 inch Compliant Wheels.

Stealth Wheels

Stealth wheels are a good choice for a traditional drive base. They provide traction and are intended for robots that primarily move forward, backward, and turn by driving the left and right motors in opposite directions.

The Robits kit uses two 3 inch Stealth Wheels in the Robits Starter Drive Base example. This makes them a useful starting point for learning how a basic drivetrain works.

Stealth wheels can also be used in a launcher system as the point of contact with the object to be launched. Coupled with weighted flywheel inserts, stealth wheels are durable and just compliant enough to handle rigid or squishy game pieces.

Mecanum Wheels

Mecanum wheels allow a robot to move omnidirectionally - forward, backwards, and left to right without angling the entire robot. The Robits Mecanum Chassis is designed around this type of drivetrain.

A Mecanum drivetrain is a good choice for:

• Teams that have experience with maintence and software

• Robots that need precise positioning

• Tight or crowded playing fields

• Mechanisms where the robot needs to approach scoring locations from different angles

Mecanum wheels must be installed in the correct pattern. When viewed from above, the rollers should create an X pattern across the robot. The correct orientation is important. Installing the wheels incorrectly can prevent the drivetrain from producing the intended omnidirectional movement.

Omni Wheels

Omni wheels are similar to stealth wheels, but have rollers that reduce traction when the robot turns. The rollers allow the wheel to slide sideways easily, which make omni wheels particularly useful as support wheels on a traditional tank drivetrain.

Omni Wheels are a good choice for:

• Helping a robot turn more easily

• Reducing sideways friction

• Supporting mechanisms where the wheel needs to roll in one direction while allowing sideways movement

The Robits Core Kit includes 3 inch Omni Wheels, and the Robits Starter Drive Base uses omni wheels as part of its drivetrain design.

Compliant Wheels and Stars

Compliant wheels and stars are designed for interacting with objects rather than primarily driving the robot. They are soft and flexible compared with typical drivetrain wheels. When a compliant wheel contacts a game piece, it can deform around the object and provide a strong grip.

Compliant wheels and stars are a good choice for:

• Intaking a scoring element off the ground

• Transferring an object to a different area of the robot

• Ejecting a game element from the robot onto a scoring location

Compliant wheels, much like stealth wheels, can be used as the main contact point in a flywheel launcher system.