Motion

Transmitting Motion is the act of getting motion from one part of the robot to another using shafts, sprockets, gears, etc.

Transforming Motion is the act of changing the turning force (torque) and speed. Torque and speed are inverse to each other, meaning when one increases the other decreases.

The main structural component of the motion system are composed of shafts, gears, sprockets, and wheels.

Shafts

The core to transmitting motion in the REV Build System is the 6 mm Hex Shaft. This hex shape is incorporated into the other main motion components. Shafts are available in a number of different lengths, and can be cut to length if needed.

Using a hex shaft to transmit torque in the system removes the need for set screws, which can loosen over time and can damage shafts so that they become unusable.

Shaft Collars and Spacers

Shaft Collars

A shaft collar is a hollow cylinder with one or more set screws which tighten towards its center and an inner dimension that is just slightly larger than the shaft it is being used on.

Shaft collars are used to prevent lateral movement of a shaft or a component on the shaft.

Spacers

Spacers are used between parts on a shaft to take up the extra space and prevent the parts from sliding on the shaft.

When to use which?

• For larger sections of exposed shaft, shaft collars are preferred because installing multiple spacers is less efficient and is more difficult to manage during robot building and maintenance.

• For shorter shaft lengths, spacers are generally more efficient.

Gears, Sprockets, and Timing Belts

Gears and sprockets has their unique pros and cons.

Gears	Sprockets	Timing Belt
Can be used for changing rotation direction	Better for transmitting motion over long distances	Better for transmitting motion over long distances
More compact	Changing sprocket sizes requires changing the chain length	Changing pulley sizes requires changing the belt length
More flexibility in adjusting speed and torque	More forgiving in construction accuracy	Quieter and smoother transmission

Hubs

Hubs are used to increase the maximum torque of a component on the shaft.

Wheels

Traction Wheels

The traction wheels resemble standard wheels, like what you might see on a car or a bike

Omni Wheels

Omni wheels are a special kind of wheel that has smaller rollers around the circumference of the wheel. These rollers can passively roll perpendicularly to the direction the wheel is driven. This wheel makes it easier for a robot to turn in a differential drivetrain. Using Omni wheels in conjunction with each other can create more maneuverable robots in advanced drivetrain applications

Mecanum Wheels

The Mecanum Wheels have rollers around the whole circumference of the steel plate rim, set at a 45° angle. The full set of rollers present on the Mecanum Wheel remove the need to stack two wheels together like is required with the omni wheel.‌

Linear Motions

Linear motion can typically be defined as "straight line" or one-dimensional motion.