The Chassis or Drivetrain is the base or bottom of the robot. The chassis design can affect how the robot drives, scores, and moves around the field. A chassis can have the added benefit of protecting important and fragile parts like the motors, wiring and cortex. It can also prevent the robot from tipping over. To learn more about Chassis and Drivetrains, go to the VEX IQ Curriculum for Drivetrains.
There are some common chassis shapes that students build in VEX robotics. Each has pros and cons, so choose your chassis wisely. However, the most important thing to know is that the axles holding wheels or gears need support from both sides.
Otherwise, the axel will move on a pivot point like a teeter totter and with all that movement will not drive the way you want it to! Make sure you design and build like image that is shown above!
Square/ Rectangular Chassis
The square or rectangular shaped chassis is a sturdy structure that can handle a lot of stress from the mechanisms moving above. It also blocks the game pieces from entering the inside of the robot and getting stuck. Sometimes the square design can be used to push game pieces where you want them to go.
H- Shaped Chassis
The H-shaped chassis is another sturdy base and uses parts than the square or rectangular shaped chassis. It also allows areas for the others subsystems of the robot to operate in the front and back of the robot.
U-Shaped Chassis
The U-Shaped chassis loses a bit of structural integrity or strength along the front of the robot since most of the support is along the back. However, the benefit is that there is plenty of room for another subsystem of your robot to operate inside the U-shape or to bring game elements inside the robot.
Turning scrub is also something you will need to keep in mind. Turning scrub is the friction that resists turning. This friction is created from the wheels dragging sideways on the ground as a robot turns. Ideally, you want to reduce turning scrub in your design using Omni Directional wheels. However, there are some instances where friction may be beneficial.
The shape of the chassis also affects the turning scrub as shown below.