Teacher Team

Basketball Competition Robot

The Project:

We are designing a competition robot that will be able to pick balls up from the floor (Field) then load those balls into a catapult, which will shoot accurately enough to land the balls in a basket. The game will be 1 minute long and the team, or combination of teams who have the most balls in the basket after 1 minute is the winner. 

Enjoy the process of designing this robot with us - We will explain what we do and why.

The Wheel Assembly

1. The wheels are driven by 24 tooth gears and the motor is connected to a 36 tooth gear 

2. Gear ratio = 3:2 

3. Fast enough, but not too fast

4. Easy to control.

Specs:

Gear Ratio: 3:2

Wheel size: 200mm

Wheelbase: 141mm 

The Drivetrain

Note 

The robot is wider - to take more balls.

The brain is mounted upright at the back to give more space.

The sides have long beams for the roller that will collect balls from the floor.

The Intake - Roller

This is the part that will collect the balls

We used big sprockets (Gears used with chains) for the ends and made the collector almost as wide as the robot, so it would be easy to collect balls.

Then we stretched rubber bands over the two sprockets.

The rubber bands can stretch, which helps with grabbing onto the balls.

Frame for holding the roller

This frame allows us to position the roller correctly, so the robot can collect balls efficiently.

The frame also helps make the robot sturdier.

Mounting the Roller

We really had to spend some time to find the correct position for the roller, but now we think this is the best height. 

(It may change later though)

Powering the Roller

We decided to use a chain drive because it allows us to easily change the position of the roller. This would be MUCH harder if we used gears.

We also made this gear ratio 3:2, which means the roller spin 50% faster.

The Catapult "Puller" Gearbox

This is the most difficult part - Both to fit it in the available space, and to make it work efficiently.

The first part we made was the gearbox that will pull the catapult down. We had to make it small enough to fit into this space:

We only have 4 motors. That means there is only one motor left for the gearbox.

We'll use a knee action to pull and release the catapult

A gear ratio of 1:4 will increase the motor torque 4 times. (Small gear = 12 tooth and big gear = 48 tooth) We also doubled down on the gears (2 each) for more stability and symmetry.

This is the finished "puller" gearbox.

The Catapult

The catapult will be pulled down by the gearbox we just made, but the shooting power will come from rubber bands. The catapult also needs to fit between the intake roller in the front and the brain in the back.

It also needs to be wide enough for two balls

This is how we put it together.

The Code

First is the devices setup:

The devices and ports in the code need to be the same as on the physical robot.

Display the rotational degrees on the brain screen:

We'll need this information to stop the catapult (Shooter) motor at exactly the right place.