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FLL EV3 Robot

This blog post is about our current EV3 robot we're planning to use in the 2023/2024 FLL competition. Some features: 2 large motors for steering. 2 medium motors for attachments.  2 colour sensors for picking up the white and black lines, also used for line squaring. 1 gyro sensor. To enable attachments to be changed as quickly as possible we're using gravity to keep the gears connected, i.e. you don't need to fasten anything to the robot. Every attachment has 2x 12 tooth double bevel gear (part 32270) which comes in contact with the 2x 20 tooth double bevel gears (part 32269) on the robot. The medium motors are horizontally aligned on the robots, but we use 12 tooth double bevel gears to convert that to vertical alignments. These in turn are connected to 20 tooth double bevel gears, and the attachments in turn connect to these 20 tooth double bevel gears with their 12 tooth double bevel gears.  The complete robot is modelled in Bricklink Studio 2 . You can download the rob
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FLL EV3 motor attachments

One of the FLL rules says you can only use 4 motors in total. Typically you would have 2 motors for steering, which leaves you with 2 motors for all your missions.

Since different missions would require different usages of the motors, you can build different attachments, but you will need a way to couple your attachments to the motors.

I think the best way is to build something where you use a 20 tooth double bevel gear (part 32269) on the motor, and put that gear on one side of a 7x5 frame. Repeat that for the other motor and join them together, and fix it to your robot:


For attachments you need to build a frame than can be pushed onto the system above. You can use a 12 tooth double bevel gear (part 32270) which slide into contact with the 20 tooth gear on the robot. There should be a guiding hole on the robot side (done above with the 5 beam on the other side of the 7x5 frame).


Once you have this you can use the axles on the other side to do whatever you need to do with your attachment.



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