The FLL Robots need to do various tasks, typically by driving around on the table and lifting, pushing, pulling, grabbing, placing various small (LEGO) objects, with some degree of precision, and ocasionally latching onto fixed objects.
One important aspect is the rigidity of the main chassis, as well as of the support structure of its “arms”, or moving accessories.
We have learned, throughout the years, sometimes the hard way, that one of the ways to achieve that is to have a sort of interlocking construction. We do not rely on friction push-pegs alone, because eventually the beams would come off. We try to use L-shaped beams and rectangle beams to hold the various parts together.
Another aspect is how well balanced the robot is, how heavy overall and where is its center of mass. The brick is fairly heavy, so its placement is also important.
Putting the brick horizontally allows for easy manipulation, but uses a large surface, above which nothing can be set.
Putting the brick vertically, typically at the back of the robot, requires enough mass at its front to make it balanced, but offers much more space for various mechanisms.
Throughout these lessons we are going to present the details of our robot with a vertical control unit.
The main elements of this robot are
- a flat-interlocking chassis holding the two motors, the wheels and axles, and providing secure points to attach the upper parts
- a “backpack” structure to hold the brick
- two vertically-mounted rack-and-pinion systems, driven by vertically mounted medium motors
- front-mounted optical sensors on a mobile frame — the sensors can go up and down for obstacle crossing, as needed, being held down with a rubber band
- other passive and active attachments for various missions
We will go over its chassis and internal structure, and then describe various attachments we used in the 2020-2021 FLL season.