Robot Design

Chassis

Our chassis is inspired by the Ranger Bot [starter kit] chassis . We have a simple back wheel drive, which is useful for speed. We use 2 AndyMark motors with encoders to power the 2 rear wheels. In the front, we use 2 freely-moving omni wheels. We use 2 Expansion Hubs attached to the chassis. We have mounted one Expansion Hub on the top, and one at the bottom.

The Glyph Claw and Lift

Our claw is the "Secret Sauce" of the game. We use drawer channels to slide the claw up and down. It is powered by a single motor which powers a worm gear. As the worm gear turns, it rotates two spindles that pull the strings attached to our pulleys. With the strings attached to the bottom of the drawer slides, by coiling the sting up, this movement pulls the claw up. After verifying our lifting mechanism, we decided to focus on the grabbing aspect of our claw. Here is its evolution:

We first started of with a simple claw that opened and closed on glyphs. This was a problem because it posed a big problem to align glyphs in the correct orientation before picking them up [it cost us a lot of time], averaging about 3 - 4 glyphs per game (excluding autonomous).

Next, we changed to a gripper using wheels. This is super efficient because they can grab glyphs no matter where they are placed (even diagonally). This averages 5 - 8 glyphs per game (excluding autonomous).

We then moved on to mecanum wheels designed to suck in glyphs. Our main goal for this new design was to combine the two motions of sucking in the glyph (aligning it in the meantime) and propelling it up in the gripper (to make room for a second glyph) into one single action. This was designed to save a lot of time.

But, the new gripper prototype posed multiple problems:

The gripper couldn't suck in glyphs (align it) because we found that there was not enough friction. With a smooth surface and gaps in between each sub-section, the mecanum wheels were not efficient in this process.
This new gripper could not lift the glyphs up as we had previously hoped; there was too much friction with the glyph and the back of the claw. Also, the mecanum wheels were far apart, making it hard to maintain a hold on the glyph at all times.
Often times, the glyph would even slip off the top.

** we did not use this at competition.

After going to the competition and qualifying (we relied on our 2nd prototype), we were inspired to continue perfecting the mecanum wheel idea again.

To account for the sucking in problem, we put a regular wheel below the bottom mecanum wheel on both sides (we took these from our already working prototype #2), and now it works fine.

As for the issue with friction, we put Lego rollers in the back of the clamp, so the glyph effortlessly slides up, which works fine now as well.

Also, we added 2 more Mecanum wheels later, allowing us to keep the glyphs stable while we lifted them up.

Finally, to prevent glyphs from spilling over the top, we installed a simple metal piece to act as a stopper on the top of our forklift.

Using this design, we are averaging 9-10 glyphs per game (excluding autonomous).

Our YouTube Channel

We have prepared a few videos to help other teams competing in FTC Relic Recovery. You can find them at our YouTube channel at https://www.youtube.com/channel/UC3DDB6UykVp1qBA_KLCKNYg.

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