Over the past few days we have been hard at work iterating on our intake prototypes. We continued developing our side roller and flange grabber prototypes, as well as explored some new ideas.
We assembled our MDF prototype, which turned out to be quite large and hefty, and used a ratchet to mount it to our swerve drive base for testing. Although we were skeptical, the ratchet strap worked surprisingly well for keeping the intake in place. Initially we used a motor test rig to control all four motors, which inevitably led to quite a sketchy setup.
We eventually switched to running the motors straight off of the robot. With the adjustable design, we spent a good bit of time modifying the position of both sets of wheels and the back stop, as well as trying out different types of compliant wheels and playing around with the intake angle. The intake seemed to work well for the cone, but we couldn’t get the wheels to hold on to the cube after intaking it. To fix this we made the outer wheels constantly spin at a slow speed, which we found not only keeps the cube in place, but also helps guide the cone into the back wheels. We also swapped the outer set of wheels to smaller, more compliant wheels, which worked better with the cube. We were eventually able to run cycles with the robot, and the intake seemed to work fairly consistently.
With this design showing promise, we have started designing a next iteration made out of polycarb, which will be smaller and lighter than our current version. We are planning on putting the polycarb intake on the end of an arm that would attach to the swerve drivebase, and would be able to score both the hybrid and mid nodes.
We improved this design quite a bit over the past few days by finding ways to vector the cones into the middle of the intake. First, we added 3d printed mecanum wheels on the front roller and covered the back roller with duct tape because the rubber was too grippy and didn’t allow the cone to vector. We found that this worked pretty well.
For the next iteration we fully replaced the back roller with an ABS 3d printed corkscrew to help vector while gripping the feet of the cone better. We also slightly offset the rollers to the front one is higher than the back. The main problems we found with this roller was that the edges of the corkscrew were too sharp and the pitch was too low. Also, mounting it on the robot cart made it a little higher than we wanted. Overall, it was decent.
Attempting to solve these problems, we improved the corkscrew by increasing the pitch, blunting the edges, and increasing the diameter. We then CADded side plates and cut them out of MDF so we could keep the intake at an ideal height and wouldn’t need to use the robot cart anymore. This design unfortunately did not work very well as the compression of the flange was too high to work reliably. It only ended up working about 20% of the time, and was shredding up the cone a little.
To solve the problems of the previous iteration, we CADded and cut new plates that reduce the compression, slightly lower the rollers, and add space for another roller of 4” compliant wheels to go below the corkscrew. This additional roller is intended to help kick up the cone into the top two rollers. It is not built yet, but we have our plates cut and ready for Monday.
We played around with something similar to 4481’s “weed wacker” prototype to try to orient the cone in the same direction no matter its position. As expected, this worked best when approaching the cone straight on, and the effectiveness tapered off as the angle of the cone increased. This could potentially be something that is placed in front of an intake, to orient the cone in a position that the intake can pick up.
We also started working on a claw-style intake with 2 positions, one for a cone and one for a cube, using parts taken from the 2018 intake design. We started only using one set of wheels to prove the concept and had temporarily placed some surgical as a backplate so that the game piece doesn’t fall out. We played around with different piston sizes in order to find one that is the correct length and stronger than the tension of the surgical tubing. We found that this intake did a good job at holding on to the game pieces, although we may need to test out different compressions so that we can intake a game piece earlier. Next time, we want to add a second set of wheels and also mount this to the robot and test out different heights.
As always, if you have any questions or comments feel free to post here, or shoot me a PM.
-Aryan, @Advaith , @manthan , @Matthew3