After some postseason testing I believe our team was incorrectly applying our vectored intake wheels (VIW). See the attached picture. I don’t believe we had them close enough together to be effective. I am thinking it is one of two modes of failure.
The intake goes too far over the ball and it struggles to jump between VIWs because of the downforce of the intake.
the angle we are hitting the ball on isn’t actually hitting the VIWs rollers.
The question I am posing, does anyone mode a resource on this, done significant testing, or have a rule of thumb on how close they should be?
I have a good amount of info on how to optimize the performance of these from developing the TTB design, to using them in 2020 and 2022. I will try to write something up in the next month or so; 8096 is very busy preparing for an offseason event at the beginning of November. I should be able to put some time into this after that.
We did a bit of testing / tuning of our vectored intakes in 2019 and 2020. There are a lot of factors that come into play, but I think our conclusions boil down to the following high level design factors:
The diagram that you are showing appears to be showing the intake positioned above the game piece and the floor below the game piece. There is a 3rd element in play which is a barrier of some sort that prevents the game piece from translating into the page due to the rotation of the VIWs and forces the mechanum rollers to push the game piece laterally instead of into the page. In most instances, this will be the bumper of the robot (you are translating the game piece along the bumper to a cutout where the next part of the intake mechanism takes over to pull the game piece into the robot). The geometry of the relative location of the bumper and the intake was fairly important. If you extend the intake too far out away from that bumper, or if your bumper is low relative to the center of the game piece, you create a gap between the intake and the bumper that is large enough for the game piece to get squeezed through. Not extending the intake out far enough results in the game piece not getting trapped by the 3 constraints (VIW, floor and bumper) and can escape out of the grasp of the intake. We found that, when the ball was being pressed against the bumper, the point where the VIWs contact the ball needed to be about 5 -10 degrees beyond the top of the ball in 2019. But this will be affected by the compressibility of the ball, the compressibility of the bumper the vertical location of the bumper relative to the size of the ball, etc. The critical point where you need to assess the ability of the ball to squeeze through the gap between the bumper and the intake is when the ball is straddling two VIWs as this is the point where the effective gap is the largest.
At the point where the contact with the game piece is handed off from one VIW to the next one, you want to ensure that you have good contact with the game piece by both VIWs at the same time. This is obviously affected by the spacing between the VIWs and the amount of compression of the game piece. The perhaps not so obvious factors that also affect this are the compression of the bumper noodles (assuming that the vectored intake is pushing the game piece against the bumper in order to produce the lateral motion) and the stiffness of the intake in terms of holding the compression the the game piece. This is the factor you are trying to diagram in your figures. But the “right answer” in terms of VIW spacing depends on the other factors described in item #1.
The speed of the intake seemed to play a fairly significant role in both the 2019 and 2020 intakes. In 2020 especially, the stickiness of the ball made it difficult to find an optimal speed to run the vectored intake in order to move the ball laterally without allowing the ball to roll under the bumper. The 2019 ball seemed to be a bit more forgiving in terms of speeds so I think this factor is also game piece specific and requires a level of tuning.
Mechanum wheel size. In 2019, we used 4" VEX mechanum wheels for out intake. In 2020 we used the 2" TTB mechanum wheels. We did not do any tuning with those sizes. They were basically what was available for each season. As it turns out, those choices offered roughly the same proportions of intake wheel size to game piece size. It also seems like many teams had good luck in 2022 with 4" wheels for their vectored intakes. I did not see very many intakes using 2" wheels this year (I’m sure they were out there), but as an observation, I would guess that larger wheels are going to work better with a larger game piece. But this is just a guess. Maybe others have some data to support this.
We did not do a vectored intake for 2022, so I don’t have a 3rd data point to offer for you. I suspect that the 2020 game piece was a bit of an outlier and that the lessons we learned in 2019 will be the most applicable to future vectored intake design / tuning.
