My team and I have made multiple rollers with braided rubber bands, mesh, etc. None have been able to pick up a cone when it is perfectly perpendicular to our intake. I can send pictures later today to help show my issue. Our roller consists of two rollers separated by 84 tooth gears. We have tried every size of sprocket. From what I have seen from many other teams everyone is using this spacing. The only thing we have yet to try is not using spacers to separate the sprockets and just using collars at each end to allow more of the cone to fit within the two rollers. We also have always used the maximum rubber bands on the sprockets (in between each teeth of the sprocket). If anyone could offer some insight into this it would really help us. Also if this is not a mechanical related problem with the robot let me know. We are using standard 393 motors and have tried high speed with our design. I have seen people have their rollers run continuously on low speed to help with driver control to allow picking up without having to always hold down a certain button. We do not use this but if this is the solution to the problem we would be glad to incorporate it.
We are team 4621B and we’ll see you guys at worlds
Thanks for the help
I’ve seen roller intakes with different spacing and yet most of the time spacing isn’t really the problem. I personally think that it is an issue with either the power/speed of the intaking or how you braided it. Yes, pictures will be very helpful for this topic
I’m sorry I am currently in school and am unable to send pictures. But I would say the sprockets are spaced out 7-9 inches and are being powered at 127 with standard vex motors. I have tried just using my hand before to push the cone in and it still falls out if I jerk it up like our lift and chain bar does.
I would recommend powering your rollers at a low power (10-15) once the cone is picked up to better hold your cone in, if this doesn’t fix the issue then it’s probably an issue with the rollers and pictures would help with that.
Another thing you could try is to reduce the spacing to be as minimal as possible, and cover your bands with non-slip mesh. This will provide a SUPER tight grip on the cone, enough that (at least in our case) it cannot hold a cone without having a PID activated (the cone forces the sprockets to spin and release it). If you have active control over the intake (i.e. it does not constantly spin), you can just make it spin at a constant power of 15-20 while not being moved, which would have the same effect. While this isn’t the best solution, and other teams have obviously built consistent rollers that do not require constant power, it works well for us. If we take the mesh off, it works REALLY well, holding the cone tightly on its own, but will sometimes fling the cone sideways when we drop it (we have a rather large drop onto the mogo for the first two cones, so we cannot have any inconstancy on the straightness of the cone).
We have an encoder that measures velocity. By default it runs at full speed (turbo motor). When the velocity drops to around 0 (it has a cone and can’t pull it in anymore), it stops spinning and activates the PID. It actually works really well cause it almost impossible to pull the cone out yourself unless you shut the bot off, but once you do the cone falls on its own, which has helped us out a few times (match ends, cone falls out of goliath onto stack).
