4 inches wheels tank drive robot and docking the Charge Station

My team has been testing docking the Charge Station using 4’’ Colson wheels which has been going pretty badly, but we think that probably in the official Charge Station it would work relatively well, so we actually think that our Charge Station was built in a way that makes it impossible to dock it.

Here is a video of one of our tests

We would appreciate if you have any tests of docking it using 4’’ wheels in a tank drive robot reply this thread with a video of it or if you have any ideias about it!

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Hard to tell for sure, but it looks to me like you have a part of your frame hitting the ramp before the wheels. If that is happening, that might explain your problem.

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Have you tried a variety of speeds? I haven’t played around with the charge station much but I’d think at a lower speed you could have an easier time keeping the charge station down on your side

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Not sure if this is part of the problem but did you add the extra weight to the charge station?

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Check the angle of the ramp up - it should be 34 1/4 degrees. If it’s too much more than that, you won’t be able to get the robot on. Also, it looks like the wheels on your drivetrain are pretty close together compared to the edge of the frame, which could cause this.

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Try it without the bumpers. Is your frame hitting the ramp? If not, can you raise your bumpers up and still stay in the bumper zone? If none of that works you may need to consider moving those wheels closer to the edge or larger wheels, or a way to lower the wheels in relation to the frame.

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Yes we checked and infact it’s happening, now we are trying to come up with ideias to end our problem without having to use 6’’ wheels such as

We also had the ideia of placing a wheel in front of the robot tangent with the traction wheel so both are aligned with the ramp (posting an update about that as soon as we test it).

We weren’t using the 67 pounds as the manual asks, posting an update as soon as we test it

I hope you don’t have to resort to adding extra wheels for this, but I’ll be interested to see how it goes.

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We already measure it and it’s 34 degrees, and about the wheels being close together i’ve already approchead the topic in the other responses

The extra weight might help it tip a little slower giving you the clearance you need but it will definitely help with you not pushing the ramp which happens near the end of the posted video.

You also said in your post you were testing with colson wheels
image

I am 99% sure this is an omni wheel, however I can also see the other wheels are colsons. Now once again like adding the weight it may not make a difference but having your leading/all your wheels be colsons may help since they have a higher coefficient of friction.

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it looks like the bumpers/ fame is before the wheels if you could make the frame a bit higher at the front that would help. also the intake is hitting but it shouldn’t make much difference

We talked about it and did some calculations on this exact issue - and ended up deciding six inch wheels were the better choice for us this year.

Even if your bumper hits the ramp before your front wheels, the back wheels should still be able to push the robot up the ramp.

I think your bigger problem is with your Charge Station. If you go frame by frame, you can see when the robot first hits the side ramp it goes down into the ground, effectively making the angle the robot has to climb much larger. So instead of climbing it, it just pushes it backwards. If you fix that problem, you may find that your robot can climb the ramp okay.


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This is really our last hope with 4’’ wheels, the team was really excited about their conclusions because it makes sense, so we are going to test it tomorrow morning and I’ll give the update

It has been some time since the last update on the thread but I would like to show to the community our solution for this problem of going over the charger station with a 4" wheels tank drive robot.

Our solution was doing a chamfer on our drivetrain and an machined polyacetal filling the tube. This solved the problem of the diagonal of the tube hitting the ramp before our wheels that was the most critical part of the problem as you can see at the responses above.



This certainly was a differential of our robot that made possible to cycle like crazy through the charger station as you can see sometimes during this match

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We switched to 6in wheels because of this issue.

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