Pushbot Troubles

So, my team has decided to go with a pushbot, and in our opinion, it works great. The only problem that I see is sometimes stars will flip upwards and get stuck on the fence causing us to not be able to push under effectively. Now, I can simply back up and let the star fall so that I can push again, but I was wondering if anyone has any ideas on how to prevent the stars from getting stuck in the first place. Is there a way to build around it, or is this something where I just have to rely on good driving?

Do you have pictures of your bot?

Here are a couple of pictures. The front plate that we use to push was lower, but we decided to take some off of the bottom. We have weight in the front of the robot, right behind the front plate. Any ideas are appricieated. Thank you

Unfortunately, thats the one issue with pushbots. I can attest from experience that if you have the star oriented the wrong way, it wont go under. The stars are quite strange like that, and the only way to get around that is to move it so that it goes under. Try orienting the star so that 3 points are on the ground, that usually gets under the fence with no hassle.

@artsy.andrew We try to do that and it works fairly well. Usually, if we attempt to push 4 or more stars at a time, we will get at least one star stuck. Once we raised the front plate and moved our weight to the front, it happens at little less, but I dont have to much room to raise the front. Thank you.

From what I have seen, the most successful at getting stars under the fence have a pushing surface that will just barely fit under the fence. I would think that if the pushing surface was tilted with the top slightly more forward than the bottom, that would also help.

In your first picture, there was a lip like structure on the bottom. I wonder if it would work to have that on top to help push the tops of the stars forward.

If you try that, let me know how it works.

We had attempted having a lip structure on the top as well, but we had trouble with stars getting stuck to the lip, and it hadn’t made a big enough difference to keep on there. We had just taken the bot to a competition on the 14th. It worked well and we did well, but I definitely will attempt your idea with the angled plate. Thank you for the suggestion.

Would you happen to have any suggestion for a 1 motor mechanism to effective knock stars off of the fence? As of right now, we have a “windshield wiper” that isn’t as effective as we would have hoped it to be.

So you’ll ask the forums for help, but when I suggested you fix it…

Based on how much space you have on your robot right now, I think you would be well suited to build a linear lift to knock stars off the fence. Linear lifts can reach high enough to score off the fence easily, and if you build a wide beam on the top of it, then it could score multiple stars at once. Perhaps if you get it working well enough, you can expand it to be a hanging mechanism later on, as well.

@Infinity Minus 1 Thank you for the suggestion! My team discussed it, and we concluded that it was a good idea; however, we will not be able to do it. We only have 1 motor that we are willing to use, and we don’t see a possible way of creating an effective claw with one motor. We have 10 motors for the drive train, and 1 motor for an H-Drive. We do not feel like giving up the maneuverability for an extra motor is an effective strategy.

Later in the season, probably when we have more down time, we will revisit your claw idea.

I’ve seen a 1 motor claw do pretty well. You can try it out and see how it works.

@SMHSRobotics has also seen a 1 motor claw do pretty well, but he might not have realized it. Take a look at my team’s claw when you get the chance, @SMHSRobotics. It only uses one motor, and it has enough torque to carry basically as much as it needs. And you can always up the gear ratio if you don’t think it will work.

But like you said, it would be beneficial to wait until you get a good amount of time for trial and error between competitions.