Since we will have to make a robot that will extend really high, tipping over will be a major problem. Have any of you brilliant engineers:cool: designed an anti-tipping system yet?
During Sack Attack, our team had some major problems with tipping. We found that the closer to the ground as well as the closer to the center you could place the majority of the weight of the robot, the less likely you were to tip over. However, for Skyrise, I don’t think that just weight distribution will be enough. During Toss Up we used small bogey wheels in the rear of the robot to catch the robot as it leaned back, however I had thought about a potential mechanism that moved out from the back corners of the robot once the lift reached a certain height, stopping the chassis and bracing the ground, almost like support beams. That’s just one of the ideas though!
I had 2 ideas.
I was thinking of adding stand-offs onto hinges and have them hanging on the bottom of the drive chain. But I realized that there was no way I could lock them down. They basically would be there just to take up space.
My second idea was to have a rail system inside the drive chain so that once the arms (either scissor or danny lift) reach a certain height, the rails would start coming out of the sides. This way, there would sort of be a locking mechanism, so that it doesn’t come down, and it would stop it from falling on the sides.
I still am trying to find a way to stop it from tilting back and forwards. I do have to give credit to VEX, they are coming up with some really complicated challenges!
It’s a good idea to find good ways to prevent tipping, but in the event that tipping does happen, where does the team go from there? With as tall as some robots are going to reach, falling horizontally could mean instant wallbot! There’s also a slight possibility that teams might design a tipping rectification system (hint)
Anti-tip wheels which flip out the back like shown in this video.
Well, considering that it looks like the standard “six-bar” that we saw back through Gateway until Toss-Up has ended, it seems as if the Scissor will reign this year.
Just from my experience, I know there are ways that the scissor itself can be the anti-tip. Ive Seen it happen, and it works. If we look at how the scissor moves, and we use the OLD linear slides (the whole length), I’m sure you guys can figure it out.
(P.S. I could show a picture, but thats not the true spirit of Innovation, and invention. How can we expect to do things differently and help solve problems, if we all have the same solution. Im not trying to make this into a Rant, I’m just saying that I discovered something, and I gave blueprints, its up to you if you want to build on to it, don’t stop innovating)
I know exactly what you mean. Our team is bustling with ideas and we already have a solid design idea but we probably won’t do a reveal for a long while…maybe after we qualify for State Championship and Worlds. (And it’s not like myself or any other teams are afraid that others will be copycats and steal all of another team’s good ideas), it’s all in the spirit of allowing teams to innovate and figure out the way to do it on their own. Same reason students don’t directly post their driver->autonomous writing codes, to provide a good example.
I know exactly what you are talking about, 1412A. I won’t reveal it, figure it out yourself
One of our other teams came up with a really simple anti-tip using a T-shaped arm that was rubber-banded to pop out once the robot drove forwards at the start of the match. It was held in place by nylon rope tethers to keep it from swinging out too far, but it provided a safe wheelie bar that they could lean back on, and it took up virtually no space at all and was extremely simple. It might not work for super-tall bots, though, since as the arm swings it allows the robot to tip back further. But if it did tip back, all they had to do was lower the lift and they would tilt forwards again.
Our scissor lift used anti-tip wheels actuated on linear slides that went out in proportion to the lift height. Our current 8 bar that will compete in Killeen this weekend and Hawaii this summer uses an accelerometer to keep from tipping much like a Segway does. We will use an accelerometer on our Skyrise robot to prevent tipping as well.
How does that accelerometer work for you? I was thinking of using a gyro mounted at 90 degrees but now I’m wondering if the accelerometer would be a better choice.
Swift movements may be a must in this upcoming game. Granted, you don’t really need to move all over the field this time around. But when you’re in those tense I need to descore or else I’m screwed situations, tipping will certainly be a problem. Rollbars with wheels might be a viable solution, being ejected with a rubber band mechanism at the beginning of the match. What’s really intriguing me is that idea some had up there, using sensors to control these types of things. I have no experience with the latter, which would be the best choice?
I was thinking something like two half-circles would come out of the back of our robot, and they would have standoffs on them to prevent tipping. In any case, we might have to have anti-tip bars on the sides as well…
I might try to design “legs” to come out and stabilize the robot, just like the stabilizers on a mobile crane
I did some worst case scenario calculations yesterday. Assuming your center of gravity is about 43" high (I forgot why I used it, i know I took half of something then considered weight of cubes or what not*) and perfectly centered, you would need a 36" wheel base to have a 6 inch tipping clearance (6 inches because 4 or 2 inches isn’t really noticeable and doesn’t give enough reaction time from the driver station).
Because of this, you may need to resort to sensors, like the accelerometer or the gyro as mentioned, or a series of limit switches which force the drive in the direction that’s triggered.
If you want to do calculations yourself, make a triangle. The height would represent the height of the center of gravity. the bottom leg represents half of the wheel base. Use trig functions to determine the angle of where the bottom leg meets the hypotenuse. Use that to find the complementary angle. Using that angle and another trig function allows you to find the height which your front wheel will be off the ground. the idea is that the supplementary angle is the angle where the center of gravity is just over the polygon of support. Once it passes it completely, the robot will tip*
What about that little pneumatic trick we discussed about? I believe that 4080 mentioned that they used that in sack attack. You connect two double acting pistons together so one moves as the other one is moved. If we use this mechanism to extend anti-tipping bar when the lift is raised, it will certainly save space for the field that is about to be fully packed with cubes.
Edit: you might store some more air with this little mechanism!
The pneumatic idea sounds great! As of now, I dont have a robot to test any of these systems…yet
I was thinking that you may need a wheelie bar for the front and the back, because with the linear lifts people will push you from the front or back.
Won’t the front wheelie bar get into the way of your scoring in general? When scoring cubes on poles i think front wheelie bars will interfere more than help. But something like elastic assisted wheelie bar that automatically squeezes folded to save space when you are scoring on the poles might be better.
Here is one of our anti-tip wheels during the Sack Attack season. I will look to see if I can find a video of the pneumatic cylinder powered one as well.