What is the best launcher. Give an argument, listing pros and cons, and provide evidence for your case. Just wondering what teams think is the best type of launcher for full court shots.
Full court shots? puncher, definitely. I have seen them shoot at 1 second per ball with just 2 motors, so, with a double puncher, you can easily shoot 2 balls per second with 100% accuracy. Now, I have see some unique catapult designs that rival the puncher, but I am assuming that you are referring to the typical wingus dingus style catapult, which isn’t quite as good for long range shots. However, this is considering only full court shots. If you consider short range as well, and you are only considering having one launcher, the flywheel is the best, because as it gets closer to the goal the fire rate increases and it becomes more accurate, while other launchers experience the exact opposite: less accuracy and a decreased fire rate.
Actually one ball per second is not extremely fast for a puncher. We had an old puncher shooting at 2 balls per second. The problem is not the speed with the puncher, but I believe it is the accuracy, as a puncher cannot always compensate ball compression. Also, a catapult with a cam can shoot balls at 1 per second, so dual catapults would be shooting at the same speed of the puncher you have managed.
This weekend we were practicing on our club’s field. It just happen that our sister team had just rebuilt their puncher and we done another iteration of our speed control algorithm for a single flywheel.
Their puncher uses low trajectory and fires directly into the high goal. We fire at the higher angle, such that it could both do full court shots and score into high goal from right in front of the goal bar.
So we put our robots in opposing corners, did a couple of aiming shots each and started shooting ball for ball.
They didn’t miss a single shot until one of their rubber bands snapped after 56’th ball. We continued to fire for a 100 ball test. Out of those 92 went into high goal, 5 bounced off the low edge of the high goal and 3 went into low goal. Our longest streak of hitting high goal in a row was 31 balls.
So it looks like well built puncher is much more accurate than flywheels, but they still don’t have solid strategy for shooting from up close and, I think, with few more iterations of our speed control we could achieve 95% accuracy from anywhere on the field.
And the final data point: they were using two motors to drive their puncher and we were testing single-motor design.
Yes, that is why I said “wingus dingus style catapult”. When you put a cam on a catapult it becomes more like a puncher in the fact that it cannot adjust the power of the shot like the typical catapult.
Wow, 92% with a one motor flywheel :O. What is your fire rate?
Wow! very impressive that you achieved that accuracy with one motor! i too would like to hear about your fire rate. So now that you have been able to achieve a single motor flywheel… might you start going and adding more motors now? Now that you have achieved incredible efficiency, if you add motors wouldn’t it just give you even more if an insanely fast recovery rate?
During those tests we were working on accuracy and efficiency and went a bit conservative on the fire rate. It was averaging about 3.5 sec per ball. After few more iterations on the speed control I would expect to be able to shoot every 3 sec, maybe 2.5 sec a ball if we are lucky.
The motor is running at about 85% of its nominal speed and we are commanding it at 90-110 power level, so there is some room to improve recovery time with a single motor, but not very much.
The launcher design has space for 3 more motors. And, since one motor is enough to compensate for flywheel friction, my best guess is that with two additional motors recovery time should be 0.5 sec or better.
Don’t forget that those aren’t the only options for a launcher. At the last tournament I was at, there was a team who had a very innovative catapult-puncher thing. It hit almost every shot and had a decently quick firing rate. It will be teams like this who excel beyond others because they aren’t going to have the same thing as everyone else. My money is on other launchers being the best.
Yeah, I think that catapult and puncher aren’t the best categories names to put non flywheel shooters into. Better categories would be constant contact and momentary contact (puncher) and subcategories being motor vs non-motor release mechanisms. Within non-motor release mechanisms would be all of the slip gears, nautilus cams, etc.
The shooter you choose really depends on if you’re going for accuracy or fire rate. We’re currently using a fly wheel, able to shoot full court, but we’re starting to experience stalling issuses. The good thing about the fly wheel is that it can shoot a good distance pretty quickly. A fly wheel can also be pretty compact, depending on how you design it. However, a fly wheel needs a lot of power to stay running for a whole match, and needs many motors to combat stalling. It is not very accurate on its range. After each shot, the wheel slows down, making the next ball fall short. A flywheel also applies a lot of spin to the ball, which could be good or bad.
A puncher or piston shooter leans more toward fire rate. They’re also very accurate, but their distance may change depending on the firmness of the ball. A piston shooter takes less power to run becuase it doesn’t need to carry as much weight as a fly wheel would, and most of its power will come for elestic bands or other form of resistance. A piston shooter is also light and compact. It might only take a few parts to make depending on how you design it. It also applies little to no spin on the ball.
A catapult trades fire rate for accuracy. You can be almost 100% accurate with a catapult. It does not rely on the ball’s firmness at all and chucks the ball at a consistent speed each time. Even though the catapult will shoot slower than other devices, it is deadly accurate, so you can almost assume those driver control loads are all going in.
Puncher for far shooting. One wheel flywheel for up-close shooting. 2Z and 2R style!
how do you adjust power with a catapult? Do you change the power when it goes foward?
Yeah, that how wingus dingus did it in their video back from the beginning of the season. Their full field shooter would use 127 power or something like that for full field shots and something less than 127 to slow down the catapult for close range shots.
I believe another advantage the catapult has is the amount of motors it uses. A catapult can powered with only one motor, providing yet another advantage to the catapult. Our catapult uses 1 HS motor, and our puncher uses 3 motors, so dual catapults would be much more feasible than dual punchers.
How far does your catapult shoot? Full/Half fields or right against bar?
full
Full court shots is the catapults we will use for our new design, but we previously had dual catapults (one shooting long and one shooting short).
LP’s FTW. 0.3 seconds per shot.
I think the different designs have different strengths. For up-close shooting, nothing rivals single/double flywheels because the ball does not need to settle and can be loaded directly into the launcher from the chain. For instance, has a crazy 0.125 second fire rate from right up close, and, due to a good chain system, they are able to feed the balls in at that speed. Another example is the blue robot during this video who has a very fast drive base, 0.4 second fire rate from up close, and very effective intake. Since balls have to settle into the puncher or catapult, and be fed in a separate motion from the chain, these designs tend to be less spectacular for up-close shooting, but they can of course be very effective since they do not need to shoot particularly far.
Then, for long-range shooting, IMO single flywheels and punchers are the best designs. This is a matter of hot debate, but punchers and catapults can often achieve the best accuracy. Catapults are theoretically more consistent because they do not compress the ball, but even the best catapults will miss 1-2 of the preloads due to a human error, slightly imperfect positioning, a particularly light or heavy ball, etc. Punchers are too imperfect, but by maximizing the area of contact against the ball, these punchers tend can achieve similar accuracy to that of the catapult. And note that this design can theoretically launch 4-5 balls per second but did not in the video because there was only one person loading preloads. Flywheels, although very difficult to build as such, can achieve equally high rates of accuracy and similar fire rates, such as Blank (do I really need a link?) or 323z Catapults, on the other hand, are just not able to keep up with the fire rate of punchers, while most other double punchers or catapults I’ve seen have very low accuracy when they’re firing at full speed.
My idea if I qualify for nationals or worlds and have enough time to rebuild (very unlikely) is to use a 5 motor transmission. The motors would either be able to go to a puncher that is able to fire full-court or a single flywheel that shoots from up against the bar. Then I would use the extra motor to have a really good intake and fast conveyor system. (4 on the drive) This is a bit crazy, but it is the most aggressive way I can see to optimize.
In any case, there are plenty of crappy full-court punchers and plenty of incredible full-court catapults. The most important thing is the quality of construction and the code.
Hope this helps. 
In my opinion, full field rate of fire will be the least important thing at worlds in the elimination rounds. I’m predicting that the field will be cleared in the first minute and a half, giving each alliance 30 seconds to get back to their loading zone, shoot all of their driver loads (which should take only 16 seconds if each robot has a 1 second per ball rate of fire), and lift. Now, I could be wrong in this prediction, but I think that it is the most likely scenario when all of the robots have taken the time to make their robot fast enough, flexible enough, and maneuverable enough to avoid any defensive robots as much as they need to in order to get 10-15 field balls scored. I do, however, think that there is a place for 0.25 seconds per ball full field fire rates, and that is driver and programming skills. I think that there will be incredible skills robots and incredible competition robots, but the two will seldom be seen in the same robot.
I agree during elims, if your robot can shoot the preloads in around 30 sec, then you should be fine. That is why I believe ultimately the best design is dual catapults firing at a rate of about 2 balls a second.