RD4B Not the best option

RD4B’s are big strong and effective but there’s one problem. Is their complexity effective in competitions? First of all the most effective RD4B’s have a chain bar at the very top which allows them to put cones on the mobile goal in one swift movement. The other RD4B’s have to put cones on the mobile which stays out in the field. The robots are getting faster but compared to RI3D’s “Ripper” they don’t stand a chance. The “Ripper” is complicated though but other simpler robots are out there. An example of one of these robots is OSIZR which is more efficient than an RD4B. You can check out RI3D and OSIZR on Youtube.

So you do have valid points. While i admit to what i’m calling an omni bot, “A bot that carries the mobile goal and stacks cones, predominantly a Dr4b”, is not the fastest at getting cones. The advantage that they bring are that they don’t have to reposition. They carry their MG with them so they just go to a cone and stack it. So it takes less time to become a good driver than another bot. This as well as the ability to go straight from stacking to putting the MG in the zone is a time saver. This year is all about time saving. The robot that is the best is not necessarily the fastest, but is will be the most efficient. The teams that can create a solid efficient robot will most likely win the most. I feel that this is the omni bot or some other hybrid of it. This is my opinion but I would like to hear other thoughts.

The terms everyone else has been using is
“internal stacker”
“external stacker”

Thanks Tabor. I’ve heard the terms but i’ve never made the connection.

I would agree there will more than likely be a design better than a RD4B and chain bar. It is hard to say for certain if designs like the Ripper could beat all RD4B, but I do think, in the end, the best design will most likely be something with a single “lift” as supposed to a RD4B and chain bar due to being easier for user control and programming. It will be interesting to see what is made in the future

There are many lifts that work better than a RD4B. People just like RD4B’s because of the height it gives you while also being linear. I would strongly suggest trying other lifts like elevators and cascading lifts and see if you can make one that’s close to if not faster than the Ripper’s speed. (Hint, it’s possible)

@902A Robotics you mentioned that Osizr, with a maximum cone hight of 8, would be a better option then a dr4b but if you look at the maximum scores of a match it doesnt appear so. A simple aspect to almost always winning a itz match is to score more than half the cones and get a goal in the 20 point zone. Because there are 80 cones on the field, it is best to score more than 40 per alliance to almost guanteee a victory. Thats only approx. 20 cones per robot and with the clearly superior internal stackers, thats 2 mobile goals per team as well. So my point is that it is neccessary to have a robot that can stack greater than 10 cones high in order to win a competitive match.

You have very good points about the ripper and ALBA. The ripper could score a cone and be ready to intake again in about 2 seconds, while ALBA was closer to 2.5 seconds. Many DR4Bs cannot match this speed.

However, I would disagree that DR4Bs are objectively worse than the ripper and ALBA. The main issue with your argument is that chain bars are indeed not very efficient, but there are plenty of other ways to achieve translation movement. Personally, I’ve seen side rollers, 4 bars, custom linear sliders, moving the mobile goal instead of the cone, and broken four bars (the gearing between the bars is removed, allowing each to be controlled independently and accomplish transitional movement) all match or exceed the speed of the ripper and ALBA.

Also, I’d like to point out that DR4B’s complexity is proven to be effective in competitions. DR4Bs excelled in skyrise, when fast linear motion was as important as this year, and 134D even got to semifinals at worlds with a DR4B in starstruck. Plenty of DR4Bs have already won competitions this year, and more will continue to do so as the season goes on.

I’d be very reluctant to test this sort of thing out. Elevator lifts have never matched the speeds of DR4Bs in past years, and there’s not a good way to power them with vex parts and low friction. I would say the main factor in determining how well a lift works is speed, and DR4Bs are simply the fastest linear lifts. Scissor lifts have a non linear power curve, elevator lifts have high friction, and 4 bars aren’t linear. People have achieved DR4B lifts that can go from resting position to 14 cones in as little as 0.5 seconds this season, and I haven’t seen any other lift even come close.

You do have a point, DR4B are the fastest linear lift, but i feel that the rippers low friction and low weight could possible beat a solid DR4B, and the chainbar possible but most likely will not beat the DR4B.

given the change in the height of the stack, this season we will need to look at the average cycle time.

Ripper is definitely faster in stacking, but the only down side is that you will need to tip the cone over before intaking it. And this will slow down the cycle time.

As for a standard dr4b with claw intake, you save time on the intake, but slower in terms of stacking speed.

As for alba - the main limitation is that it can only reach 6 cones high. Anything more will need an inclusion of a lifting system. And once you include a lift, then it is back to the same question - what lift to use.

This seems like a pretty interesting way on how to reduce that time:

Interesting… but… can it do match load?

You could just find a way to twist the input device 180 degrees while it’s moving on the chain (motor on the base of the claw for example).

But this is what I am trying to say - it is a 2 steps movement… tip the cone and then collect or turn your intake mechanisms around and then collect. Either way it will be slower than a normal claw intake.
But I have no doubt that ripper chain mechanism is faster than a dr4b.

I meant picking up an upright cone and rotating the input mechanism while it is moving on the chain (so no time is wasted)

A motor to rotate the input mechanism all on a chain?
I am not so sure about that…

To clarify, the ripper is not faster than a DR4B, but a ripper variant could be. The ripper takes about 2 seconds from intaking a cone to being ready to intake the next one. I’ve seen DR4Bs beat 1 second per cone. Further, everyone is right about the ripper needing to tip the cone, which at least slightly slows down the cycle time, and at most, is the main factor in the cycle time. That said, there are ripper variants and prototypes that do not need to tip the cone over before intaking, which seems to be the best idea. I know 60x has prototyped one, and 10N already released a reveal of a ripper variant that can intake cones upright. The ripper is theoretically the fastest and most space efficient lift, but the lack of rubber bands and necessity to go all the way over the top and back down in the RI3D results in a lower cycle time than a DR4B.

Back to the original question, I sincerely believe the robots that win worlds will all be DR4Bs. But I would have said catapult were the best design in SS and linear punchers in NBN, so I’m probably wrong. :slight_smile:

Linear punchers were actually rather good for shooting matchloads in NbN (see 400S). There is no single best design, usually.

I’m pretty sure that 10N made a DR4B

I think that DR4Bs might not be that good early season, but as State and Nationals come up, they might have an upper edge due to teams finishing really good prototypes. Yes, 10N did make a variant of a DR4B.