# of Totes WORTH Stacking?

[kachea716]

How necessary is it to build tall stacks of totes? Yes, a 6 stack of totes with a filled container is nice (42 points?), but versus for example, doing two 3 stacks w/ a filled container (48 points?).... is it worth it? What is your team thinking? :ahh:

[AllenGregoryIV]

Last night in our blog we posted reasoning for the exact elevation we are trying to lift and stack.

http://blog.spectrum3847.org/2015/01/day-4-more-prototyping-and-4-bar-cad.html

Summary, lift should be able to elevate an object 4.5ft. Allows you to stack a tote on top of 3 totes on the step and allows you to put a container on top of 4 totes if you are grabbing it by the lip.

[Ginger Power]

How necessary is it to build tall stacks of totes? Yes, a 6 stack of totes with a filled container is nice (42 points?), but versus for example, doing two 3 stacks w/ a filled container (24 points?).... is it worth it? What is your team thinking? :ahh:

It depends on a lot of variables. Most important is how good you and your alliance partners are. When The GreenHorns and 'Snow Problem played a few matches together we found that 4 totes seemed to be the most efficient to stack for our particular robots. We both have what I would call lower-middle tier robots you would find at a competiton. That is to say, it's doubtful that we would make it to the Playoffs at a large event. If the functionality of the three robots is pretty low I would make stacks of 3. If it's pretty high I would make stacks of 5. Stacks of 6 with a recycling bin just gets dangerous IMHO.

[Zebra_Fact_Man]

Stacking 2 stacks of 3 may actually be quicker than 1 stack of 6, but there are only 7 totes available to each alliance (4 are shared), and if an alliance can average 1 stack of 6/robot/minute (which seems very reasonable for playoff alliances) you're going to run out of recycle containers awfully quick if you go only 3 high.

Maximize each container's value; go the distance.

[kachea716]

Stacking 2 stacks of 3 may actually be quicker than 1 stack of 6, but there are only 7 totes available to each alliance (4 are shared), and if an alliance can average 1 stack of 6/robot/minute (which seems very reasonable for playoff alliances) you're going to run out of recycle containers awfully quick if you go only 3 high.

Maximize each container's value; go the distance.

But, if you have a mechanism that can take all four recycling containers to your side.. you potentially can get 168 points jut from complete 3 stacks w/ filled containers :yikes:

[kachea716]

If it's pretty high I would make stacks of 5. Stacks of 6 with a recycling bin just gets dangerous IMHO.

I agree... in this game it's important not to play against yourself = make obstacles for your self.

[cjl2625]

I'm thinking 5 or 6, but not sure which.
I personally think the main problem with stacking 6 is that if you want to hold six totes plus a container on your robot, any appendages that high get dangerously close to the 78" height limit.

[MrJohnston]

It's going to be five or six at the highest levels.. Most likely, all bins will be scored on tall stacks in these matches. So, it would seem the tallest stacks are best... However, as robots cannot be taller than 6'6" and a bin on top of six totes will almost entirely be above the maximum robot height: A stack of 6 totes is just over 6' and needed to be lifted at least 2" to place them in a scoring zone. This leaves a whopping 4" of recycling bin below the robot height limit.

This introduces a challenging engineering problem. Do you find a way to grab the bottom few inches of a bin? Or, do you rely on a very smooth riding robot and a skillful enough driver to not "bump" anything? I have not yet fully solved this "difficulty." However, it could very well be that for nearly every (every?) robot it is so much more efficient to maximize stacks at 5 totes and a bin...

Of course, you then have to ask the value of taking a moment to stick pool noodles into the recycling bins...

[cadandcookies]

It's going to be five or six at the highest levels.. Most likely, all bins will be scored on tall stacks in these matches. So, it would seem the tallest stacks are best... However, as robots cannot be taller than 6'6" and a bin on top of six totes will almost entirely be above the maximum robot height: A stack of 6 totes is just over 6' and needed to be lifted at least 2" to place them in a scoring zone. This leaves a whopping 4" of recycling bin below the robot height limit.

This introduces a challenging engineering problem. Do you find a way to grab the bottom few inches of a bin? Or, do you rely on a very smooth riding robot and a skillful enough driver to not "bump" anything? I have not yet fully solved this "difficulty." However, it could very well be that for nearly every (every?) robot it is so much more efficient to maximize stacks at 5 totes and a bin...

Of course, you then have to ask the value of taking a moment to stick pool noodles into the recycling bins...

You can also stack a tote with a bin on top of it on top of 5 totes. Or two totes and a bin on top of four.

[asid61]

Einstein will be all six stackers or two six stackers and a noodler with peripherals. Or six stackers with noodler abilities. However, looking at a point chart. four totes gets you almost as much as five anyway if you can noodle it.

To stack, simply lift an existing stack and slide a tote underneath it. Most forked lifters should be able to do this to get very high stacks up to six plus bins without issues.

[orangemoore]

This year scoring is LINEAR, So it doesn't matter how high you stack for the bonus points as long as you stack the same amount of grey totes and place a recycling bin on top it will be the same. So then the question become well if I am only guaranteed 3 recycling bins how many grey totes can I stack? 12 in 3 stacks of 4 or 2 stacks of 6.

The answer to the question I think is based on your capability to score fast. If you can't score fast you can stack more smaller stacks versus larger stacks.

[kachea716]

It's going to be five or six at the highest levels.. Most likely, all bins will be scored on tall stacks in these matches. So, it would seem the tallest stacks are best... However, as robots cannot be taller than 6'6" and a bin on top of six totes will almost entirely be above the maximum robot height: A stack of 6 totes is just over 6' and needed to be lifted at least 2" to place them in a scoring zone. This leaves a whopping 4" of recycling bin below the robot height limit.

This introduces a challenging engineering problem. Do you find a way to grab the bottom few inches of a bin? Or, do you rely on a very smooth riding robot and a skillful enough driver to not "bump" anything? I have not yet fully solved this "difficulty."

You can also stack a tote with a bin on top of it on top of 5 totes. Or two totes and a bin on top of four.

That's a good idea, stacking a tote and a container at the same time will keep your mechanism within the height restriction!

[kachea716]

To stack, simply lift an existing stack and slide a tote underneath it. Most forked lifters should be able to do this to get very high stacks up to six plus bins without issues.

Stabilizing the container would become a problem with this? Raising the large stacks and keeping it balanced could be a problem. It's all about control.

[cadandcookies]

Stabilizing the container would become a problem with this? Raising the large stacks and keeping it balanced could be a problem. It's all about control.

This year is full of problems like this. Stacking totes "nicely" is far more difficult than just stacking them.

[asid61]

Stabilizing the container would become a problem with this? Raising the large stacks and keeping it balanced could be a problem. It's all about control.

It's a lot easier to keep an established stack stable than to keep it stable and have to place a tote on top of it. I'm not saying stability isn't a problem, but at least you don't have to lift very high.

[CalTran]

I think that it really depends on what kind of manipulator you end up building, and what sort of alliance you end up with. If you have a robot that can only stack from the bottom (As in lift stack, insert tote on bottom, place, repeat) then it's probably best to aim for 4-6 and maximize from there, but if you have a robot that can build stacks top down, then it might be more advantageous for your robot to move around and "cap" existing stacks with a container. If you're the only robot that can quickly stack, you might just want to go with 3-tote-container stacks and then score as many totes as you can after that.

[Caleb Sykes]

When The GreenHorns and 'Snow Problem played a few matches together we found that 4 totes seemed to be the most efficient to stack for our particular robots. We both have what I would call lower-middle tier robots you would find at a competiton. That is to say, it's doubtful that we would make it to the Playoffs at a large event.

I can't speak for the Greenhorns robot since I haven't seen it in action much, but I am nearly certain that the 'Snow Problem robot would be picked for the playoffs at any regional.

I am not trying to defend my team because I am insulted. Rather, I'd like to think I know the capabilities of an average team, and I am almost certain that the average team would not be able to produce something that can do as well as the Snow Problem robot.

[sviridovt]

It really depends on the robot stability, however just like someone said, tote score is linear, so higher stacks are a waste unless you have a can on top (and if you are going to put a can you might as well put a noodle in it.

[MrJohnston]

You can also stack a tote with a bin on top of it on top of 5 totes. Or two totes and a bin on top of four.

Yes, you can. However, that does not change the fact that, at the moment you are finishing the stack, nearly the entire bin is going to be above 6'6". Thus, the "challenge." You can certainly minimize that time (i.e. approaching a stack of 4 totes and placing 2 totes+ 1 bin on top). However, that bin will still be largely unsupported for a brief amount of time. Moreover, you now necessitate the creation of two separate stacks in order to build one tall one. This increases the amount of maneuvering the robot must do for each stack - increasing the amount of time it takes to make that stack.

I'm not saying either thought is a bad idea at all. I'm just saying that level six stacks with bins present some additional challenges that may make it more time-effective to max out at five.

[cadandcookies]

Yes, you can. However, that does not change the fact that, at the moment you are finishing the stack, nearly the entire bin is going to be above 6'6". Thus, the "challenge." You can certainly minimize that time (i.e. approaching a stack of 4 totes and placing 2 totes+ 1 bin on top). However, that bin will still be largely unsupported for a brief amount of time. Moreover, you now necessitate the creation of two separate stacks in order to build one tall one. This increases the amount of maneuvering the robot must do for each stack - increasing the amount of time it takes to make that stack.

I'm not saying either thought is a bad idea at all. I'm just saying that level six stacks with bins present some additional challenges that may make it more time-effective to max out at five.

I wasn't saying it didn't present extra challenges, just that there are ways to mitigate those challenges (that of course have tradeoffs of their own.

I'm going to bet that for most teams, it'll be easier to pick up a tote with a "standard" grip than a bin with 4" of grip. And it will probably be more stable as well with a bin properly placed.

In response to Caleb's comment: i think the build quality of the Snow Problem robot is probably middle to low tier, but the strategy is one that would make for an excelleny second or third pick, especially for teams that have the extra six weeks to "do it right" and improve the build quality.

[kachea716]

Summary, lift should be able to elevate an object 4.5ft. Allows you to stack a tote on top of 3 totes on the step and allows you to put a container on top of 4 totes if you are grabbing it by the lip.

It makes sense that you can get another tote on a 3 stack but you wouldn't be able to lift a container on top of a 4 stack of totes which is about 4feet tall, and if the lift only elevates the (about) two foot container 4.5ft. (grabbing it by the lip and not the bottom) it couldn't be stacked.

[Thatguyfrom716]

Stacking any number of totes takes time. If one were to stack 3 totes, you will be able to easily stack the container on top of them. If you were to make a stack of over 6 totes, it would waste a lot of time and you risk knocking the entire stack over.

[who716]

I wonder how much this poll will change at the end of builds season it would be interesting to see!!

[Munchskull]

The stack hight dilemma has four factors: the space the stacks take up, stability of the stack, if you have a container, and finally stack time vs unload time.

First off the most basic stack high vs stack out problem becomes, if I only stack out how soon will I run out of space to score totes. After a number of low stacks you will start running out of scoring space. Logic dictates to build up not out for this factor.

Next is the stack stability. The higher the stack the less stable. This seems to be the crux of this debate. I personally think that in this game mistakes will be made and robots will bump the stacks, if the stacks are tall then it endangers your stack more. So short stacks is prefered here.

Second to last we have, does the stack have a container on it. This is simple if yes then stack high, you have three containers for sure, so to make the most of the containers you should stack them high. They are your most limited resource in this game.

Finally we have the stack time vs unload time conundrum. If your robot can stack faster than it can unload then you would be better to stack high rather than short.this is because if you can get it in 6 totes and unload then it'll be faster than getting in 3 totes and unloading then repeating that process.

Time1= 6×totes+1×unload
Time2= 2 (3xtotez+1×unload)

Here the scores are bother the same but the extra unload instance takes time from scoring. In this case I think high stacks are better.

[AllenGregoryIV]

It makes sense that you can get another tote on a 3 stack but you wouldn't be able to lift a container on top of a 4 stack of totes which is about 4feet tall, and if the lift only elevates the (about) two foot container 4.5ft. (grabbing it by the lip and not the bottom) it couldn't be stacked.

You don't have to use the same attachment point to lift the totes and containers and the top of your lift won't only reach 4.5ft from the floor. I said be able to elevate an object 4.5ft. That means your lift or arm has 4.5ft of displacement. How you pick up the totes and containers and where they are attached to that lift or arm is up to you. We'll have a video up shortly of our prototype arm, it can do all things I said.

[jengl]

I think this question depends a lot on what kind of robot you plan on building. Do you plan on making a short, fast robot, or a bulky, large robot? Speed would make multiple stacks feasible, and as soon as multiple stacks become a possibility, it is my opinion that trying to balance 6 totes isn't worth the time it takes to stack them.