Team 1114 - Simbot SideSwipe

[Darkseer54]

Is there any reason that you decided to use banebot wheels over the blue urethane wheels on the final robot?

[akoscielski3]

Originally Posted by Darkseer54

Is there any reason that you decided to use banebot wheels over the blue urethane wheels on the final robot?

We used many different wheels while prototyping. With the Banebot wheels we were able to intake almost any tote, in any orientation. We even had it picking up a tote that was almost completely sideways (from what our normal orientation for totes was). The only downside was that the orange rubber would wear out pretty quickly. I believe we ended up changing them almost everyday during competition.

The blue wheels were not as effective, however they did not wear out as quickly. They were still pretty good though. We used the blue urethane wheels on our practice bot because they didn't wear out, and we wouldn't have to change them. It also made our driver try and drive with intakes that weren't as good as the competition ones, making him struggle a bit and make sure he lined up with the totes properly.

For our team we will use what ever the best option is, no matter what colour it is, or if it takes a little more work to maintain the robot.

[NWChen]

Originally Posted by Karthik

Here's the video of our initial intake prototype. You'll notice the rudimentary nature of the setup; it's built with cupboard doors, old intake wheels, hand drills, and two old four caster carts.

https://youtu.be/jH4n1X1Oz7c

Very cool. Were there other approaches to intaking before this prototype? Any chance of more videos being uploaded?

[Karthik]

Originally Posted by Darkseer54

Is there any reason that you decided to use banebot wheels over the blue urethane wheels on the final robot?

In addition to the reasons that Aaron mentioned, the Banebot wheels were considerably lighter than the blue urethane wheels.

[Darkseer54]

Originally Posted by akoscielski3

We used many different wheels while prototyping. With the Banebot wheels we were able to intake almost any tote, in any orientation. We even had it picking up a tote that was almost completely sideways (from what our normal orientation for totes was). The only downside was that the orange rubber would wear out pretty quickly. I believe we ended up changing them almost everyday during competition..

Any reason as to why the banebot wheels were able to pick them up better? Did they just have better traction, or was there too much compression on the urethane wheels? Was it some other factor?

EDIT: I've been informed it was most likely the difference in durometer.

[Chris is me]

Originally Posted by Darkseer54

Any reason as to why the banebot wheels were able to pick them up better? Did they just have better traction, or was there too much compression on the urethane wheels? Was it some other factor?

EDIT: I've been informed it was most likely the difference in durameter.

disclaimer: i'm not 1114, i just played with intakes for six weeks

The Banebot polyurethane rubber seems like a very different material than the blue McMaster wheels. The consistency is closer to that of a pencil eraser than of a smooth rubber like the blue McMaster wheels, and the BB wheels will start to fail before they break traction with a game piece. The McMaster wheels are more durable so they'll slip before they fail, and they also seem subjectively a bit less sticky.

Durometer isn't an absolute measure of traction by any means. You can get the McMaster wheels in a durometer lower than the orange Banebot wheels. So I would not take a durometer number as gospel in terms of tractive force applied to a game piece - especially if you are comparing two different rubbers.

Another variable this year is that the amount of compliance your intake had affected what wheels worked optimally. 1114's intake was mostly rigid with a small degree of compliance in the outermost wheels for picking up cans. More compliant intakes seemed to prefer the blue McMaster or even the harder blue BaneBot wheels over the orange BaneBots (I was really surprised to see that the harder BB wheel would grip a tote better...). Intake design this year was definitely not something you could afford to guess on without prototyping extensively.

[mman1506]

Originally Posted by Chris is me

disclaimer: i'm not 1114, i just played with intakes for six weeks

The Banebot polyurethane rubber seems like a very different material than the blue McMaster wheels. The consistency is closer to that of a pencil eraser than of a smooth rubber like the blue McMaster wheels, and the BB wheels will start to fail before they break traction with a game piece. The McMaster wheels are more durable so they'll slip before they fail, and they also seem subjectively a bit less sticky.

Durometer isn't an absolute measure of traction by any means. You can get the McMaster wheels in a durometer lower than the orange Banebot wheels. So I would not take a durometer number as gospel in terms of tractive force applied to a game piece - especially if you are comparing two different rubbers.

Another variable this year is that the amount of compliance your intake had affected what wheels worked optimally. 1114's intake was mostly rigid with a small degree of compliance in the outermost wheels for picking up cans. More compliant intakes seemed to prefer the blue McMaster or even the harder blue BaneBot wheels over the orange BaneBots (I was really surprised to see that the harder BB wheel would grip a tote better...). Intake design this year was definitely not something you could afford to guess on without prototyping extensively.

For comparison we found our custom 30A durometer urethane wheels to have about the same or slightly better traction than orange banebot wheels. The BB wheels are aerated rubber not urethane.

[Bryce2471]

Originally Posted by NWChen

Very cool. Were there other approaches to intaking before this prototype? Any chance of more videos being uploaded?

I am also interested to hear the answer to these questions.

[Karthik]

Originally Posted by NWChen

Very cool. Were there other approaches to intaking before this prototype? Any chance of more videos being uploaded?

No, this was the first approach that any real effort was put into. There were many subsequent prototypes with different wheel spacing, wheel sizes, wheel types, tension in the surgical tubing, etc.

[JesseK]

Originally Posted by Karthik

No, this was the first approach that any real effort was put into. There were many subsequent prototypes with different wheel spacing, wheel sizes, wheel types, tension in the surgical tubing, etc.

The big lesson that carries from this year to the next is that there must be an active intake, and if the game piece doesn't conform to it then the intake must conform to the game piece. Having that design paradigm on day 1 would have set us up a bit better this year. I'm really impressed you guys had such a successful prototype on Day 3.

[Bryce2471]

Originally Posted by Karthik

No, this was the first approach that any real effort was put into. There were many subsequent prototypes with different wheel spacing, wheel sizes, wheel types, tension in the surgical tubing, etc.

If you don't mine me asking, how did you come to the conclusion that this would be the best intake to test, when you hadn't even made any previous prototypes? What was the thought process that lead to this unconventional intake geometry being your first attempt? Did you lay out the performance goals for the intake before hand? If so, what were they?

I am sorry if these questions come off to pushy. I'm just really interested in how you came to such an effective prototype so early.

Thanks again for all the information and resources that have been posted already.

[akoscielski3]

Originally Posted by Bryce2471

If you don't mine me asking, how did you come to the conclusion that this would be the best intake to test, when you hadn't even made any previous prototypes? What was the thought process that lead to this unconventional intake geometry being your first attempt? Did you lay out the performance goals for the intake before hand? If so, what were they?

I am sorry if these questions come off to pushy. I'm just really interested in how you came to such an effective prototype so early.

Thanks again for all the information and resources that have been posted already.

The thing was, this intake wasn't unconventional to a lot of us. We were expecting a lot more teams with this exact same style of intake in the season. I was surprised to see a lot less teams(or none) come up with this design (until later in the season).

The goals for the intake were:
- Fast at puling in a tote
- reorientate almost any tote, no matter what position it is in (besides up side down totes)
- Hold the tote inside our robot long enough for the indexer to pick up the tote
- Intake Cans, and upright cans

To accomplish these goals we thought that the intakes must somehow be able to pull the totes in towards us to orientate them, the wheels alone will probably not do this (We proved this later by removing the front wheels on this prototype). To pull the tote in you would need to have some sort of elastic pulling force to rotate it. THis is why we thought of the pivoting wheels on the outside. Also to make the totes go into the same position inside of our robot every time we would need to have another set of wheels that are "Fixed" (they actually can move a bit). So after coming up with the idea on the weekend, the students ran with it on Monday and came up with the prototype you can see above.

It worked pretty well at first, but we kept playing with spacing, wheels, elastic force and many other variables that we would think could affect them. After finding out the optimal things we began to CAD them, and they are now what you can see on the robot.

A few days later after the prototype we noticed that it might be possible to upright the Cans with out intake too. To accomplish this we tried adding something to make the can pivot around. Originally this was a just a 2x4 piece of wood someone would step on. We played around to find out if this was possible, and what the approximate distance from the inner wheels, this pivot would need to be. After building the robot the "Boot" as we called it, did not exactly perform as we hoped. During week one of competition (we were not competing) one of the members sketched up a rounded "boot" that would make a better pivot point, and guide the can upright. There is a picture of this in the Engineering Notebook on our website. Also to do this our intake would have to be spaced an extra 2 inches apart, which is why they have Cylinders on them to rotate inward and outward. These cylinders is why the inner "Fixed" wheels are not exactly fixed, they can be pushed outward a bit, but will move the tote back into the center of our robot when we intake it

Also you NEVER need to apologize for asking questions. Asking questions is how you learn. I would not be working on robots for a job, working on completing my Mechanical Engineering Degree and Diploma, and be a mentor on Simbotics if I never asked questions. At one point I was an eager and excited high school student who wondered all of these things too.

Ask questions, ask a lot of questions.

I hope all of this helps, and I wish you and your team a good luck in this upcoming season

[Gregor]

Originally Posted by akoscielski3

At one point I was an eager and excited high school student who wondered all of these things too.

Can confirm.

[JesseK]

That latch! Wow! How hard was it to balance the push-up force from below versus the cylinder's resistance, only to need to use the retraction stroke to then lift the entire stack in order to set it down? Was this accomplished via specific prototyping, calculations, a bit of both?

I also see an axle linking the front/rear latches on either side. Were there any issues with the left/right sets not firing at the same time, and if so what eventually solved it?

What are the 2 pieces hanging off the bottom of the claw for?

The long skinny horizontal cylinders that run front-back didn't seem to import correctly. Are they for pushing the tote stack out of the bot?

There are some really great nuggets of wisdom in the details of this CAD - from the nifty sheet metal carriage all the way down to the idler sprocket assembly design. I dunno how I would approach a rear-leaning tower without sheet metal though. It's a really neat design.

[Mike Marandola]

Originally Posted by JesseK

What are the 2 pieces hanging off the bottom of the claw for?

They for capturing the top of the stack. This picture shows it well:

Originally Posted by akoscielski3

Ask questions, ask a lot of questions.

I was given one of your worn out BB wheels at IRI and it's broached for 3/4" with a hex sleeve put in it. Why is that? Was it not originally 1/2" hex, did the plastic start rounding, or something else?