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Unread 28-04-2013, 02:01
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Re: How to make your robot withstand the beating

Our chassis survived the year pretty much unscathed. We machined ours out of tube aluminum stock (which can be found on McMaster & local aluminum retailers). This provided rigidity, along with a place to safely put 2 Clippard Air Tanks & our drive train modules.
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Unread 28-04-2013, 03:56
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Re: How to make your robot withstand the beating

Build and experiment with different types of chassis and drive types (omni drive, swerve drive, tank drive, 6 wheeled etc...) and work out the problems that arise then when you got the time to fix them rather then during the build season. That way when you go to build the real one for that seasons robot you know how to assemble it. Usually it's pretty similar each year so you get good at it after a while. Summer is also a good time to use CAD programs to stress analyze where there are weaknesses so you can strengthen it up. Also, think triangles they are strong. Knowing when to use which type of nut and not leaving them laying around on the robot, it'll save you the panic later when one falls out and you don't know where it went. Cover Victors and Jaguars when working on robot, or use Talons, they can be a pain when they stop working and you have to take crucial time troubleshooting. Build simple east to fix mechanisms. This year not one thing broke on our robot because it was a simple dumper with 2 sides to hang, but still effective.
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Last edited by BrianArneson : 28-04-2013 at 23:05.
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Unread 28-04-2013, 09:21
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Re: How to make your robot withstand the beating

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Originally Posted by runneals View Post
Our chassis survived the year pretty much unscathed. We machined ours out of tube aluminum stock (which can be found on McMaster & local aluminum retailers). This provided rigidity, along with a place to safely put 2 Clippard Air Tanks & our drive train modules.
That butterfly drive is almost identical to our octocanum setup. Out of curiosity, what did you use for the traction wheel?
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Unread 28-04-2013, 12:09
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Re: How to make your robot withstand the beating

Our team always uses welded aluminum frames with very sturdy bumpers. These are great if you get into any collisions. We had several collisions during the course of the competition season that left us completely unscathed and other robots bent out of shape.
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Unread 28-04-2013, 12:35
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Re: How to make your robot withstand the beating

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Originally Posted by pfreivald View Post
That butterfly drive is almost identical to our octocanum setup. Out of curiosity, what did you use for the traction wheel?
We put rough top on our custom designed traction wheel. It worked really well for us (and the other teams who chose to use it as well.
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Unread 28-04-2013, 12:55
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Re: How to make your robot withstand the beating

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Originally Posted by runneals View Post
We put rough top on our custom designed traction wheel. It worked really well for us (and the other teams who chose to use it as well.
Thanks. We tried Colsons on our traction wheels, and were less than satisfied with their performance on carpet. (Alas, last year we had rough top on our traction wheels, and loved them on carpet but were less than satisfied on polycarbonate!)
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Unread 28-04-2013, 19:38
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Re: How to make your robot withstand the beating

Build within your means – not every team has machinists, welders, and the like with the capability to make parts, chassis, and manipulators with skill. Know your limits.

I'm going to echo others on this thread. Past failures are the best teachers.

Specifically, consider adding redundancy to the robot. Try to avoid designing in possible failures that would affect multiple subsystems on the robot. From a reliability standpoint, consider west coast drive.

Team 20 chose a six-wheel, dropped center west coast drive this year, saving us in WPI, during Finals 3. In our case, it let us continue to drive – absolutely necessary for our floor pickup and shooter. This design choice helped us to remain operable, though not at our best.

After seeing Einstein, I am definitely willing to put a zip tie around the Anderson connectors to the PD Board and the battery...
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Unread 28-04-2013, 20:02
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Re: How to make your robot withstand the beating

Keep your mechanisms simple, with fewer parts to break.
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Unread 28-04-2013, 20:20
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Re: How to make your robot withstand the beating

Don't make it out of wood.

There goes our passive climber. #woodenrobotproblems

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Unread 29-04-2013, 18:22
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Re: How to make your robot withstand the beating

Quote:
Originally Posted by brennonbrimhall View Post
From a reliability standpoint, consider west coast drive.
Seconded, with a couple of caveats.
1. - The same WCD wheel block design will get positive and negative comments from people here on CD. There doesn't seem to be one "best" design because they're all subject to the precision a team can get with manufacturing.
2. - The best way to know the best practices on WCD is to build it early. We did that, and it helped reliability a lot during the build season. We'll change the wheels, maybe use belts, and tweak the design of the blocks -- but I don't know that we'll ever move away from WCD now.
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Unread 29-04-2013, 19:11
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Re: How to make your robot withstand the beating

Our drive was not a WCD, but it was similar, only with a 1/4" plate on the outside and a 3/16" plate on the inside (or vice versa, not quite sure) and wheels in the middle. Direct driven wheel in the middle and dead axle chain driven wheels front and back made it super easy to work on the drive with no box fram, which was the original plan, one used previously. Although by the end of the season we had a small warp issue, the drive ran fine and we played some really intense,aggressive defense, so the forces on the drive were ridiculous.

My advice, do CAD testing and build it pre-season, in order to save immense amounts of time later. Design is iterative, so building and beating the crap out of it, then fixing the weak points, and repeating, is the best way to improve robot strength, and you will learn a lot about strong design in the process.

Also, if your team has limited funds, try a Kitbot on Steroids from Team 1114, Simbotics, as it is a great, rock solid drivetrain that works.
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Unread 29-04-2013, 19:43
Kevin Leonard Kevin Leonard is offline
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Re: How to make your robot withstand the beating

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Originally Posted by pmangels17 View Post
Also, if your team has limited funds, try a Kitbot on Steroids from Team 1114, Simbotics, as it is a great, rock solid drivetrain that works.
Simbotics isn't a Hall of Fame team for nothing. The resources they make available to the FIRST community are extremely useful for inexperienced (and some experienced) teams.


Quote:
Originally Posted by brennonbrimhall View Post
Specifically, consider adding redundancy to the robot. Try to avoid designing in possible failures that would affect multiple subsystems on the robot. From a reliability standpoint, consider west coast drive.

Team 20 chose a six-wheel, dropped center west coast drive this year, saving us in WPI, during Finals 3. In our case, it let us continue to drive – absolutely necessary for our floor pickup and shooter. This design choice helped us to remain operable, though not at our best.

After seeing Einstein, I am definitely willing to put a zip tie around the Anderson connectors to the PD Board and the battery...
Now while West Coast Drive is great, and it worked extremely well for our team this year, it's not always the most viable option, especially for teams inexperienced with WCD and drive trains in general.
In considering different drive trains- build some in the offseason, see which are the easiest to build, design, program, tune, and test. Compare their weights and attributes. I've seen far too many teams use Mecanum this year that had no good reason for doing so other than they thought it was cool.

As for building a sturdy robot, my recommendation is to keep your main systems lightweight, then add reinforcement. If you look at Team 20's robot this year, everything is reinforced with brackets and C-Channel. to prevent damage.
We only broke twice during the season. Once during WPI finals, when our drive train's chain broke (as Brennon said above, we could still drive and score), and once at CMP when the cylinder that raised and lowered our shooter tray bent after a big collision with Team 4265 (Awesome team, btw. One of the best robots in Archimedes- and they were a 2nd year team!).
In both instances, we could still drive, score points, and collect, just not quite as well.

Robustness and reliability are just as (if not more) important than the amount of points you put up. If you're the best robot Day 1 of competition: That's great!
But you need to be able to repeat your performance Day 2- especially since the Defense gets even tougher.
Good luck with your season!
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