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View Poll Results: How much planning goes into your robot?
Drafting - None or very little pre-assembly planning - Hey, We're Optimistic. 27 12.39%
Drafting - Moderate - Only essential systems are drawn up. 94 43.12%
Drafting - Extreme - You could drive the robot before it's been built! 73 33.49%
Calculations - None or very little - We live on the edge. 18 8.26%
Calculations - Moderate - Yeah, we did a few to get some things right. 107 49.08%
Calculations - Extreme - Is that an African or European Swallow? 59 27.06%
Robot!?!? You mean we're supposed to be building a robot!? 30 13.76%
Multiple Choice Poll. Voters: 218. You may not vote on this poll

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Unread 05-09-2003, 06:34 PM
Jnadke Jnadke is offline
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How much planning goes into your robot?

I was thinking about how many factors can affect the performance of a robot in another thread, and I began to wonder how much planning other teams actually do in the creation of the robot. By planning I actually mean two categories: Calculations and Drafting.

Drafting: Whether it be hand-drawn or computer-aided, accuracy is key in creating a robot that operates efficiently. How many teams just "wing it" and do barely any drawings? How many teams only draft key features such as drive components? How many teams draw their entire robot up before a single component is built?

If you just draw pictures of your robot without any specific numbers to them, you'd fall under "No Drawings". Drafting involves dimensions. Every team most likely draws pictures of how their robot should look.

Bottom Line: Say if your robot spontaneously blew up at regionals (Hey - It could happen). If you could send the CAD drawing to a professional machine shop, and they could build your robot (before any "tweaking") without you telling them a thing, then it's extreme.



Calculations: A lot of equations fall into the design of a robot. Not matter what, you will use them. However, how many of them you use is up to you. How many teams calculate very little (teams that used FIRSTs stock drivetrain would most likely fall here) and just wing it based on personal knowledge? How many teams factor a moderate amount of calculations in designing their robot? How many teams have done extensive calculations in their robot design?

For example, if you are creating a shifting robot and you want, on a low end, a high-torque robot, and, on a high end, the fastest robot you can get without tripping breakers, what do you gear the high speed to? Well, if we look at the breaker spec sheets, you can draw 4 times the rated current for 1 second before they trip. You can draw 2 times the rated current for 5-8 seconds before they trip. Now, if you're pessimistic, and you say your robot is 70kg (~140lb), you can calculate how long it will take your robot to accelerate using the equation:
Torque = (Moment of Inertia) * (Angular Acceleration)
where
Moment of Inertia = robot weight * (overall gear ratio * motor shaft radius)^2
Now, you can generally say that current consumption for a torque at 120A should decrease to 80A within 1 second, and that the torque for 80A to 40A should decrease within 5 seconds. I've skipped a lot of steps here, but eventually you'll end up with a differential equation that's equal to the minimum gear ratio you could use.

I would consider this the "extensive calculations" category. I guess this goes hand-in-hand with robot complexity. A standard drivetrain doesn't require very many. All you need to do is decide whether you want high-torque or high-speed and qualitatively analyze the motor-torque curve. Then just pick out a good gear ratio.

Bottom Line: If your calculations could be performed (or were) by a standard high school Physics student, then you'd fall under the moderate category (High School level math). If your calculations required special knowledge in Calculus (such as my example), Materials Science, Thermodynamics, Electrical Engineering (College-Level Stuff), then I'd consider it extreme.

Check all that apply. If you weren't responsible for designing AND/OR you weren't responsible for calculations, please don't vote (or vote for #7) so you don't mess up the results.


As for my old team, 93, we had a rule that "everything must be drafted before it is built". On the calculations side of things, we'd fall under "moderate". Overall, the gear ratio was done right, according to current constraints, but not to the level of optimizations in my example.
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Unread 05-09-2003, 07:25 PM
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TechnoKats 45

If I could have voted for two items it would have definetly have been extreme for both of them. Andy Baker (who is the MAN at doing CAD) draws everything in UG and prints it off to be made. You may have even seen our print book at some of the events in previous years. Another cool thing that Andy does is print off full scale or 1/2 scale prints of assemblies on the robot. I can remember in 2002 when we had an full size print of the drive base and I used it to align the gearboxes. For calculations I'de also have to say we are extreme. Everyone is always doing calculations, and there are 3 engineers on our team that do an extreme amount of it (Andy, Mark, Steve).
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Unread 05-10-2003, 10:02 AM
Gadget470 Gadget470 is offline
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I did post-production drafting of the entire robot (as it was being built). We didn't have any CAD models to work off, we had hand sketches. Being that we used extruded aluminum, we safeguarded just about everything by making sure it's function could be slid a few inches an whatever direction to work right. Our only problem? Our Tape Measure said 36".. FIRST's said "36 1/4".. Answer: Portable bandsaw.

Calculations were done mostly for our gearbox and finding a desired Torque vs Speed since we did not shift gears. Past that, finding the correct point to mount our pnuematics for our 15lb downward dropping wings to fall to a horizontal and still be able to come back up.
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Unread 05-10-2003, 10:26 AM
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This is an interesting thread, because i have the same questions. I know that many teams do very little drawings, and I have noticed that sometimes there success rate is lower then the teams that do many drawings and calculations. I have also seen that if you spend to much times on calculations you sometimes do not have enough time to get the robot done. There was a team that i met at the national event that had a very well desiged plan, but when they tried to implement the plan, it did not wuite work the way they wanted it to. It turned out that at this teams first regional they did rather poorly, and made many changes before the second regional event. In the end they were a low rider, which everyone knows was an important factor in this game this year. I believe that sometimes teams need to look at the big picture before they build. I also think that brainstorming is important. FIRST wants you to figure out how to play the game, and how to play it more effectivly then the other teams. I always say that the more ideas you have the more effective you're chances of winning are. I hope to see you all again next year.
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Unread 05-10-2003, 12:28 PM
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Our level of detail depends largely on the criticallity of the system.

We did do calculations to determine the gear ratios for the drive, but didn't do extremely detailed drawings of the skyway wheels or the drive sprockets. These items were roughed in on the overall assembly, but we didn't figure out exactly where everything was going before starting to build. There were "keep out" zones on our overall assebly drawing to cover this. Besides you don't want anything important in the drive bay near the chain anyway. To much risk it will get damaged by the chain if something bad happens.

On the other hand, our ramp gripping arms were completely modeled, including the motion, before we built anything. In fact we used the CAD drawings as patterns for the linkage parts when we built them. Our box gripper and lifting arm were also modeled and checked using FEA before being built.

Our drive motor mounts and the gearbox for our arm were mostly done in CAD before we built them. I say mostly because Rick Varnum, our machinist, (who is probably lurking out there somewhere) decided we needed to lighten up the sides of the gear box so he used a CAM program to generate an NC program for that. It took less time than adding the pockets in Inventor. Besides the pockets were not critical to the function of the gearbox or any mating features.

On the other hand, our "light lifter" which kept our light from being bashed on the bar, was built on-the-fly and never has been documented.

Over all, I think we did more layout and planning this year than ever before. We also placed higher than ever before.

A coincidence?
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Unread 05-10-2003, 12:33 PM
Jnadke Jnadke is offline
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Quote:
Originally posted by Gadget470
I did post-production drafting of the entire robot (as it was being built). We didn't have any CAD models to work off, we had hand sketches. Being that we used extruded aluminum, we safeguarded just about everything by making sure it's function could be slid a few inches an whatever direction to work right. Our only problem? Our Tape Measure said 36".. FIRST's said "36 1/4".. Answer: Portable bandsaw.

Calculations were done mostly for our gearbox and finding a desired Torque vs Speed since we did not shift gears. Past that, finding the correct point to mount our pnuematics for our 15lb downward dropping wings to fall to a horizontal and still be able to come back up.

Hand Sketches are still considered drafting if they have numbers on them. Just as long as you include dimensions of how long a part is supposed to be, it doesn't matter how it looks freehand. If you have a circle cut out of an aluminum plate, you should have the length, width, distance of the circle center from the corner (x,y), and the radius of the circle. If you had those 4 things, a machine shop could replicate that part. I'd consider that extreme, but only if the entire robot was drawn up.
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Unread 05-10-2003, 09:40 PM
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I think that every tobot needs some planning. I really don't think it would even be possible without some planning. There are so many parts of a robot, and the drive train must be carefully planned before construction can begin. I have gotten the chance to talk to a lot of rookie teams this year, and many of them plan more then even championship teams do.

Good Luck to everyone this year at the invatationals. See you guys next year.
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Unread 05-11-2003, 01:30 AM
Gadget470 Gadget470 is offline
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Well of course everyone has some planning.. nobody just starts building without telling others what is about to be cut and why with reasons.

Some teams just don't have the resources to make CAD/Inventor mockups of parts in the time needed. Sometimes a little trial and error can be faster than Calculate, Dimension, ReCalculate, Assemble.
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Unread 05-11-2003, 08:35 AM
Jnadke Jnadke is offline
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Now, a question for the teams who voted extreme:

If you voted extreme for drafting, why did you feel the need to create accurate drawings of all robot components? Did it make the build process easier?

If you voted extreme for calculations, what did you use the equations on/from? If you voted here because of a custom circuit, no need to answer (although you're in the correct category).


I'm trying to get a survey of how competitive it has become. In general it seems that teams are sticking to High School level stuff. I'd venture that a few teams would fall under extreme for both categories, such as 45 and 111, who may have used differential equations in calculating gear ratios, or used special knowledge to create a custom circuit.
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Unread 05-12-2003, 11:15 AM
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We spent two weeks brainstorming and cadding our ideas. We made every nut and bolt on the robot and had everything just as it would be on the bot. It helped oh so much when we had to send out parts to be made b/c the ppl could look at the sketch and know what they were doing. It may be tedious work, but it is definitely worth it to spend the time making every part--it saves a lot of time and chaos in the end. We even had our bot finished like five days BEFORE we shipped this year!! That never happens. We were able to practice with it, which definitely helped.
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Unread 01-27-2004, 07:44 PM
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Re: How much planning goes into your robot?

I'd Assume a lot of planning goes into every teams robot. Its kind of like the famous saying...measure twice cut once. You've got to go over and over on everything to make sure you're on the right track, then you put all your ideas into the actualy building of the bot.
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Unread 01-27-2004, 08:02 PM
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Re: How much planning goes into your robot?

We don't usually spend a lot of time drafting, but we model with cardboard. After the robot is built with cardboard, we draw up dimesioned drawings and go from there.
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Unread 01-27-2004, 08:40 PM
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Re: How much planning goes into your robot?

We CADed the frame, the Gearboxes, and I have at least 30 pages of notes(typed, CADed, written, or scribbled) detailing our autonomous system. We did calculations for the drivetrain, and manipulators. Everythign has at least a sketch. There are probably manipulator CAD drawings, but that's not really my part of the robot. I guess our team would fall under moderate calculations, and moderate draftings category. We don't have a cad model down to the last bolt of our robot, but we are doing ok.
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Unread 01-27-2004, 09:31 PM
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Re: How much planning goes into your robot?

Our team in the past has had sketches and ideas, with a FEW drawing with numbers that disapeared somewhere after the design decision making was over with. This year, we handled things a bit different, making cardboard models of the robot, and I've been marking everythign about the drive train out on paper, running whatever math I can (trig) and using a pencil and calculator like a madman making sure everything works and all that.
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Unread 08-11-2004, 10:16 PM
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Re: How much planning goes into your robot?

Planning?!! Boy our team went from one end of the spectrum to the other from 03 to 04. in 03, every piece of our bot was drafted before it was built. In 04, we were working off napkin sketches and our imaginations. If something dont work right you redo it. As for calculations, we did some but they went largely ignored until we found out we had problems. The main problem there was switching from drill motors with stock gearbox to chippewa motors with no gearbox. wild guesses don't cover that very well
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