How much planning goes into your robot?

[Jnadke]

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.