Robotics Question of the Day!

[1502]

Hi, All

We're looking for questions related to robotics that would start our meeting off. They can be related to pretty much anything as long as the average kid can answer with a bit of thought. We'd like a fun way to get the kids' minds going and would like to try it out. Also, if your team is doing this, how is it going? Feel free to use this idea if you'd like.

My example was, "How can decreasing a drivetrain's gear ratio increase its top speed?"

Post your questions below.

Thanks,
Ryan

[tsaksa]

Here are a few.

1. If FIRST changed the rules and allowed you the option of a second battery, would it be an advantage to use it, a disadvantage, or does it depend on the game, your strategy, etc. and how?

2. Each year there are robots with different drive mechanisms, but only a few types seem to be represented as a significant percentage in the finals. What is it that makes some of the different drive trains more or less competitive?

3. When building a robot you can choose different materials for the frame and other key parts such as aluminum or steel tubing, strut, sheet metal, wood, plastic, etc. How do the properties of these materials affect the choice and how many properties are there that are important in a decision on what to use?

4. Many teams are building T-shirt launchers to help promote their teams. If you wanted to build one, what design factors would you need to consider if you wanted to shoot T-shirts into high bleachers.

[sg999]

Here's one I used for discussion in an FLL team I mentor:

What would I have to do to a two wheeled vehicle to make it stable? (Make them think outside the box- I got some really interesting responses, some of which were practical and helpful)

[RyanCahoon]

Originally Posted by 1502

My example was, "How can decreasing a drivetrain's gear ratio increase its top speed?"

How can increasing a drivetrain's gear ratio increase its top speed?

[Nate Laverdure]

Originally Posted by 1502

My example was, "How can decreasing a drivetrain's gear ratio increase its top speed?"

Originally Posted by RyanCahoon

How can increasing a drivetrain's gear ratio increase its top speed?

Confusing to talk about increasing a ratio (e.g. 10:1) because it's unclear which quantity (1 or 10) you're increasing. Better to ask "How can decreasing a drivetrain's gear reduction increase its top speed?"

[1502]

Originally Posted by RyanCahoon

How can increasing a drivetrain's gear ratio increase its top speed?

When the gear ratio is too big for the wheel and motor combination. We experienced it this year. We put on a sprocket that was to small by accident and it would barely move. We doubled the diameter of the sprocket on the wheel and we were golden.

Thanks for the replies, and keep them coming!

[BJC]

How about:

What is the most important part of the robot?
A.The drivetrain

What is the second most important part of the robot?
A. Game piece pick-up

Have to keep these in mind come design time, its easy to only think about scoring..

Regards, Bryan

[CalTran]

If you are 100% sure you can score 2pts in the end game, but have the possibility (~50%-65% chance) of scoring 3pts if you skip the end game, which should you choose?

This was something that we had to ask ourselves back in 2010 nearing the end of season on debating whether to add the hanging mechanism.

[z_beeblebrox]

Originally Posted by CalTran

If you are 100% sure you can score 2pts in the end game, but have the possibility (~50%-65% chance) of scoring 3pts if you skip the end game, which should you choose?

This was something that we had to ask ourselves back in 2010 nearing the end of season on debating whether to add the hanging mechanism.

Depends on whether the extra point is needed to win.

[CalTran]

Also bear in mind, for discussion on cd, that 2010 was year of the horror ranking system. But for purposes of the op's post we can throw that out the window since rookies are highly unlikely to understand (I sure didn't) the system.

[RyanCahoon]

Originally Posted by Nate Laverdure

Confusing to talk about increasing a ratio (e.g. 10:1) because it's unclear which quantity (1 or 10) you're increasing. Better to ask "How can decreasing a drivetrain's gear reduction increase its top speed?"

I guess I think about it as increasing or decreasing the equivalent fraction (10/1 in the case of your example). Maybe I'm wrong...

Originally Posted by 1502

When the gear ratio is too big for the wheel and motor combination. We experienced it this year. We put on a sprocket that was to small by accident and it would barely move. We doubled the diameter of the sprocket on the wheel and we were golden.

Right, I was pointing out that both are valid questions.

According to the Wikipedia definition at least, gear ratio is the ratio of the input speed to the output speed, so putting a larger sprocket on the wheel (or conversely, a smaller sprocket on the driving axle) would increase the gear ratio, creating a greater speed reduction. This reduces the theoretical unloaded freespeed, but, as I believe you're saying, can increase the top speed in torque-starved conditions.


Some other questions:
- Why is it important to keep electrical wires as short as possible? (Signal wiring and power wiring can have different answers, though there is overlap)
- What would be some advantages/disadvantages of using a smaller amount of a stronger but heavier material vs a larger amount of a weaker but lighter material (e.g. steel vs aluminum)

[JVN]

Originally Posted by BJC

What is the second most important part of the robot?
A. Game piece pick-up

Incorrect. A much smarter man taught me that the second most important part of the robot is... the drivetrain.

Do you want to know the third?

[Tottanka]

Originally Posted by JVN

Incorrect. A much smarter man taught me that the second most important part of the robot is... the drivetrain.

Do you want to know the third?

Drivetrain. Mr. Beast.

[MARS_James]

For rookies our first question of the day is

What does FIRST stand for?
If you can't get that down no point in asking them mechanical questions because they aren't getting FIRST

Some team specific questions are also always good:
What year did we start?
What was our first game?
etc.

I always also enjoyed this question:
How do Mecanum wheels work?

[Alan Anderson]

Originally Posted by BJC

What is the most important part of the robot?
A.The drivetrain

What is the second most important part of the robot?
A. Game piece pick-up

No, the second most important part of the robot is also the drivetrain.

So is the third.

Game piece manipulation is no higher than fourth on the list of robot priorities.