Engineering help?

[bam-bam]

I'd like to contribute more to the team next year, but before I do so, I feel I need to know what I'm messing around with in FRC. Are there any help with this?

What I'm looking for (but not limited to) is along the lines of:

• How do CIM works?
• What are encoders?
• What are commonly used motors in FRC? And
• How do they work (what is their function)?
• What are some necessary engineering terms I need to know (colson, casters, etc.)?
• What are some important formulas?

Generally, everything I need to know about designing a robot.

Thanks!

[MrForbes]

Originally Posted by bam-bam

Generally, everything I need to know about designing a robot.

Just read every technical thread here on CD...you'll learn all you need to know, but it might take you a while!

Seriously, you kind of need to learn one thing at a time. Like in school, you have detailed lessons about different things every day or every few days.

I'll start with motors. The CIM, like all the motors we use on FRC robots, is a permanent magnet, brushed motor. The CIM is the biggest, heaviest, most powerful one we've had for the past few years. Other motors include Fisher Price, BaneBots, AndyMark, and Mabushi, and various automotive power window motors. They're all PM brush motors, but some are designed for higher torque, some for higher speed, some are lighter, some have gearboxes included, etc.

To figure out what motor to use for a certain part of the robot, you have to figure out what is required. The main things are speed and torque. You can also look at speed and torque as how much electrical power the motor can turn into mechanical power. You'll find a Watt rating on the data sheet that lists the technical specifications for the motors

http://www.usfirst.org/sites/default...torInfo4.2.pdf

[jspatz1]

Holy cow, why didn't I think to ask for "everything I need to know about designing a robot" when I first started? Could have saved 6 years of trial and error.

[A_Reed]

Motors are rated by power and power is absolute.

You only get so much power out of a motor (W, hp) and through gearing you inversely trade off speed for torque. As you gear lower you gain torque and sacrifice speed. The general relationship is:

Power = Torque x Speed
(Apply appropriate units and conversions)

Another note to remember if you are interested in gearing for an FRC robot is that you are current limited. The CIM motors have the capacity to draw up to 133amps at stall (max torque, 0 rpm) but your power distribution to that motor is limited to 40 amps max. There is a white paper in CD-media somewhere that will explain the concept of a traction limited drive system based on the 40 amp max.

One of the bigger things that has helped me since I was a student in FRC is gathering a basic understanding of the mechanisms used in FRC. Take some time at your events and through these message boards to study the various mechanical devices some of these teams come up with and not only look at how they are used in this year's game but look at and learn how they function on a basic level so you can apply them to future scenarios.

One final note, wikipedia and howstuffworks are your friends. Most mechanisms can be broken down into something that is used in another industry and can typically be found somewhere on the internet with detailed sketches and little animations that assist the understanding process.

EDIT: Paul Copioli's White Paper on Drive System Design. http://www.chiefdelphi.com/media/papers/1378

[Anupam Goli]

A great resource is the White Paper section of Chief Delphi. You can learn a lot about the technical aspects of robots there

thinktank.wpi.edu is also a great source for presentations and papers on various topics relating to robots and engineering. This is the best place to start out. You'll find presentations by Andy Baker here which are keystones to success.