Howdy all,

Great job students and mentors on making major decisions, concepts, and models. Now it is time to AMP! it up. I hope to see everyone (students) this weekend. Remember there are no holidays for FIRST Robotics build season. On manuverablitity of the chassis a video is worth millions. I would really like to a ball go 21.4 feet on video.

I know that all of you are budding mathematicians, and that you are also really excited (as I am) about the robot. So this entry will probably be all review for you... Or not!

I was wondering what the relationship is between the size of the turret wheel, it's RPM and the angle of ball departure. Yes, this is the type of thing that keeps me awake at night. This, and coming up with the next clue. But more on that later! I am sure that all of you know that shooting the ball at a 45 degree angle results in the maximum range. This is, of course, neglecting wind resistance. So we now have one less variable to deal with. What is the rest of the math? I thought you'd never ask!

Step 1: The rim velocity of the turret wheel. Easy. Take the diameter times Pi times the RPM.

Step 2: the velocity of the Moon rock. Also easy. The rock moves at 1/2 the rim velocity. This is because it is basically rolling against a fixed surface. Let's also divide by 60 to convert to inches per second. So now we have:

Vball= Dia*RPM*3.14/120

Step 3: To determine the range we have to break the ball trajectory into two seperate components: It's vertical velocity (Vv) and it's horizontal velocity (Vh). Since we have assumed a 45 degree launch angle Vv and Vh are equal. Make a different launch angle assumption and you could apply that as well. But for now we'll stick to 45 degrees. If you draw a triangle with the moon rock velocity on the hypotenuse and the Vv and Vh on the other legs of the right triangle you can easily see that:

Vh=Vv=Vmoonrock/squareroot of 2=Vmoonrock/1.414, or if we do the neccessary substitutions:

Vh=Vv=Dia*RPM*3.14/120*SQRT(2) which is Dia*RPM/54 units inches/sec

Step 4: We now can determine how long the moonrock will be in the air. When something goes vertical at a certain velocity it begins to decelerate due to gravity. Then it comes back down. (Yes, we're ignoring really high velocities that can escape Earth's gravity. While our robot will no doubt have such power, we'll get kicked out if we use it!) The equation governing going up and going down is simple:

V=a*t, where a is the gravitational constant of 32ft/sec^2, because we are not really on the moon.

If we solve for t, with our initial Vh for V, we will now know how long the moonrock will go up before it comes to a stop in mid-air. Since what goes up must come down we need to double t to find out how long the moonrock is actually in the air. Please note that I am assuming the turret height to be approximately the same as the trailer height. This is a good assumption for reasons I can explain tomorrow. So how long is the moonrock in the air? If I multiply all the constants and convert 32ft/sec^2 to inches, the simplified formula is:

Ttotal=Dia*RPM/10370 seconds. Wow.

Step 5: How far does the moonrock go horizontally in this time? After all, this is the range! We already know the horizontal component of the moonrock's initial velocity, Vh, and only need to multiply this by the time the moonrock is in the air to find out our range.

Range = Ttotal*Vh, or

Range = Dia^2*RPM^2/559978 inches.

How about some real numbers? Let's try a 4" turret wheel at 3000RPM. And let's divide the result by 12 to get feet.

Range = 4*4*3000*3000/559978*12 = 21.4 feet!

There you go! Oh, the clue? Simple: 21.4 feet!

See you tomorrow!
Dean

We looked up different wheel bearings. Sherwood found a chassis that had movable bearings that could allow us to tighten the chain by loosening the screws and moving it to the correct position and tightening it back up. We made a design matrix and figured that the old chassis is the way to go. We will draw it up and find out how much material is needed hopefully by next time.

This design consists of a passage that will take the ball up and dump it in the hopper, top feeder, then the hopper will funnel into the ball loader. The ball loader will have the turret on top to shoot the balls with aim. Topics of discussion are a bottom feeder and using just one passage for the ball to travel through instead of 2. Hopper will hold 16ish balls.

Thanks for the post last night, Ian. Are we going to have a link to Daniel's video on the blog? I'm sure the team would like to see how effective the system was.

Another clue: If a picture is worth a thousand words, a video must be worth millions!

Electrical team: We need to get encoders on the KOP chassis for the programming team to start using. We also need to start planning the panel, which means we need to know the number of Jaguars, Victors and Spikes. Maybe we can spend some time on that tonight.

See you all tonight!

Dean

Today we prototyped what we wanted to be the shooting mechanism using wood, conveyer belts, pulleys, and a screwdriver. The conveyer belts worked best with teeth out. The Plastic tubing slipped off the pulley quite a bit but tension wasn't the greatest.
The foam wheels at the bottom worked well to help grip the ball to pull it into the system. The system also worked well shooting the balls out of the bottom of the system.

Video of the ball feed prototype

Last night the programing team worked on the color recognition code so we can tell the two alliances apart in autonomous mode. We also talked a little on strategy in autonomous mode. And we did some boolean math (Arg I said the M word). But most of the time we were testing and debugging testing and debugging... the camera code.

And in other news I've got the story board down and started building bricks today for the and if you went hear the day I said what I was doing for that I can tell you what I'm doing now. The challenge for this year is bio-mimicry (taking something from nature and replicating its affect into a man made device). And I'm going to do the whole thing in CG LEGO animation to see what those are click the this link www.bricks3d.com .

Happy bloging

Today we sorted the parts from past robots in order to be able to build robot in an organised fashion

the mechanical team decided on a robot that suced the balls up from the ground, store them in a hopper with a conveyer in it to move the balls to a two conveyer vertical shooter that ends in a 360 degree aiming device.

MECHANICAL BLOG
We listed the pros. and cons. for many different types of each and as a group came up with these final decisions. We also watched a couple videos on different driving systems.
Final decision for drive system is Tank Drive.
Final decision for ball manipulation is single pipe.
Our chassis will be wider in the front (38" and sides will be 28".
The ideas for the ball manipulations have been designed in inventor.

We also updated the milestone project, so we will be looking at and ordering materials soon.

PROGRAMER BLOG
We worked on tracking two colors live using the lab view software, we encountered a problem finding the colors during our live feed so we set up a color inversion filter to be added to the images to remove the background colors and bring out the red and fuschia that we need to find.
we will continue to work on the camera control and the function of color location next time.