Made the ground hog bumper this evening. It will mount with two 1/4-20 by 1" bolts. Maybe 1-1/4" long if we use lock washers. Put a couple of mounting location options on them, just in case...

I have to make a last minute trip to San Jose tomorrow. I won't get back until about 9:30, so I'll probably miss you all. If Kevin isn't too swamped with Senior Project work, he'll bring the bumper.

Dean

the chains are on and working
we prototyped with carbors some steeper hopper sides with cardboard.
We also made 3 orbit balls (sort of)

I will also be taking a half day Friday to help out. Looks like we still need to pick up a chain break!

We made significant progress tonight with lowering the loader brush.
We lowered the brush wheel down 1/2" and moved it in toward the elevator assembly an 1". The brush relocation also required the drive motor mount to be relocated. Looking forward to testing tomorrow!

Tonight, Nick, Skyler, and Cassandra designed and cut out another foam groundhog. It was dimensioned at 5 inches by 21 inches. We cut it out so that it was (basically) circular. But, before we decide what material we want our final groundhog to be made of, we are going to fine tune the brush/bristle groundhog; then we will test it so that we can figure out which one will give us the best results.

For the ball harvester I think we will need to slow the intake roller down to a speed just slightly faster than our robots max speed. If it spins to fast as we come up to a moon rock it will kick it out because of the slick floor rather than pulling it in. Of course this is just a theory and needs to be tested. So if we want to spin the intake roller to match the robots max speed what RPM would we need? Below is an example of the math that I used to calculate the RPM. Some of you math wizards should make sure this is correct.

Formula for circumference is: Circumference=3.14*diameter
The formula for inches per second based on RPS (revolutions per second) and the circumference of the wheel is: in/s = RPS/circumference
RPM=RPS*60 In order to get RPM we need to multiply RPS by 60
Diameter = 5 Lets say our intake wheel/brush has a diameter of 5 inches
5 * 3.14 = 15.7in
Let’s say our robot can travel a max speed of 12 feet per second. Now let’s convert that to inches per second: Inches per second = 12 feet per second * 12 inches per foot = 12 * 12 = 144in/s
Now calculate the RPS: 144/15.7 = 9.17 RPS multiply by 60 for RPM and we get 550 RPM

Jose, James and John made great progress on turret modifications on Monday night. Why modify the turret? Due to the elevator position the turret drive motor and pinion gear would have extended beyond the 28x38 max size envelope. With the turret modifications we now have total flexibility on turret motor position. Well done, "J" team!

Last night we continued to work on the turret limit switches and encoder. We test ran the turret motor and were impressed by the RPM we have (<1 second per turret revolution!). We may want to test it with an unmodified gearbox. The limit switch bracket was completed, though it still needs to be mounted. (James is all over it!) We are still looking at encoder solutions and Daniel has designed a gear to drive the high-res encoder.

Sherbot take note: I did not have any small screws to mount the limit switches. I can pick some up today, but will not bring them until tomorrow night.

Thanks team! As Cody would put it: "Get Ballin'!!"

Dean

Thanks to team 2122 for pointing out that the gear box on the globe motor is easily modified. The output shaft of the globe motor assembly turns at approximately 81 RPM. By taking the gear box apart and removing the second stage of planetary gears we will get approximately 310 RPM. Need to count teeth on the gears to get a real number.
Removing the second stage is the easy part. Now we need to shorten the housing by .25 inches. New roll pin holes were drilled last night .25 inches up from the old ones and today one of the students will use the lathe to cut .25 inches off the bottom of the housing. Then we should be ready to go. Hopefully this will be the speed we need to turn the turret.

Text from a Chief Delphi post in case you want to understand how to calculate the RPM:
Using the planetary stage reduction formula (R/S) + 1 for each stage, where R is the number of teeth in the ring gear and S in the number of teeth on the sun gear, and counting the teeth as follows:

First stage S = 21, R = 59, second stage S = 13, R = 59, output stage S = 13, R =59,

I get motor stage reduction = 3.8095:1, second stage reduction = 5.5385:1, output stage reduction = 5.5385:1, so the overall reduction is the product of these, or 116.855:1, which agrees closely with the published figure 117:1. The published free speed is 81 +/- 7 RPM

Cody and I worked on modeling the lift drive system. Looks like we have a solution. We will need to make some simple brackets tonight and hopefully machine the drive shaft. Putting a hex end on the drive shaft may require the use of the right angle rotary table on the mill. Oh goodie!

Pulley design was also worked on and hopefully we'll turn some samples to try that out tonight.

Dean suggested that I post this team's prototype "hopper" in light of some of our own hopper design woes. It works incredibally well and is simple to design and construct. (lightweight too)

*Warning this is a youtube link and will not work at school

http://www.youtube.com/watch?v=lbjGpiIpOn0