pic: 1747 Answer to Teaser

CD-Media: Photos
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#1

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This is a picture of 1747s kicker mechanism. It utilizes a carbon fiber “leg” attached to a wooden “foot” with an easily-changed pitch angle. The pivot will be attached to the top of the robot, near the 18-inch mark, and will be pulled back with a winch mechanism (pic to come soon). When released, surgical tubing will kick the ball with a >60 lb force, able to clear two bumps at full capacity.

The 8-ply carbon fiber’s springiness, while light for its strength, will provide additional follow through and a greater transfer of energy to the ball, which is a problem we had with aluminum.

#2

How much did the carbon fiber actually help? I’m interested as to see if our team should use them. We’re currently using aluminum for the kicker assembly, but perhaps this will help significantly. But ours is completely pneumatic, so perhaps not…

#3

Neat! I hope the added follow thru remains within the bumper perimeter :slight_smile:

#4

We have yet to complete testing while using the carbon fiber, but it appears to be giving us an additional 4"-6" in height and about 2’ in distance, which is significant as far as we are concerned.

During testing we discovered that the follow through on the kick was very important, and the little bit of extra given by the follow through is definitely what is needed.

As for staying within the perimeter, we will not be violating the 2" rule, and we will only be outside the perimeter confines of the robot for a fraction of a second, so we will be good to go!

#5

When released, surgical tubing will kick the ball with a >60 lb force…

How, or should I say where, are you attaching the surgical tubing to the robot and the kicker? :confused:

#6

The surgical tubing passes through the i-bolts at the bottom of the kicking leg. Both ends of the surgical tubing are tied to the front of the chassis.

#7

OK, that makes sense as long as the kicker arm is mounted at least 3 inches behind the front of the frame.

#8

I would epoxy some washers right onto the CF part, it can crack very easily with fasteners going through it.

Looks sick though! I love CF parts, it’s an incredible material.

#9

/noted

Thanks!

#10

I should have noted that I not only read about it, but found out about it when a vibration experiment using CF failed on me in college:eek: .

If you ever break it you’ll learn what “catastrophic failure” really means! :smiley:

#11

You may want to look at the carbon fiber laminate over birch wood core material from Dragon Plate. Their analysis is that you only need the CF at the outer surface - not solid CF- to get the suitable stiffness characteristics. May also help further with your energy transfer issues too.
LINK => http://dragonplate.com/ecart/categories.asp?cID=3

For our kicker element, we are using an ~12" equilateral triangle, in a vertical plane, made from 20mm square tee slot channel. A widened toe at lower front corner contacts the ball and is beveled for some loft. This triangle pivots from its top corner, and has a vertical 1500lb line (1/8" x 1/4" - synthetic, low stretch) attached to its rear corner. It also has a forward travel limiting tether attached the low front corner.
The synthetic line is bungee pre-tensioned to ~50 Lbs of pull, and a CIM driven winder can draw line further back to reach 100+lbs tension. Triangle kicker element is accelerated very rapidly with minimal arc of travel to give full-field kicks. Triangle kicker element reaches high velocity and has ZERO FLEX on contact with ball (triangle is the ONLY structural shape) , thus acheiving maximum compression of ball’s surface during ~1/100th second of contact with ball. This high sustained velocity during short (1/100th second) period of contact with ball is more important than follow through, and is is the single most critical factor for long distance shots that we have yet determined.

-Dick Ledford, Robotic Colonels Mentor

#12