non-pneumatic "kicking" mechanism

[RRLedford]

Since the only arrangement of elements with any structural integrity is the triangle, and since it is more efficient (less material) to apply and direct force via tension ---

Our kicker is an aluminum triangle "pendulum" made of tee-slot channel with gusset plates at corners and a "toe" on low corner for ball contact. Triangle's top corner clamps to 5/8 axle through ball bearings. At low corner of triangle is attached a 1500lb test 1/8 x 1/4 synthetic cable that runs through forward mounted pulley which turns cable rearward, toward bank of bungee cords, pre-tensioned to ~50LBS. Rear corner of triangle has strong travel stop cord attached to solid frame anchor point. It stops the kick at end of travel, and it sustains the minimum pretension force on bungees.

On its path rearward to the bungee group, the kicker cable passes through a winder plate that is driven by a geared down CIM motor to ~12RPM. Winder rotates 0-180 degrees in just over 2 seconds to shorten tension cable up to 12", depending on desired kick strength (bungee tension rises to ~120Lbs at max.). Kick is triggered by instant disengagement of winder cable from the winder plate using 2" of pneumatic cylinder piston travel to actuate the disengagement. The kick can be triggered at any point in the wind up cycle from 0-180 degrees. The trigger design is a very simple medieval-type concept and there are no other masses accelerated during kick, except the kicker & cable, and that is all I can say about it.

We are waiting to finish the gear box setup for the winder to confirm what level of wind torque it can hold while motor is de-energized. If de-energized motor allows winder to UN-wind, another system will be needed maintain the wind up tension/torque while waiting for the right moment to launch a kick.
Will confirm results of gearbox test when finished.

So far, our kicker has consistently placed shots within a 30" dia. circle at 35+ feet. We still need to "possess" balls well enough to maintain this level of accuracy during match play, and this remains the bigger challenge. We do expect to be able to consistently score two or more goals from far end in autonomous mode.
-RRLedford

[sloteera]

Here you can see our kicker.

http://www.chiefdelphi.com/forums/sh...highlight=1860

Without pneumatic systems. Only a CIM motor with gear box!!

[Matt382]

Our kicker is powered by surgical tubing right now, but for competition we will find something stronger. We pulll it back with a window motor, and we have this sort of locking ratcheting mechanism which we will release with another window motor. Our range is looking to be around 40 feet, but it's variable on how far back we wind up the kicker.

[lynca]

Originally Posted by Ether

Mind posting a video ?


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The team from Chile posted a good toughbox kicker video.

http://www.chiefdelphi.com/forums/sh...d.php?p=911126

[Chris is me]

Originally Posted by Matt382

Our kicker is powered by surgical tubing right now, but for competition we will find something stronger. We pulll it back with a window motor, and we have this sort of locking ratcheting mechanism which we will release with another window motor. Our range is looking to be around 40 feet, but it's variable on how far back we wind up the kicker.

You won't get much stronger than surgical tubing, but if you're looking for more repeatability, bungee cord exchanges a little force for more consistency.

[Ether]

Originally Posted by Chris is me

... if you're looking for more repeatability, bungee cord exchanges a little force for more consistency.

Hi Chris,

I was wondering if you read this somewhere or if your team discovered it by testing.

Thanks.


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[Chris is me]

Originally Posted by Ether

Hi Chris,

I was wondering if you read this somewhere or if your team discovered it by testing.

Thanks.

I have read on Delphi that the spring constant of surgical tubing is very temperature-dependent. I've also heard from others' testing (at this time I don't remember who) that their surgical tubing powered prototype had issues with consistency.

[Ether]

Originally Posted by Chris is me

I have read on Delphi that the spring constant of surgical tubing is very temperature-dependent. I've also heard from others' testing (at this time I don't remember who) that their surgical tubing powered prototype had issues with consistency.

OK thanks. Just wondering, did either of these sources compare the consistency of surgical tubing to bungee cords?


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[waialua359]

I'm not so sure that the use of bungee cords sacrifice force when compared to surgical tubing.
You can easily make up for it by applying more/different bungee cords to achieve the force you are looking for. If consistency and durability are better with the bungees, its a no brainer, right?

[viper110110]

Our kicker is going to be a large spinning blade/paddle thing. We will be able to adjust the speed/turn it off at will, allowing us to control the ball how we want to. Our tests give us about 10-15 feet, but we are changing the kicker mechanism now to have a larger paddle and possibly 2 motors.

[Ether]

Originally Posted by waialua359

If consistency and durability are better with the bungees, its a no brainer, right?

If.

The veracity of the premise has not yet been established.


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[Ether]

Originally Posted by viper110110

Our kicker is going to be a large spinning blade/paddle thing.

Do the spinning paddles/blades extend outside a vertical projection of the frame perimeter?


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[Ether]

Originally Posted by Matt382

Our kicker is powered by surgical tubing right now, but for competition we will find something stronger.

Just curious: why don't you just double-up (or triple-up) the tubing? That will make it twice (or three times) "stronger".


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[Matt382]

Originally Posted by Chris is me

You won't get much stronger than surgical tubing, but if you're looking for more repeatability, bungee cord exchanges a little force for more consistency.

Yeah exactly. I guess one of our team members read somewhere on CD about harpoon gun tubing so now one of our mentors plans to get us a few different diameters of the stuff so we can figure out what works best. There are a lot of stretchy materials to use, and surgical tubing is probably not the ideal material.

[spacegy4]

The spinning wheel is in! We call it the spinning tounges of death!

http://cms.team639.org/node/113