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-   -   Team 871/Grippers (http://www.chiefdelphi.com/forums/showthread.php?t=2433)

Chubtoad 26-02-2002 12:11

Team 271 Grabber
 
Team 271 Grabber

If you want to go to the Bay Shore site, there is a pic of the whole bot, we will be updating it soon, but with school I haven't gotten the chance to. Also soon a movie of the bot working.

Trust me on the fact that those grabbers are robust. and yes once they grab the goal they pull it into the bot.:D

aka Scott White 26-02-2002 12:27

We have a very similiar gripper
 
Our gripper is very similiar to team 93's. Except for the pneumatic pushing it down to be level with the playing field, our arm functions with no assisstance from the rest of our robot, and as far as we can tell, as close to guaranteed to work as it is possible to be; its spring loaded, and cannot detach from the goal without manual asstance after the match.

Greg Needel 26-02-2002 13:15

we agree with KISS
 
1 Attachment(s)
as far as my team goes we definatly agree with kiss. so here is our simple grabber I'll post a better pic when I can find one

Wetzel 26-02-2002 16:06

Team 271, you may want to consider adding some shielding at your regional, if you havn't already. I'm looking that the speed controler in the lower left in particular.

Joe Johnson 26-02-2002 16:29

How much side load before failure....
 
My biggest nightmare is the sideload issue.

Specifically, how much of a load can the gripper take before it plastically deforms your gripper (or the guide system which is just as bad and perhaps even worse)

We initially had a very basic structure. When we analized the loads, we discovered that it would deform plastically at about 200 pounds of side loading. We decided that this was too close to the edge. Afterall, we can put more than 200 pounds of force on the goal all by ourselves in a static load condition, a dynamic load case in the heat of battle will very likely exceed 200 lbs.

In the the end we compromised at 500 pounds designed side load (with a bit of a safety factor thrown in for good measure). It made our mechanism (and our guide system) a little more complex, but in then end, I think we will have a trouble free mechanism.

Every team will have to decide where the right balance between KISS and a robust & reliable mechanism.

Time will tell how well each teams has balanced the scales...


Joe J.

Chubtoad 26-02-2002 20:41

hmm, never thought about a robot coming in that way, the goal comes no where close to that, the reason it is so close to the edge is actually cause of weight;) we were lucky though, when we cut those sections out, (which if you look from the front as in the other pic on the website Looks like two "M"s which is Cool cause our initials are MM) it made the robot look a lot cooler!
Thanks for the idea though, i'll defintly see if we can add some protection there. We added a piece of corrogated lexan (think cardboard, but lexan instead) over where the balls would drop from our basket (if we weren't over a goal) to protect electronics, but I am going to try to convince them to make sure we move it to a casing over the whole main section

As far as side loads, we made reinforcement sections on our entire robot, to compensate for any directional force we could think of. So we hoping ::wink wink:: that it holds up. We are actually currently making a copy of the robot we shipped to test stuff out and practice with, we have the whole drive system done, which is good cause in practice today we sheared a pin, so we are making a list of things we have to change once we get to our first regional!

Anybody else have comments on 271's grabber?

Ragin_Kage 27-02-2002 20:38

I think my team will be notorius for our goal grabber designs...We've got a "Twist n' Lock" in the front and two "Battle Axes" on the sides.... http://middlesexboro.net/powercord/pictures/146.JPG

there are more pics on our website

we are rookies, so watch out for us in NJ and St. Louis regs.

Ragin_Kage 27-02-2002 20:39

that picture is quite old, so dont worry about all our wires being exposed, we got it all under control, haha

Jeremy_Mc 28-02-2002 01:28

Weight Transfer
 
As well designed as all these grabbers are, we went through most of these concepts during our design phase(s). :) But we ultimately came up with a design that would allow us to "hug" the goal, contact it on three sides, grab it on two. Then lift up and transfer the weight of the goal in its entirity to the chassis and drive system of our robot, thus giving us MAJOR torque, traction, and frankly power. :) Also it gives up complete control of that particular goal. We added a second goal grabber that is very simple, but with the amount of torque that the goal's weight allows us, we don't need anything else fancy. ;)

Mike Norton 01-03-2002 17:36

this is the one grabber that can grab goals or robots :D
http://www.chiefdelphi.com/forums/pi...rrow=4&trows=3

this one will grab a goal and not let go;)
http://www.chiefdelphi.com/forums/pi...rrow=4&trows=3

this is the same grabber on the robot

http://www.valleytech.k12.ma.us/Robo...002%20Claw.jpg

We used a nice cable that will let the goal do 360 around the robot. this way we can always pull.

the first grabber let us turn 90 each way. this design has been proven out in the past to be very sturdy.


I say let the jousting begin

Matt Reiland 01-03-2002 17:51

Mike,

Looks like your motor mount may have slipped a little from the 1st picture, the sprockets don't seem aligned.

Mike Norton 01-03-2002 17:59

The big sprocket you see is warped we welded a square stock to the inside of it. we used this only to test it out. We have another one that does line up nice.


48 or a 24 tooth that will be what we will be thinking of.



48 is fast and powerful, powerful enough to move the goal as it comes out.

24 is slower but much much stronger this can crush thing. Only use will be if things get rough.


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