07-02-2007 00:07

Lil' Lavery

Re: pic: Team 319 - Big Bad Bob's Lift System

Do you expect any trouble with your center of gravity if only one "wing" is occupied by a robot when you raise up? Basically, if only one side is loaded, you might tip over.

07-02-2007 00:12

Ty Tremblay

Re: pic: Team 319 - Big Bad Bob's Lift System

If you look on the left wing, almost hidden by the table, there's an outrigger piston that fire's with the other 4. We figured if there's only one robot, they'll get on that side, problem solved. Oh yeah, we cruched the numbers, and we theoretically have 700+ pounds of lifting force.

07-02-2007 09:33

Brandon Holley

Re: pic: Team 319 - Big Bad Bob's Lift System

thats a lot of pneumatics.......how long does it take you to fully complete a lift?

07-02-2007 10:46

Pjohn1959

Re: pic: Team 319 - Big Bad Bob's Lift System

We are using two of the same 2" cylinders. However, due to the tank restrictions, we can only deploy one at a time. How are you planning on using as many as you have at the same time?

07-02-2007 12:15

Ty Tremblay

Re: pic: Team 319 - Big Bad Bob's Lift System

We just lowered our working pressure. At 60 psi, the 2" pistons crank out almost 200 pounds of force. We don't need 800 pounds of force to lift two 120 pound robots, so we lowered our working pressure to 30 psi. Giving us about 80 pounds of force per piston. This gives us twice the amount of air to work with and we still have enough force to lift two robots.

P.S. We haven't done a complete two robot lift yet, but it shouldn't matter. The pneumatic solenoids require power to switch in and to swith out, thus if we push the "up" button even a millisecond before the end of the match, it will still go up.

P.P.S. Our lift platforms and the feet we put on our pneumatics are removable. So, if there is a robot in our alliance that can lift better than us, we just remove those parts and we have almost 2 inches of clearance.

07-02-2007 12:51

Pjohn1959

Re: pic: Team 319 - Big Bad Bob's Lift System

That's cool!!!!
Good idea to lower the pressure. We found that the 2" pistons only dropped the air pressure by 18 pounds when actuated. We are able to lift 200 pounds on each ramp using just one piston.

07-02-2007 13:04

Lil' Lavery

Re: pic: Team 319 - Big Bad Bob's Lift System

Correct me if I am mistaken, but it looks like the pistons raise your robot as well as the other two? So, given the max weight of a robot being ≈148 lb. (120+13 battery+15 bumpers), wouldn't you need at least 444 pound of upward force? The 4 central pistons each producing 80 lb.s only gives about 320 lb. of force. Even if the outrigger piston is also 2 in. (which it doesn't appear to be) that's still only 400 lb. of force.
Is there something I'm missing?

07-02-2007 17:08

Ty Tremblay

Re: pic: Team 319 - Big Bad Bob's Lift System

We just did a test, and at 60 psi, we lifted two 200 lb kids. Add in our robot, and you have almost 550 lbs to lift. Plus we have air left over. I don't know why the other person can't fire both at the same time.

07-02-2007 19:05

hayakuneko

Re: pic: Team 319 - Big Bad Bob's Lift System

hey u guys i have a question about the arm. if the arm is stored just like in the picture and there is a pneumatics cylinder on the ends of the wings (also like in the picture)... when the wings are stored how does the arm get its full range of motion?

07-02-2007 19:17

coldfusion1279

Re: pic: Team 319 - Big Bad Bob's Lift System

clever idea with the pneumatic distribution, hope it works well for you. Also great idea to make them detachable, we might have to adapt that to our robot

not trying to cause any fights, but lil lavery try and be more supportive of teams.. i read your posts all over the place and you are constantly trying to figure out why things arent going to work... this is FIRST, we are putting innovative thinking to the test, ive seen some strange ideas become some of the best robots. keep posting tho, just be aware of what your saying.

07-02-2007 19:48

Salik Syed

Re: pic: Team 319 - Big Bad Bob's Lift System

I'd rather be warned than have a system fail, but people generally tend to know what they are doing.
Great idea, I like the fact that it can be deployed 1 second before the match ends... could very well come in handy!!!

07-02-2007 19:51

lukevanoort

Re: pic: Team 319 - Big Bad Bob's Lift System

I haven't really noticed Sean being any more critical than others, but if that was the case, I think you misinterpret his intent. In a lot of cases it is very easy to make a mistake in your design or overlook a simple problem, and it is usually a good idea to ask about things that seem sort of risky or such, in the case that there is a mistake, or if there isn't one, to satiate ones own curiosity about how the limitations of a design were solved. For example, in this case it is very easy that the weight of the battery and bumpers weren't included in calculations. However, it appears that there was a bit on miscommunication in posting this time.

07-02-2007 20:37

Lil' Lavery

Re: pic: Team 319 - Big Bad Bob's Lift System

I'm sorry if my posts have come across as aggression or sarcasm, when my intent is often merely either confusion, curiosity, intrigue, or concern. In some cases I post that something may have an issue, because, well, it may. It's better to be warned early than too late. I also often post about how teams have solved particular issues elegantly, the advantages of certain designs, or how a design reminds me of successful deigns in the past.
In this case though, 30 psi wouldn't have had enough force (as it was stated they may be using), but the 60psi they later said they were using generated plenty of force. Luckily here, there was no issue.


Back on topic. What kind of material are you going to put on top of the "wings" and what method are you using to deploy them?

07-02-2007 20:51

Ty Tremblay

Re: pic: Team 319 - Big Bad Bob's Lift System

We have expanded aluminum going on top of the wings. But it was too heavy so we cut a series of diamond patterns out of it, making it perforated expanded aluminium. The platforms fall on their own, so we just pull a pin with a servo.

07-02-2007 20:59

Ty Tremblay

Re: pic: Team 319 - Big Bad Bob's Lift System

There's only one 12" long x 2" bore outrigger piston (we figured that if we were going to lift 1 robot, we would tell them to get on that side). Therefore, the arm can go around it when it deploys in autonomous mode.

07-02-2007 21:03

Greg Marra

Re: pic: Team 319 - Big Bad Bob's Lift System

Are you worried about teams pulling out the pneumatic hosing running to the outer cylinders or hitting and damaging the cylinders themselves?

07-02-2007 21:37

Dan Petrovic

Re: pic: Team 319 - Big Bad Bob's Lift System

Wow!

Look's awesome, you guys!

I can't wait to see this at BAE and maybe at the Balloon Rally this year! ;D

It's amazing what a handful of students and a few mentors can do.

07-02-2007 21:57

zander_108

Re: pic: Team 319 - Big Bad Bob's Lift System

wow.... Thats really some nice engineering.. I really like the way you've put thought into the machining of near every single individual piece of aluminum. Hope to see you at the championship games!

08-02-2007 14:36

d.courtney

Re: pic: Team 319 - Big Bad Bob's Lift System

how much flex do you get in your wings when there is 148 lbs on them?

08-02-2007 14:49

Halo4life

Re: pic: Team 319 - Big Bad Bob's Lift System

How are you guys going to get the other robots onto the wings?