599D gateway reveal (pneumatic lift)

Hello all!
The first version of the robot combined a two stage linear slide lift, bottom intaking rollers, and a pneumatic claw which was actually inspired by 1103’s roundup robot. This robot participated and inadvertently won in the Viewpoint competition. Seeing that this type of robot was not suitable for the competition, we decided to go with a New Zealand style robot with a 4 motor drive and 4 motor lift for the Granada Hills competition. After brainstorming a little more, we decided that speed was an important factor in the game. We decided to redesign our whole entire robot to be centered around speed. We decided to create a whole new type of lift system to allow us to put 8 motors on our drive system. We completed our robot and participated in the CAMS competition, breaking the (old) programming skills world record and achieving the excellence award which we were aiming for. The result was the first fully functional four position pneumatic lift.
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Manipulator
The manipulator is a side intaking system (24 teeth sprockets w/ 2 393’s on high speed configuration) which was held back by a locking bar in the beginning of the match.
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This setup insured that the roller would come down quickly and would have a 100% chance of not getting caught on anything.
We found that this flap configuration allowed us to pick up a game piece even when there were already 5 game pieces in the hopper.
The extending hopper was created so that it was on the verge of flipping out due to rubber bands. So during the match, any agitation of the hopper would allow it to flip out.
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The hopper allows us to hold 6 pieces comfortably and 7 pieces when they are oriented correctly.

Lift
The lift was a 6 bar design with 6 pistons (3 each side) to push up game pieces into the 4 positions needed for the game (floor, low, medium, high).
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There lift was originally designed with 4 pistons and only needed 4 pistons to fully function, but a helper piston was added to the bottom stage to aid in pushing the pieces up.
By toggling off the pistons, we were able to achieve the preset heights.
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(In order, 30", 20", 11.5". floor not shown. Helper piston is behind the rubberbands)
We were able to achieve that combination because of the staggered set up. The bottom piston was closer to the arms pivot point, allowing that extension to reach the medium goal.

The rubber band tensioning system was also a major factor that allowed this type of lift possible.
On the bottom stage of the lift, we had a standard tensioning system (seen in the previous pictures) which helped the lift raise to the 30" and 20"
Along the back of the six bar, we also had a standard tensioning system.
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In the middle of the six bar, we had a system that allowed the lift to have low energy when it was along the floor, but lots of energy when the lift was up high.
http://sphotos.xx.fbcdn.net/hphotos-ash3/522639_409399125765896_35025421_n.jpg
In this picture you can see the rubber bands almost running across the pivot point. (Heres some physics for everybody Torque = Radius cross product Force, or Radius x Force x Sin theta) which results in low energy.
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In this picture you can see that the rubber bands are now at a 30 degree angle to the pivot point (More of an angle now at 20").
http://sphotos.xx.fbcdn.net/hphotos-snc7/577039_409399225765886_143671001_n.jpg
In this final picture the rubber bands are at 45 degrees (The biggest angle at 30").
Take note that rubber bands also lose power as they retract. This fact, coupled with the fact that the angle increases as the lift goes up, allows the lift to have an almost uniform tension with 2 pieces inside the hoppers. So the pistons are doing work to keep the lift down with no pieces inside. Without this tensioning system, the lift would only be able to carry possibly 3 pieces up to the high goal.

Drive
Our drive consisted of 6 low strength motors and 2 high strength motors geared at a 1.5:1 ratio with an 18 tooth sprocket driving a 12 tooth sprocket. (Before it had all 4 high strength at a 2:1 ratio).
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We had 2 high traction wheels in front and 2 omni wheels in the back.

In conclusion, for the world competition, we made it to the quarter finals of the engineering division, losing our 4th match to the competition champions.


Extra photos

http://www.youtube.com/watch?v=eC_pdAh-yMU
Old Programming Skills Record

Wow your robot was very well done. I cannot wait to see the robot you guys create for Sack Attack.

I have some questions…
Do you have any tips for any other teams trying to use a pneumatic arm?
Do you guys plan to use pneumatics for an arm mechanism for Sack Attack?
About how long would you say it took you guys to perfect the pneumatic arm?

Thank you !!

When connecting solenoids to pistons, make the tubing as short as possible because the air inside of the tubing has to pressurize as well. This is one problem one team had. Also make sure that the tensioning system is optimal. The pistons should be pulling down on the lift before there are game pieces in the manipulator.
This is based purely on my opinion but I do not think that a pneumatic arm would be practical for sack attack because of the amount of pieces and weight the robot would need to lift. Our robot could barely get up approximately 3 pounds of pieces up to 30". compare that to 10 or 15 pounds that you would need to lift to the 15" or 30". With that said, we will not be using a pneumatic arm for sack attack.
I think it took us 4 months to get from design to competition ready to compete at golden state.

Really amazing robot ! Good job at the programming skills ! I have a few inquires . How did you manage to fill 4/6 (?) air tanks efficiently ? Do your pistol twist or bend ? How do you prevent leakages ? Thanks !

therealcedz can probably give you more details about this, but at worlds they had to use a bike pump. It looked like it took quite a bit of effort too. :slight_smile:

I am another member from 599D and yes we did have to use a bike pump to pump air into the tanks, this took about 2 minutes and we were almost always the last robot on the field. our pistons never bent and by Worlds we had virtually no leaks.

I must say, I heard about this robot and I am very seriously impressed. I’m glad some teams are starting to use pneuamtics :slight_smile: There are alot you can do with them and Its one reason I have so many tanks on my robot. :wink:

How many tanks did you have? I think there are 6 but I can’t quite tell based on the pictures.

Overall Awesome.

  • Andrew

we did use 6 tanks:)

Awesome, Did you ever use all of it? I’m getting ready to jump into another huge design week so I might be calculating the cFm of the pistons every time they fire. To see how much air we need on board, and How much we would like to have in reserve. I will be purchasing an aircompressor to pump ours up though with the amount of volume we can have.

  • Andrew

We did use a bike pump to pump air into the system, and I found that if you are going to use a bike pump to pump the system to 100 psi, you should buy one with a thinner cylinder as opposed to a pump that is thicker. Although the thinner pump will take more time to fill the air tanks, it will require less force when the tanks are at high pressure. To prevent leaks, make sure that each tube is pushed into the connectors all the way, and also make sure the fittings on the pistons and solenoids are tightened fully. This should not require a wrench. Twisting the fittings by hand is enough. Also there are small screws on each of the solenoids. which are located on the metal plate and at the opposite side. Make sure those are tightened too.

I’m assuming your reference is to the air in the tanks? By the end of the match we probably had around 40 or 50 psi left.

At full strength how much weight were you able to lift on your arm?

We can probably, but barely lift 8 pieces At that point, we would probably have to drive the robot back and forth to get the lift to go up.

I’ve never used vex pneumatics, but i always thought that pneumatics were ridiculously strong:confused:. atleast from what i was taught in frc, pneumatics were very powerful

In FRC the pistons you use are a lot bigger, meaning there is more surface area inside that air pushes on, which means a lot more force.
The vex pistons are much smaller and have a holding force of about 12 pounds for 2" of extension. We had to increase that distance to 30", reducing the force to push the game pieces up significantly. (Actually 4" to 30" because of the double stage)

I’ve said it before, and I’ll say it again: 599D built an amazing robot. I’ve been lucky enough to have been able to see it as it was developed and compete against it multiple times (definitely a challenge). Robodox put a lot of work into fine-tuning the design over the course of five months and made a very reliable lift.

That makes sense. But is there a formula or something i can use to picture these numbers? Like with motors its (force)=(torque)/(radius). Would it use (pressure)x(area)=force? Also what’s preventing a team from using a reversed version of rack and pinions if power is an issue?