Pnumatic Rules Suggestions/Gripes
 

Over the summer i have been working for a pnumatics company. The other day i was thinking about FIRST and realized that the pnumatic systems involved in FIRST robots seemed almost silly and absurd after the things i have been working on. I laughed when i whough about the cobbled together mass of disposable cylinders and haphazardly strewn about valves by different manufacturers. I would like to hear what other peoepl think about lifting some of the pnumatic restricions. Below are some of the areas whre i have a problem and what I would do to change them if i were supreme dictator of the first world.

NEGATIVE PRESURE SYSTEM RESTRICTIONS:
Ok this is the big one. This is what really prompted my post. I have worked with vacuum handling systems for microchips, cardboard boxes and water bottles all the way up to full 80 gallon drums. I have been amazed at how useful and how versatile, effective and at the same time how simple such systems can be. I think that FIRST should allow Vacuum generators and suction cups.. This alone would open a whole new dimension to they way FIRST robots manipulate things... If there were two components that i could have added to the KOP, they would be a vacuum generator and a suction cup. Its unbeliavable how easy it is to pick up just about any object with these things.. Of course, Vacuum generators are somewhat of air hogs. We would either need a higher primary side pressure, larger accumulators or a beefier compressor. I havnt' done the math, but matches are rather short, and It seems to me that if we were given larger accumulators we would be okay. The past few years, FIRST has allowed us to use cups with integrated vacuum generators, so why not allow us to seperate them. If you can come up with any reason whatsoever why we should not be allowed to sue vacuum systems, I would love to hear it.

ACTUATOR RESTRICTIONS:
Why are we limited to what are more or less bottom of the line plain jane cylinders. There are many places whre a rodless cylinder, Pnumatic gripper, multipostion cylinder etc would be of great benefit. It seems to me that the reasons behind most of the actuator restrictions are safety related. Chioces do not have to be sacrificed to achieve this. If i were supreme dictator of the FIRST world, i would allow any actuator by any manufacturer so long as if fell within a certian maximum output force criterion.

VALVING RESTRICTIONS:
I think teams should be able to use whatever valves they want so long as things come to rest when the E-Stop button is pressed (IE: everything electrically actuated. No air piloted valves and air logic.) Actually on second though i think teams should be able to use all the air logic, porportional valves etc they desire. The following is a common practice in industry and someting that could apply to a first robot to allow some of the pnumatic restrictions to be safely lifted. We have a NO 3-way single solenoid valve controlled by a spike relay. Port one( input) is plumbed to the output of the primary regulator. Port 2 is connected to to all downstream components. Port 3 is vented. When the robot is disabled, so are spikes and thus our safety valve. No compents other than the compressor, primary regulator, and acumulators have any pressure. Everything else is vented Once the robot is activated, the valve shifts and everythign gets pressure.

I'm getting bored of writing now, and i havn't proofread any of this, so if it makes no sense o well.. I'm not sure how many peope hang out on these forums during the summer, but if there is anybody here, I think this would make for an interestin discussion and i am eager to hear other peope's opinions.

Re: Pnumatic Rules Suggestions/Gripes
 

I'm no pneumatics expert by any stretch, but I distinctly recall seeing a few Palmetto robots using suction to handle the 2X balls. 1398 (Keenan HS RoboRaiders) had the system going, but I don't remember how well it worked.

I do remember the Firebirds' setup quite well. I remember them building an air pump using a kit motor of some kind and using it for suction for their cup on top. They capped quite a few times, although I seem to recall the setup releasing the magic smoke once right at the end of a match.

Can anyone more familiar with either help jog my memory?

Re: Pnumatic Rules Suggestions/Gripes
 

I know that 69 had a suction device, although I have no idea how it worked.

Re: Pnumatic Rules Suggestions/Gripes
 

The current pnumatics rules DO allow for vacuum systems which generate negative pressure by using a System in which suction is generated by pressurizing one port of a cylinder, and using the suction from the other. This Can be efficient in terms of air usage if done properly, but is VERY bulky compared to venturi pumps and can be a bit of a hassle.

Re: Pnumatic Rules Suggestions/Gripes
 

I know this may sound like a stupid question but isn't a venturi pump the same way the automatic fertilizer mixers work.

Re: Pnumatic Rules Suggestions/Gripes
 

I'm not sure how an automatic fertilizer mixer works, but a venturi pump is pretty simple. In its most basic form, have a T-junction of pipes, blow air down the not-dead-end pipe of the T and you have negative pressure on the dead-end pipe.

Because of Bernoulli's principle (faster fluids have lower pressure than slower ones), The speed of the driving air cause's its pressure to drop into negative range. The T junction lets you access this negative pressure.

Re: Pnumatic Rules Suggestions/Gripes
 

Re: Pnumatic Rules Suggestions/Gripes
 

Yeah thats the whole concept. The negative pressure is used to suck up the fertilizer. I can't believe no one has used one. They hook up onto the hose. Only reason why I asked is because my uncle told me that the mixer uses a venturi straw. Why can't someone build a venturi pump. It really doesn't seem that hard.

Re: Pnumatic Rules Suggestions/Gripes
 

To build a Venturi Pump would be reinventing the wheel. They are readily available off the shelf. Building a venturi pump the quality of those commercially available would be very difficult. It has taken years of developement to get to the level of design tweaking they are at. most use several stages and valves which open and close to adjust to varrying vacuum conditions (IE: they put the stages in parallel when high flow low vacuum conditions are encountered, and in series when high vacuum is needed). I really can't figure out why FIRST doesn't want us to use these. They present no safety hazard, and could be of great benefit.

Re: Pnumatic Rules Suggestions/Gripes
 

If you went to the pneumatics meeting at Atlanta we talked about some of these things. There is a company, can't think of, someone jog my memory that was looking into donating venturi style vaccum generators that weighed less than a 1/4 pounds, barely used any air, and had tremendous suction. If someone else knows the companies name and the device name clue everyone in. But this would solve everyones suction needs.

Another thought is raising the restrictions on the number of accumalators. This would give some more room to store air. But you got to be careful so that you aren't jeopardizing the pressure of the system.

About valve I see that it would be nice to have more options but still keep the creativity in it. You can still do a lot with what they have this year. And general restriction were fairly loose.

And for different kinds of actuators. They are honestly working to get you the best and most useful actuators. They added the rotary actuator and the actuator with magnectic reed switches(common in industry) this year and look for more ways to get us the equipment we want and need. I'm sure if you wrote out the actuators you thought would be the most beneficial, and cost efficient as a donation, and got the list to the guy who gave the presentation at the pneumatics workshop (name escapes me, look it up under the FIRST convention) he would be willing to talk, take input, and see what he could do about getting FIRST the best possible kit.

Re: Pnumatic Rules Suggestions/Gripes
 

The example you cited is important for safety in industry, a critical need to dump all energy sources. While this is a common practice in industry it may not directly apply to FIRST. Many teams, including ours, use the air pressure in the disabled mode to position a part of the robot at the beginning or end of the match. This years example is all the hangers that withdrew their feet when the match ended.

Re: Pnumatic Rules Suggestions/Gripes
 

I have so many comments and ideas on this topic I dont even know where to start.

I have been doing research and such in pnuematics pretty actively for the past year or so. I have generated suction systems, recycle systems, multi-positioning systems and many more.

I could be wrong but I don't recall the use of venturi pumps being illegal this past season. In fact I think that may have been what team 69 used. I know for the offseason competitions we have been developing a suction system for manipulating 2x balls. To do this we have integrated I have integrated a venturi pump into the system and it works beautifully. To stop the flow of air through the pump all you have to do is place a solonoid on each side of the pump, that way you can turn your airflow off and still hold onto whatever object you are grappled onto(at least thats the way we have to do it with the pump we have).

As far as valve restrictions I tend to disagree with rickertsen's 3 way valve. This problem with it is that in a machine that uses lots of pnuematics(ie. 134 bot this past season which ran only two motors) it takes time and power to charge this system. Having a 3 way on a machine like that counters some of your previous arguements. (i could have misinterpretted you however)

Otherthings id like to see changed is that i think you should be able to make your own custom air containers. Using Copper piping to create an accumulater might be lighter than current accumulators and would be cheaper. To test for leaks in my current job (running pipe with plumbers) we pressure the system well over 100lbs of pressure and the pipes hold with solder. Its and economical solution that is cheap and allows for custimization of a system.

Ill prolly come up with some more stuff...
So please ponder some on these thoughts

-Pat

Re: Pnumatic Rules Suggestions/Gripes
 

I assume that the pipes you refer to are water pipes. There is a world of difference in the failure of a hydraulic system, such as a water pipe filled with water, and that of a pnuematic system. Pnuematic sytems are considered "pressure vessels".

A pressure vessel refers to any container that encloses material that tends to continue expanding when pressure is released. Pressurized air and steam are common examples.

Let's look at a vessel like an one of our accumulation tanks. Let's say you were to fill it with water, pressurize it and then seal it. If the accumulator should start to fail, then as soon as any water leaked out, the pressure will be relieved and the failure would stop. This happens nearly instantaneously.

Now let's try it again with air. Here when the leak starts, the pressure remains nearly the same as what it was before. The failed part continues to fail because it remains under load. There is a good chance that eventually something is going flying in a random direction in this scenario.

The design of pressure vessels is strictly regulated and can only be legally performed by people who are qualified by the State to do so. Those people are Licensed or Registered Mechanical Engineers (the exact term varies by state). There are a few of them running around here on CD, I am one of them, Dr Joe is another. I don't think either of us is familiar enough with the ASME boiler code, which regulates the design of pressure vessels, to be able to design our own and be sure of meeting all of the requirements. The companies that make pnuematic hardware are knowledgable about the code and follow it pretty strictly. It is the "standard of practice" in this area and not following it leaves you pretty wide open for liability suits should anything go wrong. Not to mention the fact that people might get hurt.

It is interesting to note that the ASME Boiler Code came about because somebody noticed around the turn of the century that boiler explosions were one of the top ten leading causes of death. The ASME decided that they should codify the best design practices and eliminate this entirely preventable calamity. This approach has been extremely successful. The last time I even heard about somebody even being injured in a boiler accident was ten years ago and it involved an antique steam locomotive that may have been built before the Code was created.

So there are darn good engineering reasons NOT to have you guys building your own custom tanks etc. In my opinion, it is the pnuematics, not the electronics, that have the highest potential for injury on a FIRST robot. So treat them with the respect they deserve and don't "meddle in the affairs of wizards".

Re: Pnumatic Rules Suggestions/Gripes
 

Ugghh... Pneumatics.. My second least favorite system on the robot next to Electronics.

Anyways, personal opinions aside, let's look at this from another standpoint.


If you were designing a game for HS kids to play/compete in, and you also got to choose the parts they use... then.. would you:

A) Let them (the HS kids) have free range and give them anything they wanted to use which would defeat the purpose of learning how things work and teach them only how to assemble parts together to work.

or

B) Would you restrict the supplies to the most basic of fields, (Pneumatic -tanks, regulators, hoses, compressors, etc...) (Electrical - chips, wires, switches, etc..) (Mechanical - Metals, Plastics, Woods:rolleyes: , etc...) Then the HS kids would have to make their own system (ie: robot) to whatever possible combinatoin of the basic parts they have available.

I personally would choose B. It's not what you can do sometimes, it's how you can accomplish it that seperates the thinkers from the assemblers.

Granted, I would love to use a ready built component rather than make one myself, but in a competition based on learning and inspiration.. Isn't that defeating the point??

Re: Pnumatic Rules Suggestions/Gripes
 

I think elgin and chrish hit a lot of good points.

FIRST is working to give us the safest and most effective parts they can give us. At the pneumatics meeting we talked about a compressor that weighed 1/3 the weight but wasn't as fast at recycling. We talked about lighter accumulators more like a PVC type. We talked about more accumulators. These things are all taken into consideration. Most of all FIRST wants us to be safe and follow good design practices.

And this is about design. I always love to see what new things teams come up with. I've been proud to have suction (non-pneumatic) this last year, and multi-position actuators the previous. It took some thought but worked out great in both cases. Elgin really gets to this one. Do you want it to be the best robot or the best engineered. Like Dave said at Atlanta. We are going to have a certain amount of parts we can use on Mars and we've got to make them work. We can't go to the hardware store and buy it completely finished and ship to Mars. Same here. I like some freedom. But the constraints make the game interesting. IMHO.