Team 842 Testing Shots

[sergioCorral842]

Here are some different shots we were testing today:
http://www.youtube.com/watch?v=ldO02ByEn5o

[dradel]

How are you guys varying the pressure the cylinders launch at?

[dodar]

I'd guess they have multi-stage pneumatic cylinders.

[s_forbes]

The pressure is held constant for all of these shots - 60 psi. There are some tricks you can do in software to adjust the trajectory.

[calvinstence]

I believe what they do is vary the air pulse timing in code- I remember hearing them talk about this in one of their videos.

[Mr. Lim]

The pressure is held constant for all of these shots - 60 psi. There are some tricks you can do in software to adjust the trajectory.

This is brilliant...

::rtm::

[falconmaster]

This is brilliant...

::rtm::

Its a lot of fun!

[yash101]

Yeah, and I think you have already scared a 1165er!

[Michael Corsetto]

This is awesome! You guys are hitting all of the shots we hope to, but without all the crazy mechanical stored energy.

Question, in your testing, how many tanks are you running with, and how many shots do you get before needing recharge? Is the compressor able to "keep up" with how fast you're taking shots? It looks like in a short time you are making some shots quickly, just curious as to how much air this shooting method requires.

Very cool, will no doubt be highly effective, and very simple!

Can always count on 842 to come up with some innovative solutions, and then share them in order to inspire the rest of us! Thanks!

-Mike

[AllenGregoryIV]

Love this setup. That last shot, should be pretty much impossible to stop and completely repeatable. That has been on our list of shots we need to have.

[Johnny]

What are the bore sizes on those cylinders? Can't tell if it's 1.5 diameter or 1 1/16. Looks identical to what we have gotten so far. Good job guys! Looks awesome!

[sergioCorral842]

Question, in your testing, how many tanks are you running with, and how many shots do you get before needing recharge? Is the compressor able to "keep up" with how fast you're taking shots? It looks like in a short time you are making some shots quickly, just curious as to how much air this shooting method requires.

-Mike

We can shoot about 2-3 high goal shots from the middle of the field before the compressor needs to turn back on.

What are the bore sizes on those cylinders? Can't tell if it's 1.5 diameter or 1 1/16. Looks identical to what we have gotten so far. Good job guys! Looks awesome!


They are 1.5 in diameter.

[Mr. Lim]

What kind (make/model #) of solenoid are you using?

I'm assuming it's a double acting. What is the center position of the solenoid? A and B both closed? Both to Exhaust? No center position?

How are you precisely varying the timing of the pulse to the solenoid? Are you just counting cycles in the teleop periodic loop? Does that limit you to about 20ms increments? Do you need anything more precise than that?

So many questions...

This is very cool stuff.

[s_forbes]

What kind (make/model #) of solenoid are you using?

I'm assuming it's a double acting. What is the center position of the solenoid? A and B both closed? Both to Exhaust? No center position?


Nope. :)

Here's a part number for you though (see mcmaster): 6124K511


How are you precisely varying the timing of the pulse to the solenoid? Are you just counting cycles in the teleop periodic loop? Does that limit you to about 20ms increments? Do you need anything more precise than that?

So many questions...

This is very cool stuff.

I'll let Sergio get back to you on the pulse control... I'm not sure how fast his program loop cycles.

[rai337]

Hey there, nice job you did there! Looks amazing, and very powerful :)
We wanted to ask a few questions:
1. What is the length of your chasis?
2. What is the length of your pistons?
3. Is there any specific reason why you put your pistons in such starting angle? Did you find that angle more effective than others?

Good Luck, and see you at the competitions! ;)

[Ether]

Is there any specific reason why you put your pistons in such starting angle?

With a motor, you use a gearbox to trade speed for torque.

With a pneu cylinder, you use leverage to trade force for speed.

[Bewizardment]

How are you guys loading the ball? Does the arm go down further?

[sergioCorral842]

How are you precisely varying the timing of the pulse to the solenoid? Are you just counting cycles in the teleop periodic loop? Does that limit you to about 20ms increments? Do you need anything more precise than that?


This is very cool stuff.

I basically use the Timer class. It does not seem to be having any issues with that.

[Duncan Macdonald]

That pile of broken ceiling tile has nothing to do with the robot right?

[sergioCorral842]

That pile of broken ceiling tile has nothing to do with the robot right?

Robots*

[Team 2016]

Could this be used to pass or catch?:confused:

[Joey1939]

I basically use the Timer class. It does not seem to be having any issues with that.

Could you please explain in greater detail how to implement this?

[sergioCorral842]

Could you please explain in greater detail how to implement this?

Use the timer class to set the pistons to true for a certain amount of time then set them to false right after.

[JohnFogarty]

The amount of inspiration this video has given me cannot be quantified.


What solenoid are you using? is there any special storage tank between the solenoid and the cylinder? Or is it just


Compressor ---> Pressure Sensor -----> Storage Air Tank ----> Regulator ----> Solinoid ----> Cylinder.

*Forgive me for my lack of pneumatic knowledge if that order is so wrong that I deserve to be flogged.

[kuraikou]

Super cool!!! I look forward to seeing you at the AZ regional.

In the videos your team posted on Facebook you have another piston that goes up and down as you fire, what is the point in this and how does it work?

[falconmaster]

The amount of inspiration this video has given me cannot be quantified.


What solenoid are you using? is there any special storage tank between the solenoid and the cylinder? Or is it just


Compressor ---> Pressure Sensor -----> Storage Air Tank ----> Regulator ----> Solinoid ----> Cylinder.

*Forgive me for my lack of pneumatic knowledge if that order is so wrong that I deserve to be flogged.

Compressor, pressure sensor, primary storage tank, regulator, secondary storage tank, solenoid, cylinder

[s_forbes]

In the videos your team posted on Facebook you have another piston that goes up and down as you fire, what is the point in this and how does it work?

That additional piston gives us the ability to adjust the trajectory further. Just by varying the pulse to the main catapult cylinders, we are able to make a relatively lofty truss shot and a pretty hard/flat high goal shot. The geometry of the arm for those shots doesn't work for the in-front-of-the-1pt-goal high goal shot, so we added another degree of actuation.

We did a few quick tests today that make a self caught shot over the truss look feasible using these additional pistons; it will be pretty neat if we can pull that off in a match!

[mithril865]

First let me say how impressive this design is. The flexibility is incredible! Can you please provide more details on how you implemented it including cylinder dimensions (bore & stroke), release, distance cylinders are attached from the pivot, pneumatic connections, are you using 2 tanks per cylinder? are you using separate solenoids for each cylinder? Our team tried to replicate your set up tonight and couldn't get anywhere close to the range you demonstrated.

Thanks...

[waialua359]

Our team used a different mechanical approach to varying our shots with the same shooter mechanism.
After seeing this thread early yesterday, we have already tried with great success the software pulsing of the solenoids instead.

Thanks for sharing.

[nuclearnerd]

OK, we had similar size cylinders, similar sized catapult, and tanks directly connected to the cylinder ports (mechanical release - we didn't even get into large CV solenoid valves yet) and we could not make our shooter make long shots like yours. We clearly have some learning to do. I'm looking forward to seeing more of your system after build season!

[AdamHeard]

OK, we had similar size cylinders, similar sized catapult, and tanks directly connected to the cylinder ports (mechanical release - we didn't even get into large CV solenoid valves yet) and we could not make our shooter make long shots like yours. We clearly have some learning to do. I'm looking forward to seeing more of your system after build season!

A very small difference in the geometry can cause a huge launch difference.

[matthew_martin]

So you used 1.5" bore cylinders, but what stroke did you use? We've looked at a couple ideas, but with our current configuration, ours couldn't fit.

[falconmaster]

So you used 1.5" bore cylinders, but what stroke did you use? We've looked at a couple ideas, but with our current configuration, ours couldn't fit.
9 inch stroke