Climbing -- battery or pneumatics?

[Tristan Lall]

If you're planning to use pneumatics to climb the pyramid, also plan on including something like this 72 L air tank and precharging it for a while.

[CalTran]

Originally Posted by Tristan Lall

If you're planning to use pneumatics to climb the pyramid, also plan on including something like this 72 L air tank and precharging it for a while.

How much does that thing weigh? If the shipping weight is somewhat accurate....that's massive (25lbs!)

[Bob Steele]

Originally Posted by Tristan Lall

If you're planning to use pneumatics to climb the pyramid, also plan on including something like this 72 L air tank and precharging it for a while.

Good points Tristan... although that tank might exceed the robot size.weight by itself... lol

Conservation of Energy says whatever work you do in moving the robot you have to provide energy to do that work... in joules...

If you make a simplistic assumption that you will be moving the center of your mass approximately 2 meters up from the floor. Assuming your robot has a mass of 68 kilograms... using 10 m/s/s as the acceleration due to gravity.... a rough approximation of the number of joules you will need to lift the robot is 1360.

Physics question for the day.... Can you store 1360 joules in a storage tank that you could have on your robot? Or multiple tanks....

This is a very basic look at the energy required... remember ...use your terms correctly... power is not energy... power is the rate at which the work is done. (Joules /second)

Now if you think you can have a tank (or tanks) that could store this potential energy.. how long will it take for the little legal FIRST pump to fill it? Also.. can you apply energy at the proper rate to do the work you want to do using this system in the time you want to do it.

Now after you get all of that done... you have to start dealing with the issues of friction (which will require more joules of work to overcome), other inefficiences in the transmission of energy etc.

If you wanted to lift this robot in 30 seconds you need to have power available equal to 45 watts (not including friction etc.)

Now if you are applying the power non-continuously (stopping at various points) you will have to adjust that power rating... say for instance you are pulling on a hook ... setting a hook ... putting the hook up to a new height... pulling again... you won't be operating at a continuous power...but if that is true... for some points you will have to operate at a higher power so now you will have to have a greater source of power... so that it can do the short strokes...

interesting isn't it?

Become an engineer and enjoy the process...

Look at what the cylinders have to do... the work they have to do...
figure out what it is and how quickly the cylinder will operate...

You are asking quite abit from pneumatic cylinders to do the 30 point climb
I am not saying it can't be done...

10 point hang with cylinders??? yes... doable...
30 point hang... difficult no matter what you do...

[mikegrundvig]

The hard part with cylinders isn't actually the pneumatics so much as the design of the climbing mechanism. A pair of 1.25" bore cylinders are more than capable of lifting our robot very easily. Due to the climbing requirement, we designed our robot to be under 100 lbs with both battery and bumpers.

Assuming you get a pneumatics design that works for climbing, then you just need to add tanks to ensure you have enough air volume. Our current plan is to have six 41in tanks and the small compressor on-board the robot. We will charge the tanks before a match. The compressor is there to ensure any leaks will not be a problem in the match or while queuing - we don't actually expect it to even come on until we are climbing and consuming gobs of air. The size of our two climbing cylinders far exceeds the ability to reasonably climb with just the compressor itself which is why we need the tanks.