Arduino controlled automatically actuated grill block

[Daox]

No, you're looking at it correctly. The L arm will be pulled backwards when the grill door is open. I'm not too worried about it as it'll be made of something hefty and its lifting a really really light door.

Closing it at speed is a question that I don't have an answer to yet. I don't know how much psi will be building up on the door. I also don't know how much torque the actuators put out, but its not a weak device. I could always add another actuator if need be.

Another concern is keeping it closed at speed. Once the actuator powers down, is the motor and gearing in the actuator enough to hold it there? I'm not sure. Me and Metro were just talking about this actually. There are multiple solutions though. The simplest would probably be to use some magnets to hold it closed.

If all else fails, a sliding door would be the next step.

[tasdrouille]

I'm taking the sliding door route. Since my actuator is a shape memory alloy wire, and I don't intend to keep it energized the whole time, the sliding door seemed like the most workable solution.

[wyatt]

I agree that the door will not want to close at speed. You might be able to hinge it at the center (equal pressure on top and bottom for easier opening), or I wonder if a sliding design would work... he said there is plenty of room...

EDIT: Two of my key points were already made by others while I was making my drawing.

[tasdrouille]

With the sliding door, even if there's an "heavy" lateral load, worst case scenario you mount it on ball bearings and longitudinal load will be irrelevant.

[vtec-e]

How about a rotary type valve. Have your opening as normal but install a length of, say, 4" drain pipe cut in half along its length. Fit some end plates with a pivot hole so the half pipe rotates around its centre. Kind of like a ball valve but with pipe instead. That would overcome the wind pressure opening the door at speed. Not unlike the sliding door so whichever is easier i suppose. Just throwing ideas into the pot!

ollie

[wyatt]

Originally Posted by vtec-e

How about a rotary type valve. Have your opening as normal but install a length of, say, 4" drain pipe cut in half along its length. Fit some end plates with a pivot hole so the half pipe rotates around its centre. Kind of like a ball valve but with pipe instead. That would overcome the wind pressure opening the door at speed. Not unlike the sliding door so whichever is easier i suppose. Just throwing ideas into the pot!

ollie

Exactly what basjoos did with his car... I think he operates his with a lever from inside his cabin, but the rotary idea has been done.

[lunarhighway]

ultimately i think many designs are valid, most of the time it will come down to the design of the existing cooling setup and the restrictions thereoff, and the type of actuator you have.

here's some idea's i've been looking into... in my experience rotateing doors are easier to make than slideing ones, but they require a bit more depth, if you're going for a slideing desing a slotted setup as shown below might have some advantages... especially you'd only have to slide the door a fraction of the full distance to make the same opening...thus an actuator with a fixed throw (like the door lock) can be used to provide more torqe, as the same foce has to move the same load over less distanse.

since i was originally planning to use a small motor and gears proved problematic i figured pulleys could work... at first it may look a little mideval, but i figured that if they could put something like that together 700 years ago with simple hand tools, and make it reliable and strong enough to entrust it with lifting a massive wooden bridge that was one of the main safety features of the castle, i should be able to pull off somethign similar that could move a little coroplast rectangle a few cm's... the idea is that two wires are wound around one axle, propperly spaced and maybe separated by a central plate to pervent tangling. useing a relative thin axle it's also an very easy way to convery the fast spinning motion of a relative weak motor into a slow slideing motion with enough torque to get things done

one wire is already wound around the core while the other is just attached to it.

as the core spins the unwinded wire will wind, provideing pulling foce and the othe wire will unwind..this will pull the door open, and if the direction of the motor is reversed it the other wire will pull.

since there's a wheel or lever at the other end the unwindeing wire will be pulled from that end so there shouldn't be to much slack at any time.

i imagine small pulley or running the wire trough flexible tubes could enable the motion to be reliably transmitted over quite some distance, and around curves...

it could be used for both sliding and rotateing doors and in the case of rotating door they can be stacked on top of each other

although i don't think it uses pulleys, the stacked rotary shutter design is currently used on some bmw models

[Daox]

Finally got my order from moderndevice.com that I ordered on the 15th. I got an arduino duemilanove and a RBBB arduino kit. I'll program and test with the duemilanove, and then transfer the chip over to the RBBB board and run the final tested and true version on that board.

I already have had got my sensor and h-bridge from digikey a while ago, so we're ready to go. Soon, I should be able to get everything wired up with a prototype board and hook up the actuator to see how this is gonna work.

[dcb]

I gotcha, you are going to use the duemilanove to program the chip and swap it.

For development purposes, you can also pop the chip out of the duemilanove, and make a cable to connect its rx and tx and reset and 5v and gnd to the rbbb versions of the same and serial program the chip on the rbbb directly (they should be right next to each other on the rbbb).

Much more expedient for development purposes once you get it set up. If you are like me, you will have to recompile and upload many many times before you are happy with the software.

Sorry, back to aerodynamics and mechanics...

[Daox]

Ohhh, I didn't know you could even do that. Thanks for the tip!