Opinions on this idea

[grrr_arrghh]

Hi.

I am easily frustrated by this whole electronics lark, so decided to set myself a long term goal. I came up with this idea, I wondered if a few people could give me their opinons.

A very large CD changer (500 cds or more). The rack that the cds are in is horizontal, with the cds sticking up vertically. In the middle of the rack are two slot loading cd players. A robot travels along the rack, picking out cds and placing them into one of the cd players. It woudn't matter if this took a while, as with two cd players, one can be playing, while the other is loading/unloading.

A playlist is loaded onto a computer, it looks at its database and works out which cd the track is on. It then gives the robot instructions (prob through serial) telling it to move a certain distance/no. of axel rotations/whatever. When the robot gets to this position, it runs a sub-program (sub-sequence? I can't remeber what you call them) which controlls some servos to make an arm move to pick up the cd. It then covers the distance in the oposite direction, and places the cd in the slot loading cd drive. The computer would then select the right track, and play it. After the track has finished, the other cd player would start playing (all controlled by the computer), and the robot would retrieve the cd from the player and return it to the storage rack, using much the same method as it did to fetch the cd in the first place.

Couple of problems (apart from my complete lack of programming knowledge...!) are how would the robot move? It needs to be accurate, to get the right cd, and not thin air. I'm thinking the ideal would a converyor belt type setup, so that the robot was moved, rather than having to move itself. However, I worry that if the conveyor belt stretched or warped or whatever, the robot could end up in the wrong place. So I think maybe a sort of rack and pinion system, with each cd being a certain number of teeth apart, so the robot only has to do a full number of rotations of an axal (how the hell do you spell that?).

What does everyone think? Is it feasible? Any suggestions? Do you like it? Dislike it?

I'm not intending to make it soon, I just wondered what everyone thought.

Yeah, i know, it would be easier to load all the tracks onto an mp3 player (which I have done), but thats not quite in the spirit of hobyist electronics...

Cheers,

Tim

 

[Nigel Goodwin]

It's certainly possible, just a question of money and time really!.

However, why not just buy a multi-CD player? - Sony make one that holds 300 CD's, and does pretty well what you want - and they are pretty cheap as well!.

The CD's are slotted vertically into a turntable, the turntable turns round setting each CD slot in exactly the correct position for moving into the CD mech - this avoids your 'robot arm' worries :lol:

 

[panic mode]

It's more than doable but i'm not sure it is justified considering
progress in electronics and falling prices. If you want to do it as
an excercise that's fine, just keep in mind that in few years
the whole thing could be available as cheap chewgum sized device
with plenty of flash storage and all bells and whistles.

 

[grrr_arrghh]

However, why not just buy a multi-CD player? - Sony make one that holds 300 CD's, and does pretty well what you want - and they are pretty cheap as well!.

If you want to do it as
an excercise that's fine, just keep in mind that in few years
the whole thing could be available as cheap chewgum sized device
with plenty of flash storage and all bells and whistles.

Yeah, it was just as an exercise, to challenge myself - as I mentioned, it would be much easier to load the whole lot onto an mp3 player

The CD's are slotted vertically into a turntable, the turntable turns round setting each CD slot in exactly the correct position for moving into the CD mech - this avoids your 'robot arm' worries :lol:

I quite like that idea - the only prob being that if I wanted to add capacity for extra CDs, I would have to completly re-built the thing, whereas with a long rack, i could add extra rack to the end. And anyway, robot arms look cool! at least in my world...

Thanks for the feedback guys.

Tim

 

[pittuck]

Why not get into micromouse its a lot harder than it looks u know... And there are lots of people who have done it/similar things to help u out.

 

[grrr_arrghh]

micromouse

whats that?

 

[pittuck]

:shock:

Ok, imagin a robot that goes around a 16x16 grid maze. Each cell is 18cm square and the walls are 1.2cm wide and 5cm high.

The aim is to get from the starting square (lower left corner) to the middle in the shortest amount of time.

You have 10 minutes to do your best. In this you can search through the maze as long as you like mapping the maze. Then you can make up to 3 runs, the fastest run is recorded and the mouse with the fastest run wins.

Lots more info here:

**broken link removed**

 

[stevez]

What you have described was actually built/sold on a larger scale to governments and other entities for mass storage/access to large volumes of data. I was involved in this in the late 80's/early 90s. As far as I know the cost/mb was competitive at the time but that edge disappeared just as the product made it to market.

 

[grrr_arrghh]

What you have described was actually built/sold on a larger scale to governments and other entities for mass storage/access to large volumes of data

Great minds think alike... :lol:

I have seen the racks used by TV companies (probably not used anymore, since the advent of digital), in which tapes were stored in big vertical racks, with the tapes stored horizontally, and robots travelled up and down the rack to retrieve certain tapes, when they needed to be aired.

I was thinking maybe i could put a bit of fur on the arm, so it looks like a bear?!? Maybe i'm just too sad.

Cheers.

Tim

 

[bmcculla]

Look at a lead screw to move the robot back and forth.

This seems more like a mechanical engineering problem than an electronics problem. The electronics should be fairly easy.

 

[captainkirksdog]

Hi Tim!
Maybe you could use a barcode/reader at each CD location. The robot could travel inside three rails, grab the correct CD with a vacuum clamp, and return. You'd need a database for lookup/location tables, some kind of feedback system, error routines, etc. I think it would be fun!

BTW, the largest robot retrieval system I have personally used was for after-hours/weekend dry storage of boats. You accessed the system with an ATM-like card, punched in your request, and a REALLY BIG FORKLIFT went and got your boat. It could retrieve or stow from as high up as 60 feet. It would put your boat in a cradle near the water which you could then launch from. It traveled on rails instead of tires and could handle boats up to 40 foot long. At twenty-five bucks a pop, I only watched it twice.

 

[samcheetah]

why do u want to use CDs at all. u know DVDs have more capacities and BlueRay is in for debut this year. CDs (and simillar media) are prone to scratches. so why dont u use a large array of hard drives. like 100 of them connected in a RAID configuration. that would be probably more efficient because the read/write speeds of hard drives are greater than that of CDs. most university servers have a large number of disk drives connected in this way. u can also use SCSI drives for high performance.

so why go for a technology that is to be outdated sooner or later????

 

[grrr_arrghh]

why do u want to use CDs at all. u know DVDs have more capacities and BlueRay is in for debut this year. CDs (and simillar media) are prone to scratches. so why dont u use a large array of hard drives. like 100 of them connected in a RAID configuration. that would be probably more efficient because the read/write speeds of hard drives are greater than that of CDs. most university servers have a large number of disk drives connected in this way. u can also use SCSI drives for high performance.

so why go for a technology that is to be outdated sooner or later????

As I have explained (or tried to) in earlier posts, this is simply a project for something to build, rather than a solution to a problem.

Thanks for the suggestions anyway

 

[samcheetah]

As I have explained (or tried to) in earlier posts, this is simply a project for something to build, rather than a solution to a problem.

Thanks for the suggestions anyway

okay i get it. well what u have set for yourself is really expensive and time consuming and there is a chance that it might not work as u need it to because of the complexity. anyway good luck

 

[grrr_arrghh]

anyway good luck

Thankyou

 

[elfvenlord]

Sounds like a great idea grrr but I reckon it would be much easier to use a turntable instead of a rack.That way the turntable can rotate and your robotic arm can stay in one place.Maybe you could have the layout so that your CD players and arm are in the midle of the turntable 8)
Check out the diagram below!

 

[grrr_arrghh]

that would make it a lot easier. And i like the diagram.

Again though, i'm attracted to the challenge of my method. Trying to do something in the hardest possible way...

It'll be a while til i get round to it, so i'll have plenty of time to get round to the sensible way of doing things.

Thanks for ALL the suggestions, I really appreciated them.