Hello,

I am 37-year-old emerging artists looking for some help with a project I have. There's a sculpture I would like to construct part of the sculpture is using small motors to turn a series of squares. Think of a checkerboard and each square would be able to turn on its own in a random pattern but on certain times of the day all the squares would move back into their original positions.

There is more to the sculpture than that but this is the basic idea I am having trouble with. I have been doing my best to discover what I need to do from the research I've done I guess I would have to use something called stepper motors, a microcontroller obviously some type of circuit board design and learn something called program “C” code language?

As much as I'm trying to do my best to grasp this new form of expression I am at a loss I do not have the aptitude or training to understand all the nuances that go into creating the complex piece of machinery that I desire. So I was wondering is there anyone out there that can give me a hand with this?


I live in Southern California although I am not a real artist yet I hope to be one someday there's nothing worse than having an idea knowing what you want but not knowing how to make it come to life. So if anyone out there can point me in the right direction offer some help give some suggestions or I may even be able to pay somebody I just need a little guidance.

Thank you for your time

Sincerely,

The artist that needs help!!!

 

I would take a look at the Arduino, a microcontroller development platform. They were developed specifically for artists and other people unfamiliar with microcontrollers and programming. http://www.arduino.cc/en/Guide/Introduction

 

Do the squares turn in 90degree increments ?

 

The Arduino or the basic stamp from www.parallax.com. Basic is probably an easier language to learn first. Your code is not going to be the hard part. But the hardware is. I asume that you are going to control several motors and you may run out of outputs.
You also are going to have to build or buy a motor driver.
You can check these documents and always can back to us for help. http://www.bipom.com/documents/appnotes/an8_motors-1.pdf
http://www.st.com/stonline/books/pdf/docs/13709.pdf
You also may be able to use some gear mechanism to control several cubes to save outputs somehow.
Also if you live in Southern California you can check "All Electronics" is an electronics surplus store located in the San Fernando Valley. where you can find the cheapest parts. I will suggest you to just buy one small servo motor that the uC (micro controller) can control without a driver and experiment with it first. The output current capability of uCs are very small. You can also try to see if Nitinol wires can be of some help. I see Nitinol wires a more elegant solution, you can check them at www.nitinol.com. Parallax is in your area you may call them to see what they recomend you, make sure you tell them how may cubes you want to control and how heavy. I think the propeller chip has quite a lot of outputs.
By the way I think your idea is really cool a sculpture that changes like that. Powering it by solar cells would be even better. You should pattent an idea like that.

 

Google "wooden mirror"

Ken

 

What will be the dimensions and weight of the blocks that you wish to animate?

One of the first things you should do is build yourself a power supply. I suggest converting an ATX-form-factor power supply to a bench supply; you can get a supply from a discarded PC. This is pretty easy to do and quite inexpensive.
Google "ATX Bench Supply" and read through several of the sites to get ideas.

There are several types of stepper motors; the two main types are bipolar and unipolar.
Bipolar are difficult for a hobbyiest to work with.
Unipolar steppers are much easier.
Here is a good (and inexpensive) one for a beginner to experiment with:
http://www.jameco.com/webapp/wcs/st...toreId=10001&catalogId=10001&productId=171601
The specification is for 7v, but they'll run just fine on 5v.
Oh, they're 7.5° per step instead of 3.6 degrees. 48 full steps per complete rotation, or 96 (3.75°/step) if you half-step them.

As far as drivers, I suggest starting off with a ULN2803A IC, which is Eight Darlington Drivers in a single DIP IC. Mouser.com has decent prices on the ST Microelectronics version:
http://www.mouser.com/Search/ProductDetail.aspx?qs=FOlmdCx%2bAA1lVc/YEXA4pg==
$0.60/each if you buy 10.
One of these ICs can drive up to two of those stepper motors.

As far as microcontrollers go, you can spend a lot or a little.
Parallax Inc. Basic Stamps are pretty easy to use, are programmed in a BASIC-like langage, but they are expen$ive and S-L-O-W.

I have no experience with Arduinos.

PIC uCs (microcontrollers) are made by Microchip Inc. They are far faster and far less expensive than Basic Stamps. They can be programmed in a BASIC-like language that's similar to the Parallax Basic Stamps, but the Basic compiler is extra.

You can get started with PIC uCs pretty inexpensively. The hard part is deciding which PIC uC to get - they have quite a wide selection!

[eta]
Here's a page on MicroChip's website that has several Application Notes on using PIC uC's for controlling stepper motors:
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1515

 

It would be useful to have a bit more information - How many squares?, what angle of rotation is required?, what is the axis of rotation? do all pieces move at the same time?

Based on the information given, you could use an inexpensive Microchip 8-pin PIC per motor (either stepper or servo depending on requirements) and each would run the same simple code turning the motor to random positions at intervals. A synchronise input linking each module would force them all to return to their starting positions upon receiving an external trigger.

This modular approach would keep the software and hardware very simple as well as being relatively inexpensive.

 

The Arduino would be a great place to start. The programming environment is
very easy to use and there is a large helpful user community. There are a lot
of artist users.

I have been working on integrating wireless communication with an
Arduino. Some of my stuff is at www.wiblocks.com

(* jcl *)

 

Wow!


This feedback is great! Thank you so much for all your help I will do my best to answer some of the questions that have been put forth to me.

• The measurement of my sculpture is roughly 36" x 40.25" thickness is yet to be determined depending on what is needed with circuit boards motors etc.
• The squares measure 2" x 2" with an 8 inch gap between each square. There are a total of about 326 squares
• The weight of each square would be determine on how heavy a load the stepper motor or servos could withstand
• Each square would rotate 90° left or right in a random pattern
• Before the square would turn every other square would have to rise above the square next to it in order for it to make its revolution so if you imagine a red and black checkerboard imagine all the black squares have risen about a half-inch above the board before they start to turn once they've made the 90° revolution in whatever direction was chosen the squares retract back down to the board and the Red Squares would follow the same process.

Thank you once again for all your help I really do appreciate it this is so cool this is really what the Internet was made for in my opinion I can't thank you guys enough for taking the time out of your day to help a perfect stranger all advice is welcome I am new to this but I'm trying to do my best to make sense of everything that was proposed to me

Thank you so much


Sincerely

The artists who need help

 

I will suggest that you check this other forum called "Embeded Systems and Microcontrollers" and ask specific questions there that you may encounter as you go alone that forum has more info. refering to your application. It is a few lines below this General Electronics Chat.

 

[*]The measurement of my sculpture is roughly 36" x 40.25" thickness is yet to be determined depending on what is needed with circuit boards motors etc.

Pretty large piece!
Just to give you an idea of the size of the stepper motors I suggested you try, the mounting "ears" on the same model that I have measure just shy of 2" at their extreme ends, the can portion is just under 1.4" in diameter and 0.585" deep. The shaft protrudes 0.54" from the front face and about 0.39" from the rear face, making the total depth 1.52".

[*]The squares measure 2" x 2" with an 8 inch gap between each square. There are a total of about 326 squares

OK, if you made the squares out of a reasonably lightweight material, and didn't try to change their rotational speed very rapidly, that should be quite do-able.

[*]The weight of each square would be determine on how heavy a load the stepper motor or servos could withstand

I'm afraid it's the other way around, unless you're willing to spend a bloody fortune on stepper motors. The little stepper motors I suggested only have about 2.55 in/oz of torque when run on their full voltage, which isn't a lot. However, you could make the blocks from aircraft grade spruce, which would be very strong, durable and quite lightweight - and very attractive if stained rather than painted. You could go with balsa, which would be even lighter, but rather fragile and easily dented. I suggested these motors because they are small, inexpensive, and don't use much power. You could go with more powerful units, but that would complicate your drive and power requirements enormously, and costs would spiral upwards at a truly discouraging rate.

[*]Each square would rotate 90° left or right in a random pattern

OK, for precision alignment, you'll need a sensor that will report when the block is at 0°, 90°, 180°, or 270°. That could be accomplished reasonably easily using a LED illuminator and light detector pair with a slotted interrupter ring attached to the stepper's shaft. You'll need some kind of positive feedback anyway, as it's possible for steppers to "skip a beat" now and then. It will become mandatory when recovering from a power failure, unless you like having to manually re-align 384 wood blocks every time SoCalEd sneezes.

[*]Before the square would turn every other square would have to rise above the square next to it in order for it to make its revolution so if you imagine a red and black checkerboard imagine all the black squares have risen about a half-inch above the board before they start to turn once they've made the 90° revolution in whatever direction was chosen the squares retract back down to the board and the Red Squares would follow the same process.
[/LIST]

The last is going to be the real trick. Cost is always a factor, as is reliability. You're going to need a separate actuator to move the stepper motor/block combination outwards before beginning the turn of the block. Moving the stepper motor implies flexing of it's wiring harness, which will eventually lead to metal fatigue, and subsequent failing of the motor to operate. OTOH, the older versions of this stepper (like I have) have a 10-tooth brass gear roughly 0.4" long. It may be possible to use the gear as 1/2 the mesh in a spline arrangement, keeping the stepper motor stationary, but using a fork (like a clutch throwout in an automotive application) to extend the block outwards. I have no clue where you might find a mating female spline for a reasonable cost, however. It's just a concept.

 

I don't understand the dimensions, this part in particular:
"The squares measure 2" x 2" with an 8 inch gap between each square"

When you say 2" you mean 2 inch?

 

Hi everyone,

Thanks again for the help any suggestions on which direction I should start?


And to clarify the squares of the sculpture would be 2" x 2" with 1/8 inch gap between them

Thank again for the help

Sincerely

The artists that needs help

 

Thanks again for the help any suggestions on which direction I should start?

What is your budget for the electronics? You need to establish that right away.

What is your time frame in which you hope to complete this project?

Do you have any programming skills?

I suggest that you start off by ordering 10 of those stepper motors and 10 of the ULN2803 IC's I mentioned in my first reply; at least you will have some of the basic components to work with, with a minimal investment. At those quantities, you'll get a decent discount. If you should happen to make a number of mistakes and burn things up, you will have spares on hand.

Then I suggest you look into building that ATX bench supply. You will need some basic tools to do that, like solder, soldering iron, solder flux, 91% isopropyl alcohol, pliers, wire cutters, drills and bits, etc.

You're going to need all of this stuff no matter which uC you wind up getting.

Then you need to start making a decision as to which uC you might go with. That can be complex.

 

From the description it sounds like half of the squares rise and turn at the same time i.e on a chequer board all the black squares rise, turn 90 degrees then retract. Is this correct?

For turning the squares, I think RC servos might be worth considering since they are easy to interface with just 1 wire (no extra drive hardware), torquey, and move to an absolute position - you won't need to add extra position sensing. They're also very cheap now. On the down side, RC servos don't usually rotate 360 degrees so you might need to gear-up (not by much) to get full rotation.

Another advantage of using servos is that if you don't require control of individual motors you can connect them in groups controlled from a single output. So, you could divide the 300+ servos into 8 groups and control each group from a single output pin of just one 8-bit port. You would need to add extra buffers to drive a large numbers of servos but these are just off-the-shelf chips. If you think that using 300+ stepper motors, each requiring 4 outputs and 1 input, could become complex from a hardware and i/o perspective, consider the reality of wiring them all up !!!

As for the square rising action: You could mount all the red square servos on a sheet of plywood(A) which would have holes cut in place of the missing black squares. On another piece of plywood(B) attach all the black square servos, but spaced a couple of inches above the board. When board A is placed on B the black square servos would protrude through the holes in board A completing the matrix. Devise a motorised mechanism that allows the boards to slide back and forth in relation to each other, this will allow one set of squares to rise above the others before rotating. To prevent the mayhem that might occur if any squares were to rotate when not raised you could fit switches to the boards so that the servos only receive power when the squares are in the raised position.

 

Here is my response to your questions thanks again for the help

J



What is your budget for the electronics? You need to establish that right away.

Not that I have all the money in the world but I think I'll be okay of course I would like to make it as cheap as possible

What is your time frame in which you hope to complete this project?
My timeframe is open

Do you have any programming skills?
Unfortunately I do not have any programming skills .


I suggest that you start off by ordering 10 of those stepper motors and 10 of the ULN2803 IC's I mentioned in my first reply; at least you will have some of the basic components to work with, with a minimal investment. At those quantities, you'll get a decent discount. If you should happen to make a number of mistakes and burn things up, you will have spares on hand.

Then I suggest you look into building that ATX bench supply. You will need some basic tools to do that, like solder, soldering iron, solder flux, 91% isopropyl alcohol, pliers, wire cutters, drills and bits, etc.
I have all the tools I need to make this
You're going to need all of this stuff no matter which uC you wind up getting.

Then you need to start making a decision as to which uC you might go with. That can be complex.

Unfortunately I do not understand the term”uC” could you please elaborate

Do you know if there are any premade microcontroller boards where all I would have to do is interface with the computer to program the chip?

A.N.H.

 

uC means Microcontroller u is micro in Engineering notacion. As I told you to make things less complicated you should try with the basic stamp from Parallax.com buy a board of education that already has a conection to connect a servo motor. Parallax has a lot of programs examples in BASIC which is the easiest programming language to learn you can then modify the programs to fit your application. Parallax is also close to you call them they will help you.
I think after you experiment with it for a while you will know what you need.
Forget about driver circuits and power supplies for now or it will overwhelm you.

 

The Board of Education full USB kit comes with a Basic Stamp 2 and some jumper wires; it requires a power supply to run it. $129. There is a serial port version for $99, but they're almost out of stock.
Their Parallax (Futaba) Continuous Rotation Servo is out of stock, won't ship until 7/22.
The servos are $12.95 each. At that rate, you'll have over $4,500 invested in just servos - or $4,000 more than the stepper motors I'd suggested, if you're buying them in quantities > 100.

Servo motors will require a minimum of 3 wires; power, ground, and signal.
Stepper motors will require a minimum of 4 wires if they're run in bipolar mode, 5 if run unipolar. Both the Parallax servomotor and the stepper motors I suggested have wiring harnesses that can plug in to a board designed to receive the connector.

Servo motors require "nulling" to get their home (starting) position stable. Sometimes it's necessary to readjust them. They may make clicking noises when they're sitting there idle.

Stepper motors will require a feedback method so that the home position can be found. If they are not turning, they will not make any sounds at all. If they are running in half-step mode, they may emit a low growl related to the speed they're running.

MicroChip's PICkit 1 runs about $35; it comes with a programming suite and documentation on disk, and a PIC12F675 uC. The PICkit programming board is powered by your USB port. It has a break-away project board that you populate with components that you supply. The PIC12F675 would be difficult to use for an application as complex as yours, but it would be enough to control a single stepper motor using a driver IC. The PICkit 1 does not program their complete line of uC's; just the more basic to midrange 8 and 14 pin versions. There is a signal analysis daughterboard you can add for another $25 for additional functionality and troubleshooting capabilities.

The PICkit 2 programs their midrange line of uC's. $49. I don't have one, but I bought Myke Predko's book, "Programming and Customizing PICmicro Microcontrollers", 2nd Edition. It runs $35, but I bought it via a seller on Amazon for less. It comes with Myke's "El Cheapo" PIC programmer board that programs most of Microchip's 8, 14, 18, 28 and 40 pin uC's.
Here's Myke's page on his book (it's a big book)
http://www.myke.com/pic-book.htm

This is a pretty large project you have in mind. It's going to be quite complex by the time you have it completed. Start with something simple; just getting a single motor to spin at a controlled rate will be a big accomplishment from where you're sitting now.

Try experimenting with a few different types of microcontrollers, and a few different types of motors. It may be a bit bewildering at first. If you find yourself getting frustrated or tired, walk away for a while and do something else.

 

The Board of Education full USB kit comes with a Basic Stamp 2 and some jumper wires; it requires a power supply to run it.

The board of education also run on a 9V. battery.
You can find a board of education an a BS2 (basic stamp two) on eBay for arround $60.
http://cgi.ebay.com/Parallax-Basic-...oryZ4663QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
The stepper motor in www.allelectronics.com start at $1.50. Parallax does sells more expensive their parts than other vendors. As I told you go to Allelectronics they are in the San Fernado Valley.
I do recomend steppers motors for the project however to start learning I recomend a servo motor. Buy it wherever is cheaper. Parrallax has a lot of learning material free in pdf. With a pic uC you will need more money to start and will need to get a breadbord too the compiler program and do some soldering, not with the BS so that is why a recomended the BS for a start. Besides Parallax has better one on one support than Pic Microchip. I did not mean buy things from Parallax buy things wherever you want. As a note I did some projects with the BS2 for over one year and I never bought a thing from them. Shop around if your time is worth saving a few dollars.

 

The board of education also run on a 9V. battery.

That is true. However, the moment our OP attempts to connect a stepper motor or servo to it, he's either going to need a LOT of batteries, or a power supply.

You can find a board of education an a BS2 (basic stamp two) on eBay for arround $60.
http://cgi.ebay.com/Parallax-Basic-...oryZ4663QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

True, but as our OP is a relative newcomer to electronics and robotics, I was attempting to guide him to well-known sources. Ebay has less than a perfect track record.

The stepper motor in www.allelectronics.com start at $1.50

I see that. Unfortunately, there is no datasheet available for that particular Epson stepper motor, nor could I find one with a quick search of my usual sources. They DO have a somewhat smaller motor similar to the one I mentioned earlier, but they're selling them at $3/ea. One very important consideration is how easy will it be to get the entire complement of motors that the OP requires? Once Alltronics runs out of their inventory, and if he doesn't have enough, he will either have to find more of the same motors elsewhere, or change his design to accomodate other motors.

The particular motors I pointed out earlier, PF35T-48L4, have been made by a number of manufacturers. There are a LOT of them out there, somewhere. Jameco apparently has a bunch of them.

Parallax does sells more expensive their parts than other vendors. As I told you go to Allelectronics they are in the San Fernado Valley.

That might be quite a hike for the OP. The big problem is, he won't have access to the board here while he's shopping, to ask questions about what might be a good thing for him and what's not. It could seem like a rather bewildering experience.

I do recomend steppers motors for the project however to start learning I recomend a servo motor. Buy it wherever is cheaper.

I'm afraid I don't see your logic. While they are indeed both motors that can be controlled via a uC, the methods used to control the two types is completely different, as you must surely know. Parallax's servos are modified so that they can freely rotate. If he purchased a servo elsewhere, it would not have that modification. Servos require a 1 to 2 mS pulse every 20mS; the best way to handle that is via interrupts. Basic Stamps are slow, and don't have interrupts (except for the BS2p24/40 I think), so controlling a servomotor using a Basic Stamp would be a real chore. Besides which, if he is eventually going to be using stepper motors, very little of the code he writes for servomotors will be applicable.

Parrallax has a lot of learning material free in pdf.

True. MicroChip has several magnitudes more free learning material and documentation on their website.

With a pic uC you will need more money to start and will need to get a breadbord too the compiler program and do some soldering, not with the BS so that is why a recomended the BS for a start.

Basic Stamp starting costs: $99 minimum for a BoE, serial interface. Better get the USB model for $129, as your next computer won't have RS232.
PIC uC starting costs: $35, (PICkit 1) USB compatible (and powered)
Has 8 LEDs on board to show the states of the pins. You can easily add 4 more. Has a header for interfacing to the $25 Signal Analysis board and/or a breadboard. You can pick up a breadboard from your local Radio Shack for under $15.

Now if you want to program a PIC in the same BASIC language used in Parallax's Basic Stamp 1, the compiler is $99. If you want the same language as the Basic Stamp 2, the compiler is $249. However, the PICkit 1 comes with free versions of C and Assembler, and an integrated programming environment. The big difference is that Basic Stamps (BS2sx) run at up to 50kHz, while PIC uC's start at 4MHz. Right out of the box, the slowest PIC uC is 80x as fast as the fastest Basic Stamp.

Besides Parallax has better one on one support than Pic Microchip.

They did have a pretty active forum several years ago; I haven't checked in lately. Microchip has a large (and rapidly growing) user's group. If the OP was going for a small project, a Basic Stamp would probably be fine. However, with this large of a project, he's going to need to use a rather large number of uC's, and they're all going to have to talk to each other. A Basic Stamp just won't be fast enough, and it'll be really expensive.

I did not mean buy things from Parallax buy things wherever you want. As a note I did some projects with the BS2 for over one year and I never bought a thing from them. Shop around if your time is worth saving a few dollars.

I have a BoE (serial) and a couple of Basic Stamps (BS2e, BS2sx) sitting next to me that I've had for about a decade. Parallax is still selling practically the exact same products today, although I see they've recently added a line they call "SX". The Javelin is fairly new, along with the Propellor.

But really, Parallax is geared for the education and hobbyist market. Microchip is geared for hobbyists to professionals.

The PIC12 line is so inexpensive that the OP could have two PIC uP's on every stepper motor for what a dozen BS2p40's would cost him - and he sure wouldn't be able to get the job done with a dozen BS2p40s.