Help with a setup

Guest, I just read a thread on Globalspec the other day about a new product that can be inserted in a motor controler and alows for it to be accesed, monitord and altered through a cell phone from anyplace you have acess. This may save some time on R&D. Check the past 2 or 3 days on Globalspec, I to will check and post if I find it. J.Conway

i'm actually not really interested in that type of controller. I'll be controlling the setup from a laptop and program with C#. I believe i need a motor, encoder, and controller but I'm not sure which ones will be compatible with each other or will be appropriate for my project.

Guest, I know what your second post said but since I had stated I would follow up with this I am posting the link incase anyone following this thread is interested. http://www.abb.us/cawp/seitp202/2dd234daf5cc338285257519004db1f8.aspx. Best of luck with your project. J.Conway

Hello Guest

I previously performed a projet similar to yours when I was a student on ODTU too. I can give you some tips.

First, if you will drive your motor form a computer, you will need a receiving circuitry on motor driver side. you will need a microprocessor or a smart device. My advice is to use a microcontroller (such as PIC16F877A which is very popular on student projects and very cheap.) This microcontroller shall have a serial interface (USART is very popular) to communicate with your computer.

Secondly: your notebook uses 12 V for logic "1" on serial port, but microprocessor or microcontrollers use 5 VDC. You will need a logic level coupler. the most popular one is MAX232. this IC couples the 12 V logic high of PC with 5 V logic high of microcontrollers.

Both PIC and MAX 232 datasheets will teach you many thing.

Third: the stepper motor issue. the step angle may be decreased with two methods. first is to use micro driving. miicro driving may be performed via the micrcocontroller. my advice is to use a second method. choose a stepper motor with a gear box. many kinds of gear boxes are available on the market. some are with plastic gears and some with steel. gear boxes can minimize the step angle and increase the total torque delivered to the load. but willl increase the power that system dissipate.

Another very important issue: if you use gear boxes with your motor, the motor will stopimmediately when you stop the power, and so you will not need a feedback line, and of course the encoder will not be needed. this can decrease your cost.

Lastly: the microcontroller output can be used with stepper motor driver ICs. this ICs are very usefull but a very common problem occurs, the ICs can stand only to 1 amps of current. and when you realy want to move something 1 amps is not enough. If you need big electric power to be delivered to the stepper motors, dont use driver ICS but use power transistors suc as TIP41 or 40 as amplifiers. (very cheap and common :) )

as a motor use a six pin (2 pins for supply voltage, 4 pins for driving), 8 pin motors are harder to driev since driver ICs for 8 pin are not common on market . If you are lucky and have money, maybe you can find a motor with step angle lesser then 1 degree, so you wont need the gear box or microdriving. If you dont want to use gear boxes or microdriving, please see Kumar's electromechanical energy conversion book's stepper motor chapter.

Summarizing the system that I advice you :

Laptop RS232 port --> Max232 --> PIC16F877A --> Amplifiers with power transistors.

many amplifier designs are available on web and its a very common and easy job. dont fear the amplifier side.

If you have any problem on circuitry side I can mail it to you. but as a student it will be better that you perform it yourself.

and one last point: there are many freeware porgramming interfeaces for PIC microcontrollers on web, you can use MPLabs free IDes etc... But you can not use C# on PIC programming, you will need to use the old c :).

I hope I could help you.

Hello Avionics:

Hope you are well?.........I think you may well have more input to this thread. But what you have done so far is worth a GA to you!

Take care, and happy new year..........

If you can't make it happen with C use Basic. I use the parralel port. It's as simple as writing and receiving numbers to and from the port.

Yes, Parallel port and basic are good choices too. serial port has some advantages and disadvantages for me;

first of all: most of the new commercial notebooks does not include a serial port. the mass prodcution commercial computer companies generally prefered to eliminate the serial port for preventing the home build application development on last 5 years. there are some USB to serial converters, I tried a few of them but none of them are efficient. and there has been many years that I did not use the parallel port. the concern is existence; which one exist on the laptop of the guest.

secondly If you dont want too write an interface software for your computer to send the data to the motor driver, you can simply send the data from the "hyperlink" tool of windows. Just tune the baud rate and parity bit, write the data and click enter, easy. a good advantage of serial port.

thirdly: I dont know to program in basic language :)

I will try to see if I have time to send some driver circuitry, which can be very helpful. even some pic.c or micro.c codes whom are previously used by me with micrcontrollers, I want to send but this is a matter of time. I will try.

and some ICs which are previously been tried and found successfull, I can advice too.

Lastly: thank you for your kindness babybear :)

happy new year to you all too

Stepping motor 101.

Unlike many other motors, all stepping motors require driver electronics to control the 2, 3, 4, or 5 phase stator field. (This driver is not a C subroutine that ports data from one format to another.) Some manufacturers incorporate this driver inside the motor chassis ( http://www.imshome.com/ ) some sell separate external drivers and some leave it up to designer to locate suitable electronics. So as far as your C# program and laptop is concerned, its the choice of driver electronics that define your coding. Some primitive drivers take just simple bit control of step and direction to step the motor. (Faster step pulse means faster motion.) Some intelligent motor drivers can be talked to with RS232, RS422, Ethernet and even some newer wireless communication. These more intelligent drivers get configured to handle many parameters that your laptop would no longer have to contend with like acceleration rate and curve, peak rotational velocity, running power and idle power and where is the rotor shaft now. Some intelligent motors integrate a built in encoder to operate the motor in a closed loop fashion. Most of these drivers require an external DC power supply to provide power for the motor. This is one of the few times that an unregulated power supply is actually preferred.

I use the less intelligent motors from the company web page above. They make fully intelligent drivers and ones that take simple step and direction bit signals. They also build motors with integrated encoders of varying resolution but I don't think that they do a closed loop mode. You will likely need to do quadrature decoding of the encoder signal to determine position.

Since you will be specifically doing antenna testing I strongly suggest you use a motor with a built in driver. The chopper electronics that permit micro-stepping movement can produce significant EMI. Putting the driver electronics inside the motor chassis means the smallest loop antenna to transfer the harmonic energy into free space.

Hi Redfred,

I am a mech engr trying to get familiar with machine and motion control.

I will be thankful for guidnace about reading material etc on this subject and clearing possible doubts.

How can i message u private . my email....ssujeer@yahoo.com

Jooka

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