Help please! USB Stepper motor Card

[Akhil Kumar 0]

Hi,

 

Recently purchased the Stepper Motor card from opencockpits. I already have an 8-wire Nema 23 stepper motor (2.1 A to 4.2 A). I have searched everywhere but couldnt find anythin on whether the USB Stepper motor Card supports this stepper motor or not. And if it does how much external supply voltage am i looking at to power the card. Please help me out. I want to use this stepper motor because of the requirement of high torque and speed for a project i m working on. Any help would be much much appreciated.

 

Thank you.

 

Regards,

Akhil Kumar

[allardjd 1,853]

I'm no expert, but looking at Jack's review of the card it says the external power supply may be up to 36V and 1A. Taking the amperage values you've supplied for your motor, it sure looks to me as if it requires more current than the card can supply. You won't get any help to speak of from the USB connection to the computer since that is typically limited to 200 mA.

 

On the face of it, in my opinion what you propose will not work.

 

John

[Aircraft Aviation 2]

Hello Akhil!

 

I have not only checked myself but also consulted with my father. Unfortunately John may be correct.

 

The USBStepper Motors Card is designed for cockpit instruments, displays, etc, etc. High torque motors are designed to be used with cards that are capable of handling a very high current. I mentioned in the review that the Stepper Motor card gets quite hot to the touch supplying less than one ampere (1A). Just imagine what 4 Amps would do to it.

 

What application do you need the motor for? If it's an autothrottle, may I suggest the Opencockpits USBDCMotors Card?

http://www.mutleyshangar.com/reviews/jack/dcm/dcm.htm

[Akhil Kumar 0]

I'm no expert, but looking at Jack's review of the card it says the external power supply may be up to 36V and 1A. Taking the amperage values you've supplied for your motor, it sure looks to me as if it requires more current than the card can supply. You won't get any help to speak of from the USB connection to the computer since that is typically limited to 200 mA.

On the face of it, in my opinion what you propose will not work.

John

 

Hi john,

 

Thanks a lot for your inputs. Yeah i was sure the USB power output is way too low for the stepper motor to work. I was thinking more on the lines of using an external power supply to power the motor. But now i realize that the card cant take it. May be i will go for a 1Amp stepper motor.

 

Thanks a lot for your immediate response. 

 

Regards

Akhil

[Akhil Kumar 0]

Hello Akhil!

 

I have not only checked myself but also consulted with my father. Unfortunately John may be correct.

 

The USBStepper Motors Card is designed for cockpit instruments, displays, etc, etc. High torque motors are designed to be used with cards that are capable of handling a very high current. I mentioned in the review that the Stepper Motor card gets quite hot to the touch supplying less than one ampere (1A). Just imagine what 4 Amps would do to it.

 

What application do you need the motor for? If it's an autothrottle, may I suggest the Opencockpits USBDCMotors Card?

http://www.mutleyshangar.com/reviews/jack/dcm/dcm.htm

 

Hi Jack,

 

Thanks a lot for your reply. Well I am working on a force feedback system to drive a set of rudder pedals. For this I designed a system with two linear rails and a ball screw which connects to the stepper motor. Following is the model.

 

 

As the motor revolves the ball screw displaces which is connected to the two linear rails. The rails are connected to the diamond shaped shaft with two parallel springs which is not shown in the photo above. So as the aircraft in FSX changes in altitude and speed the stepper motor spins to a particular degree as commanded by SIOC. As a result the linear rails move making the springs to stretch and making it hard for the pilot to move the rudder pedals. Hope you understood the design though its operation is not clearly described in the photo.

 

Anyway I realized that the stepper motor I have is too powerful for the Stepper Motor Card. So i thought that i could maybe use a driver which amplifies the current from the card to the stepper motor. As you requested the photos of both the stepper motor and the driver I have are shown below. I could have gone for the DC Motor Card, but since i already have this, I was hoping to put it to good use. Can you please tell me if the driver will do the job of driving the motor. Even though I researched, i am not much of an electronics expert. Thanks a lot again for your help.

 

Driver:

 

[Akhil Kumar 0]

I am sure that the motor is too powerful for the card to handle looking at the current requirements. But just in case I go for a one amp steppe motor, i am not sure if it will serve the purpose especially in terms of speed and sensitivity.

 

[Aircraft Aviation 2]

Hello Akhil,

 

I was not aware that you were planning on using a driver.

 

If this is the case, I believe what you say is perfectly possible. Me and my father had a similar idea for a motion platform; obviously, such a powerful stepper motor could not work with the OC card, so we would have needed to develop a driver.

 

I will ask my father for further confirmation since he is the real electronics expert in the house, but I don't see why it wouldn't work.

 

Jack

 

 

[Akhil Kumar 0]

Hello Akhil,

 

I was not aware that you were planning on using a driver.

 

If this is the case, I believe what you say is perfectly possible. Me and my father had a similar idea for a motion platform; obviously, such a powerful stepper motor could not work with the OC card, so we would have needed to develop a driver.

 

I will ask my father for further confirmation since he is the real electronics expert in the house, but I don't see why it wouldn't work.

 

Jack

 

Yeah jack. I was hoping that it would work. Thanks a lot for approaching your father for help. Also the review and the manual show how to connect a stepper motor to the card but nowhere i could get information on how to link the card to any driver. Please do get back to me regarding his opinion about connecting these two pieces of equipment to the stepper motors card. It would really really be helpful. Thanks a lot for your help on this Jack.

 

Regards,

Akhil

 

[Aircraft Aviation 2]

Hi Akhil,

 

I asked him about the driver idea and he said it work would in terms of current demands, etc, etc.

 

The connections, however, I'm not sure, I'll have to take a look at that. I'm under the impression you want it connecting like this Card -> Driver -> Motor, with the driver acting as an amplification unit?

 

Cheers,

 

Jack

[Aircraft Aviation 2]

Hey Akhil,

 

I asked him again and he says unfortunately that driver won't work with the card.

 

The reason is because the stepper motors card produces its own pulsed output, ready to be connected to a stepper motor. By putting it through that driver, yes, you are amplifying current, but you are, in simple terms, superimposing a second series of pulses onto the signal... As I understand it.

[Akhil Kumar 0]

Hey Akhil,

 

I asked him again and he says unfortunately that driver won't work with the card.

 

The reason is because the stepper motors card produces its own pulsed output, ready to be connected to a stepper motor. By putting it through that driver, yes, you are amplifying current, but you are, in simple terms, superimposing a second series of pulses onto the signal... As I understand it.

 

Hi Jack,

 

Thanks a lot for getting back to me. I have confirmed it with another professor here as well and he said it wouldn't work. So i have decided to go for a smaller stepper motor. Will let you know about any progress. Thanks a lot again for your unconditional help jack.

 

Regards,

Akhil

[Aircraft Aviation 2]

No problems Akhil.

 

Like I said I would probably recommend something like the DC Motors card for this; the stepper motor card really is meant for small instruments.

[Akhil Kumar 0]

HI jack,

 

Its me back again. Luckily I got the Nema high torque stepper motor running with the USB stepper motor card without any overheating. I tried testing it with the motion platform i created and the torque it provides is quite sufficient for my needs. But there is a small problem. I did not connect an optical sensor but instead used a potentiometer because i need position feedback for the motion platform.  When i started sioc and tested it through sioc monitor, it just keeps turning and turning and never stop even after i close SIOC..!!..I didnt get a script ready coz i do not know where i can find information on 'how to monitor the rotation of the motor with changing values in the potentiometer through a script'. Could you help me up with a mock up script which uses potentiometer values (0-255) to give position feedback to the motor.

And why do you think the motor is just turning and turning. Is it because of the absence of an optical sensor?? But because i am using a motion platform and not a chronograph as you mentioned in your review, i opted for the potentiometer. Please help.

 

Thank you.

 

Sincerely,

Akhil Kumar