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control the ttl pulse rate in max for my stepper motor
stepper motor
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05-10-2003 09:19 PM
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I have a stepper motor and when I try to run it using MAX, it would shake sevearly. I think the pulses from MAX is too fast, so I want to know if there is a way in MAX that you can adjust the pulse rate
Amaury
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05-12-2003 07:03 PM
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The pulse rate is the restult of the RPM that you load and the counts per rev which you entered in the first configuration window in MAX. For any RPM your pulse rate in hertz should be 60*RPM*Counts/Rev.
Note that stepper mottors are rather noisy by nature. You may also have some problems with encoder feedback. Try running your setup in open loop.
Best of luck,
Amaury
NI Applications Engineer
Note that stepper mottors are rather noisy by nature. You may also have some problems with encoder feedback. Try running your setup in open loop.
Best of luck,
Amaury
NI Applications Engineer
Buechsenschuetz
Active Participant
03-08-2004 08:07 AM
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In the 'interactive' control panel of the MAX you can also enter speed in steps per second, sometimes this is more convenient than entering a rpm value. Of course, in the axis configuration, you have to indicate the steps per revolution rate of your drive system.
But possible motor shake does not only depend on the step rate. If you set your drive (in most cases this is done by configurating the motor driver unit) to full-step mode almost any stepper motor will run rather shaky. You should set it to a reasonable microstep rate (I would suggest to start with 5 or 10 microsteps per full step), and adjust the steps per revolution rate in MAX accordingly.
Even if you set all these values to their optimum there may be some step rates where the motor w
ill run shaky due to mechanical resonance. It is good practice to check the performance of a stepper motor just in the application, i.e. with the mechanical load applied. Mechanical resonance rather occurs at low rpm rates, for higher rpm rates the inertia of the moving parts may be sufficient to overcome resonance effects.
As mentioned earlier, shake of the motor may also be related to improper encoder settings. If you do not run the motor in the velocity mode, MAX will try to compensate an enventual following error when the motor movement is supposed to be finished. If there is still a following error due to improper encoder settings MAX will run through several sequences of trying to correct the following error which sometimes looks like irregular behaviour of the motor itself.
But possible motor shake does not only depend on the step rate. If you set your drive (in most cases this is done by configurating the motor driver unit) to full-step mode almost any stepper motor will run rather shaky. You should set it to a reasonable microstep rate (I would suggest to start with 5 or 10 microsteps per full step), and adjust the steps per revolution rate in MAX accordingly.
Even if you set all these values to their optimum there may be some step rates where the motor w
ill run shaky due to mechanical resonance. It is good practice to check the performance of a stepper motor just in the application, i.e. with the mechanical load applied. Mechanical resonance rather occurs at low rpm rates, for higher rpm rates the inertia of the moving parts may be sufficient to overcome resonance effects.
As mentioned earlier, shake of the motor may also be related to improper encoder settings. If you do not run the motor in the velocity mode, MAX will try to compensate an enventual following error when the motor movement is supposed to be finished. If there is still a following error due to improper encoder settings MAX will run through several sequences of trying to correct the following error which sometimes looks like irregular behaviour of the motor itself.
