Hi Tom,

Just started working again on an earlier project where you helped me with operating brushless servo motors in torque mode.

During the testing the axis disengage and then re-engage within about 1/2 second. It does happen as the loading increases on the servos. I suspect it is because something has reached it's limit and resets. There is no message on the console screen, so I was hoping you could suggest a reason this reset action may be occurring. Perhaps then I could add some print statements to narrow down the culprit.

The system is KFlop with SnapAmp controlling a 2 axis slide.

Thanks for your help,

David.

Hi David,

When the peak current limit on SnapAmp is exceeded SnapAmp will disabled for about that long.  The "fault" LED on SnapAmp should come on for that period.

What are you setting the Peak Currents to?  Is the LED blinking?

Regards
TK

 

Hi Tom,

Just started working again on an earlier project where you helped me with operating brushless servo motors in torque mode.

During the testing the axis disengage and then re-engage within about 1/2 second. It does happen as the loading increases on the servos. I suspect it is because something has reached it's limit and resets. There is no message on the console screen, so I was hoping you could suggest a reason this reset action may be occurring. Perhaps then I could add some print statements to narrow down the culprit.

The system is KFlop with SnapAmp controlling a 2 axis slide.

Thanks for your help,

David.

Hi Tom,

The peak limits are set at "WriteSnapAmp(SNAP0+SNAP_PEAK_CUR_LIMIT1,12);" (both axis set the same) and the MaxOutput is set at 150. I will have to check on the LED to see it's status during the fault.

Do the Max Limits (output, integrator, error) come into play here? I don't really understand how they affect the servo action.

Thank you,
David.

 

Hi David,

When the peak current limit on SnapAmp is exceeded SnapAmp will disabled for about that long.  The "fault" LED on SnapAmp should come on for that period.

What are you setting the Peak Currents to?  Is the LED blinking?

Regards
TK

On 4/8/2016 12:47 PM, david.m.stevenson@... [DynoMotion] wrote:

 

Hi Tom,

Just started working again on an earlier project where you helped me with operating brushless servo motors in torque mode.

During the testing the axis disengage and then re-engage within about 1/2 second. It does happen as the loading increases on the servos. I suspect it is because something has reached it's limit and resets. There is no message on the console screen, so I was hoping you could suggest a reason this reset action may be occurring. Perhaps then I could add some print statements to narrow down the culprit.

The system is KFlop with SnapAmp controlling a 2 axis slide.

Thanks for your help,

David.

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Hi Tom,

I increased the peak current limits and that seemed to cure the disengage/re-engage issue.

With this setup I use the gampad to move the slide, but because the torque has been limited the following error grows which causes a lurching of the slide when the commanded direction changes and there is no longer a torque load to deal with.

Is it possible to use a line of code such as "ch0->Position = ch0->Dest;" which would run every 0.1 seconds to remove any built up following error, or some other method to reset the gamepad's lead?

Thanks,
David.

Hi David,

I don't think that would work.  It might help with the jerk but then your encoder position would be wrong.

You might be able to adjust your servo tuning parameters so it comes out of saturation more gracefully.  Such as reducing the Max Error and Max Integrator values.  In that way even though the following error would grow to a huge value the servo would only "see" a small error.

Regards
TK

 

Hi Tom,

I increased the peak current limits and that seemed to cure the disengage/re-engage issue.

With this setup I use the gampad to move the slide, but because the torque has been limited the following error grows which causes a lurching of the slide when the commanded direction changes and there is no longer a torque load to deal with.

Is it possible to use a line of code such as "ch0->Position = ch0->Dest;" which would run every 0.1 seconds to remove any built up following error, or some other method to reset the gamepad's lead?

Thanks,
David.

Hi Tom,

Just to confirm... the Dest is the encoder position and the Position is the requested location, no?

I will experiment with the error and integrator settings. Could you tell me what units those are in? Are they counts?

Thanks,
David.

 

Hi David,

I don't think that would work.  It might help with the jerk but then your encoder position would be wrong.

You might be able to adjust your servo tuning parameters so it comes out of saturation more gracefully.  Such as reducing the Max Error and Max Integrator values.  In that way even though the following error would grow to a huge value the servo would only "see" a small error.

Regards
TK

On 4/21/2016 5:10 PM, david.m.stevenson@... [DynoMotion] wrote:

 

Hi Tom,

I increased the peak current limits and that seemed to cure the disengage/re-engage issue.

With this setup I use the gampad to move the slide, but because the torque has been limited the following error grows which causes a lurching of the slide when the commanded direction changes and there is no longer a torque load to deal with.

Is it possible to use a line of code such as "ch0->Position = ch0->Dest;" which would run every 0.1 seconds to remove any built up following error, or some other method to reset the gamepad's lead?

Thanks,
David.

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Hi David,

No.  Position is the current encoder position.  Dest is the desired destination to be at.

If you attempt to change the Dest while a motion (Jog or otherwise) is in progress it will immediately be overwritten on the next 90us Servo sample.

Regards
TK

 

Hi Tom,

Just to confirm... the Dest is the encoder position and the Position is the requested location, no?

I will experiment with the error and integrator settings. Could you tell me what units those are in? Are they counts?

Thanks,
David.

On 4/21/2016 8:56 PM, Tom Kerekes tk@... [DynoMotion] wrote:

 

Hi David,

I don't think that would work.  It might help with the jerk but then your encoder position would be wrong.

You might be able to adjust your servo tuning parameters so it comes out of saturation more gracefully.  Such as reducing the Max Error and Max Integrator values.  In that way even though the following error would grow to a huge value the servo would only "see" a small error.

Regards
TK

On 4/21/2016 5:10 PM, david.m.stevenson@... [DynoMotion] wrote:

 

Hi Tom,

I increased the peak current limits and that seemed to cure the disengage/re-engage issue.

With this setup I use the gampad to move the slide, but because the torque has been limited the following error grows which causes a lurching of the slide when the commanded direction changes and there is no longer a torque load to deal with.

Is it possible to use a line of code such as "ch0->Position = ch0->Dest;" which would run every 0.1 seconds to remove any built up following error, or some other method to reset the gamepad's lead?

Thanks,
David.

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Hi Tom,

Thanks for clarifying that. Scary that I've had that bass-ackwards for a few years now.

How about "ch0->Dest 0 ch->0Position;" or is there any other way to zero out the headstart the gamepad stick has built up while the axis couldn't move?

I did try adjusting the integrator and max error today but the results weren't encouraging.

Thank you,
David.

 

Hi David,

No.  Position is the current encoder position.  Dest is the desired destination to be at.

If you attempt to change the Dest while a motion (Jog or otherwise) is in progress it will immediately be overwritten on the next 90us Servo sample.

Regards
TK

On 4/21/2016 6:11 PM, David Stevenson david.m.stevenson@... [DynoMotion] wrote:

 

Hi Tom,

Just to confirm... the Dest is the encoder position and the Position is the requested location, no?

I will experiment with the error and integrator settings. Could you tell me what units those are in? Are they counts?

Thanks,
David.

On 4/21/2016 8:56 PM, Tom Kerekes tk@... [DynoMotion] wrote:

 

Hi David,

I don't think that would work.  It might help with the jerk but then your encoder position would be wrong.

You might be able to adjust your servo tuning parameters so it comes out of saturation more gracefully.  Such as reducing the Max Error and Max Integrator values.  In that way even though the following error would grow to a huge value the servo would only "see" a small error.

Regards
TK

On 4/21/2016 5:10 PM, david.m.stevenson@... [DynoMotion] wrote:

 

Hi Tom,

I increased the peak current limits and that seemed to cure the disengage/re-engage issue.

With this setup I use the gampad to move the slide, but because the torque has been limited the following error grows which causes a lurching of the slide when the commanded direction changes and there is no longer a torque load to deal with.

Is it possible to use a line of code such as "ch0->Position = ch0->Dest;" which would run every 0.1 seconds to remove any built up following error, or some other method to reset the gamepad's lead?

Thanks,
David.

Virus-free. www.avast.com

Virus-free. www.avast.com