Dynomotion

Group: DynoMotion Message: 8392 From: cristian_atzori Date: 9/25/2013
Subject: Possibly fault Kflop board
Today I connected my Kflop+Kanalog to a servo drive with step+dir inputs for position control.
The drive is well working with other controllers, but I was unable to let it work with Kflop step-dir signals.

Then I checked directly with my oscilloscope (with analogue and digital inputs) to see what kind of square wave was going out from Step output from 0 to 7.
Unfortunately no waves were there, but just a very slight signal, barely measurable, when producing motion from Kmotion.
This weak signal (0,2V) can be seen only on the correct step output so I'm sure to take the measures in the correct place.

I checked every step output on the JP7 and JP5: same result.

The boards were working ok using encoder inputs in Kanalog and DAC outputs when driving analog servo drives (velocity control +10-10V).

I think it's an hardware issue, this is the first time I try step outputs so I never noticed it before.

What should I check? (except configuration, that it's supposed to be ok since I use Config&Flash to produce the code for tests).

Thank you
Group: DynoMotion Message: 8393 From: Tom Kerekes Date: 9/25/2013
Subject: Re: Possibly fault Kflop board
Hi Cristian,

KFLOP's Step/Direction Generators have 2 output drive modes.  "Open Collector" and "LVTTL".  If you are selecting Open Collector mode then the pin will only sink current to ground (much like a switch contact to ground), so unless you apply some external current source to the pin (like with a pull up resistor) you will not see anything with a scope.  You can switch to LVTTL mode which will sink and source current to the pin by adding 8 to the Output Channel Number.  See:

http://dynomotion.com/Help/StepAndDirection/StepAndDir.htm

Could this be your problem?

Regards
TK

Group: DynoMotion Message: 8398 From: cristian_atzori Date: 9/26/2013
Subject: Re: Possibly fault Kflop board

 New measures.

Signals are ok only if I select LVTTL mode (step-dir or wuadrature).

Seems like my oscilloscope and the drives are not likely to "understand" open collector modes.





---In DynoMotion@yahoogroups.com, <dynomotion@yahoogroups.com> wrote:

Today I connected my Kflop+Kanalog to a servo drive with step+dir inputs for position control.
The drive is well working with other controllers, but I was unable to let it work with Kflop step-dir signals.

Then I checked directly with my oscilloscope (with analogue and digital inputs) to see what kind of square wave was going out from Step output from 0 to 7.
Unfortunately no waves were there, but just a very slight signal, barely measurable, when producing motion from Kmotion.
This weak signal (0,2V) can be seen only on the correct step output so I'm sure to take the measures in the correct place.

I checked every step output on the JP7 and JP5: same result.

The boards were working ok using encoder inputs in Kanalog and DAC outputs when driving analog servo drives (velocity control +10-10V).

I think it's an hardware issue, this is the first time I try step outputs so I never noticed it before.

What should I check? (except configuration, that it's supposed to be ok since I use Config&Flash to produce the code for tests).

Thank you
Group: DynoMotion Message: 8399 From: Tom Kerekes Date: 9/26/2013
Subject: Re: Possibly fault Kflop board
Hi Cristian,

(I hope you saw my earlier reply)

Open collector mode works well for drives that have opto couplers with the LED anodes connected in together to +5V.

Your drives are probably different and expecting TTL signals.

Regards
TK


Group: DynoMotion Message: 8400 From: cristian_atzori Date: 9/26/2013
Subject: Re: Possibly fault Kflop board

Yes, I suppose it's all functioning. I used the pullup resistors and now is working.


Sorry for the misleading title then, if you wish feel free to remove the topic.


Thank you



---In dynomotion@yahoogroups.com, <tk@...> wrote:

Hi Cristian,

(I hope you saw my earlier reply)

Open collector mode works well for drives that have opto couplers with the LED anodes connected in together to +5V.

Your drives are probably different and expecting TTL signals.

Regards
TK


Group: DynoMotion Message: 8401 From: cristian_atzori Date: 9/26/2013
Subject: Re: Possibly fault Kflop board
Yes, they expect TTL waves. Now I made it work with output 28 (LVTTL quadrature) and succesfully moved the motor.

Maybe you could give me the clue to configure the closed loop, because when moving a linear encoder (related to input 0, for channel 0) accross the 0 point I only can see a very short quadrature train, just when the position value crosses the Destination one. Short signals only when passing that zero point, and then nothing.

When using the DAC output mode I can see, instead, a constant DC output until Position and Destination are convergent, and that is what I expected to see in step-dir output mode.

Could you please tell me what are the values to modify to have a constant train of quadrature pulses when I move le linear encoder far away from the cross point?

Here is the code I was using:

#include "KMotionDef.h"

// Defines axis 0, 1, 2 as simple step dir outputs
// enables them
// sets them as an xyz coordinate system for GCode

int main()
{
            ch0->InputMode=ENCODER_MODE;
    ch0->OutputMode=CL_STEP_DIR_MODE;
    ch0->Vel=10000;
    ch0->Accel=60;
    ch0->Jerk=600;
    ch0->P=0.3;
    ch0->I=0.005;
    ch0->D=0.1;
    ch0->FFAccel=0.0005;
    ch0->FFVel=0.0005;
    ch0->MaxI=200;
    ch0->MaxErr=10000;
    ch0->MaxOutput=20;
    ch0->DeadBandGain=0.5;
    ch0->DeadBandRange=0;
    ch0->InputChan0=0;
    ch0->InputChan1=0;
    ch0->OutputChan0=28;
    ch0->OutputChan1=0;
    ch0->MasterAxis=-1;
    ch0->LimitSwitchOptions=0x0;
    ch0->InputGain0=1;
    ch0->InputGain1=1;
    ch0->InputOffset0=0;
    ch0->InputOffset1=0;
    ch0->OutputGain=1;
    ch0->OutputOffset=0;
    ch0->SlaveGain=1;
    ch0->BacklashMode=BACKLASH_OFF;
    ch0->BacklashAmount=0;
    ch0->BacklashRate=0;
    ch0->invDistPerCycle=1;
    ch0->Lead=0;
    ch0->MaxFollowingError=100000;
    ch0->StepperAmplitude=20;

    ch0->iir[0].B0=1;
    ch0->iir[0].B1=0;
    ch0->iir[0].B2=0;
    ch0->iir[0].A1=0;
    ch0->iir[0].A2=0;

    ch0->iir[1].B0=1;
    ch0->iir[1].B1=0;
    ch0->iir[1].B2=0;
    ch0->iir[1].A1=0;
    ch0->iir[1].A2=0;

    ch0->iir[2].B0=0.000769;
    ch0->iir[2].B1=0.001538;
    ch0->iir[2].B2=0.000769;
    ch0->iir[2].A1=1.92076;
    ch0->iir[2].A2=-0.923833;



    EnableAxisDest(0,0);
    EnableAxisDest(1,0);
    EnableAxisDest(2,0);

    DefineCoordSystem(0,1,2,-1);

    return 0;
}



Thank you


---In dynomotion@yahoogroups.com, <tk@...> wrote:

Hi Cristian,

(I hope you saw my earlier reply)

Open collector mode works well for drives that have opto couplers with the LED anodes connected in together to +5V.

Your drives are probably different and expecting TTL signals.

Regards
TK


Group: DynoMotion Message: 8402 From: cristian_atzori Date: 9/26/2013
Subject: Re: Possibly fault Kflop board
Ok, I think I got it.
In all your manuals and examples P is set to 0 or very small values, but now I found the system working as it should with P set at least to 50.

The linear encoder reads 1000 pulses/mm, and the motor will have a rotary encoder set to 1000 (read as 4000 from the drive).

Now I can finally see my dual closed loop working, it'll be just a matter of time to calculate the correct PID values using Ziegler-Nichols tables, before final optimization.

Thank you Tom for all the support!


---In dynomotion@yahoogroups.com, <cristian_atzori@...> wrote:

Yes, they expect TTL waves. Now I made it work with output 28 (LVTTL quadrature) and succesfully moved the motor.

Maybe you could give me the clue to configure the closed loop, because when moving a linear encoder (related to input 0, for channel 0) accross the 0 point I only can see a very short quadrature train, just when the position value crosses the Destination one. Short signals only when passing that zero point, and then nothing.

When using the DAC output mode I can see, instead, a constant DC output until Position and Destination are convergent, and that is what I expected to see in step-dir output mode.

Could you please tell me what are the values to modify to have a constant train of quadrature pulses when I move le linear encoder far away from the cross point?

Here is the code I was using:

#include "KMotionDef.h"

// Defines axis 0, 1, 2 as simple step dir outputs
// enables them
// sets them as an xyz coordinate system for GCode

int main()
{
            ch0->InputMode=ENCODER_MODE;
    ch0->OutputMode=CL_STEP_DIR_MODE;
    ch0->Vel=10000;
    ch0->Accel=60;
    ch0->Jerk=600;
    ch0->P=0.3;
    ch0->I=0.005;
    ch0->D=0.1;
    ch0->FFAccel=0.0005;
    ch0->FFVel=0.0005;
    ch0->MaxI=200;
    ch0->MaxErr=10000;
    ch0->MaxOutput=20;
    ch0->DeadBandGain=0.5;
    ch0->DeadBandRange=0;
    ch0->InputChan0=0;
    ch0->InputChan1=0;
    ch0->OutputChan0=28;
    ch0->OutputChan1=0;
    ch0->MasterAxis=-1;
    ch0->LimitSwitchOptions=0x0;
    ch0->InputGain0=1;
    ch0->InputGain1=1;
    ch0->InputOffset0=0;
    ch0->InputOffset1=0;
    ch0->OutputGain=1;
    ch0->OutputOffset=0;
    ch0->SlaveGain=1;
    ch0->BacklashMode=BACKLASH_OFF;
    ch0->BacklashAmount=0;
    ch0->BacklashRate=0;
    ch0->invDistPerCycle=1;
    ch0->Lead=0;
    ch0->MaxFollowingError=100000;
    ch0->StepperAmplitude=20;

    ch0->iir[0].B0=1;
    ch0->iir[0].B1=0;
    ch0->iir[0].B2=0;
    ch0->iir[0].A1=0;
    ch0->iir[0].A2=0;

    ch0->iir[1].B0=1;
    ch0->iir[1].B1=0;
    ch0->iir[1].B2=0;
    ch0->iir[1].A1=0;
    ch0->iir[1].A2=0;

    ch0->iir[2].B0=0.000769;
    ch0->iir[2].B1=0.001538;
    ch0->iir[2].B2=0.000769;
    ch0->iir[2].A1=1.92076;
    ch0->iir[2].A2=-0.923833;



    EnableAxisDest(0,0);
    EnableAxisDest(1,0);
    EnableAxisDest(2,0);

    DefineCoordSystem(0,1,2,-1);

    return 0;
}



Thank you


---In dynomotion@yahoogroups.com, <tk@...> wrote:

Hi Cristian,

(I hope you saw my earlier reply)

Open collector mode works well for drives that have opto couplers with the LED anodes connected in together to +5V.

Your drives are probably different and expecting TTL signals.

Regards
TK


Group: DynoMotion Message: 8403 From: Tom Kerekes Date: 9/26/2013
Subject: Re: Possibly fault Kflop board
Hi Cristian,

I don't really understand that.  You should start off with P=0.  With CL Step/Direction mode the "Output" is a Position Offset (not a velocity or torque/acceleration like in a typical servo).  Normally I Gain is used to ramp the Output Offset at a rate proportional to error.

You should match the linear encoder resolution to the Step Pulse resolution by changing the InputGain0 setting.  This way CL Step/Direction Feed Forward will cause the output to follow the Input Trajectory without any feedback (PID=0,0,0).

The Settings in your previous email had a MaxOutput=20.  This limits the feedback correction offset to only +/-20 Steps.  That is why you only saw a few output pulses when the error switch direction.

You should set FFAccel and FFVel to zero.

Hope this helps.
Regards
TK


Group: DynoMotion Message: 8404 From: cristian_atzori Date: 9/27/2013
Subject: Re: Possibly fault Kflop board

Yes  Tom, I realized what MaxOutput is related to. The fact is that I was testing the linear encoder by hand, not connected in any mechanical way to the motor.

The rotary encoder has variable resolution (internal dip switches), I'll then try to find the best way to make the system close the loop even with PID 0,0,0.

Isn't it better to change rotary resolution in order to increase Output Gain instead of Input?




---In dynomotion@yahoogroups.com, <tk@...> wrote:

Hi Cristian,

I don't really understand that.  You should start off with P=0.  With CL Step/Direction mode the "Output" is a Position Offset (not a velocity or torque/acceleration like in a typical servo).  Normally I Gain is used to ramp the Output Offset at a rate proportional to error.

You should match the linear encoder resolution to the Step Pulse resolution by changing the InputGain0 setting.  This way CL Step/Direction Feed Forward will cause the output to follow the Input Trajectory without any feedback (PID=0,0,0).

The Settings in your previous email had a MaxOutput=20.  This limits the feedback correction offset to only +/-20 Steps.  That is why you only saw a few output pulses when the error switch direction.

You should set FFAccel and FFVel to zero.

Hope this helps.
Regards
TK