Dynomotion

Group: DynoMotion Message: 14818 From: Tom Kerekes Date: 5/27/2017
Subject: Re: Help with setting up Glass Scales with Kflop & SnapAmp & Stepper
Hi Andy,

Adjust the InputGain0 parameter to match the linear encoder resolution to the motor cycles resolution.  "Counts" per inch in KMotionCNC shouldn't change as that is actually based on motor cycles. To calculate the value we would need to know your mechanics: pulley ratios, lead screw pitch, etc.   You will know when you have the correct value when the Position and Command match on a large open loop move on the Step response screen within expected mechanical tolerances. 

HTH
TK

On May 26, 2017, at 10:44 PM, andysontag@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

 

Hi Tom,


I searched around and couldn't find any examples of setting up a kflop / snapamp / stepper combo with glass scale encoders. I've installed glass scales on our machine and would like to use them instead of the rotary encoders we have been using thus far. 


The glass scales have a resolution of 5 um and a quadrature output that is connected to the differential encoder inputs on the snapamp. I'm assuming each edge of the quadrature is equal to 5 um. With the rotary encoders we used 50 / (4 * encoder PPR) to calculate the input gain and then adjusted the counts per inch until the travel distance matched up. With glass scales it seems like the calculation will need to be done a bit differently. Could you provide some guidance on how to calculate the input gain and counts per inch?


Andy
Group: DynoMotion Message: 14829 From: andysontag Date: 5/30/2017
Subject: Re: Help with setting up Glass Scales with Kflop & SnapAmp & Stepper
Thanks Tom. The tip about matching up the position and command in the step response screen was key. 

I ended up setting the input gain to .005, the "Counts" per inch in KMotionCNC to 25.4, and I adjusted the Inv Dist Per Cycle until the position and command matched up in the step response screen. This way command is done with millimeters instead of cycles. This seems to work well, but let me know if it isn't advisable. 

Andy
Group: DynoMotion Message: 14830 From: Tom Kerekes Date: 5/31/2017
Subject: Re: Help with setting up Glass Scales with Kflop & SnapAmp & Stepper

Hi Andy,

That sounds reasonable to me.

Regards

TK


On 5/30/2017 7:46 PM, andysontag@... [DynoMotion] wrote:
 

Thanks Tom. The tip about matching up the position and command in the step response screen was key. 


I ended up setting the input gain to .005, the "Counts" per inch in KMotionCNC to 25.4, and I adjusted the Inv Dist Per Cycle until the position and command matched up in the step response screen. This way command is done with millimeters instead of cycles. This seems to work well, but let me know if it isn't advisable. 

Andy