Dynomotion

Group: DynoMotion Message: 1712 From: quelisto Date: 8/19/2011
Subject: Questions on axes configuration
Hello again Tom. My question is somewhat general: if one configures an
axis for something other than a stepper, what will the resultant signal
"look" like? For example, if I configure an axis to be a brushed motor
axis, will the output continue to be a step and direction pair, or is it
a direct PWM signal and a direction bit? I ask because Gecko makes a
brushed controller that uses step and direction information, and I'm not
sure whether this is considered the "standard" way of doing things
regarding the inputs to an amplifier.

Also, does the type of axis output affect the number of axes available
(i.e. is it always 8?).

Thanks!
Group: DynoMotion Message: 1713 From: Tom Kerekes Date: 8/19/2011
Subject: Re: Questions on axes configuration
Hi Quelisto,
 
There are two fundamental approaches that can be used.  You must first decide whether you wish to let KFLOP close the position servo loop or let the Amplifier close the servo loop.
 
Geckos are designed to close the servo loop themselves.  In this case KFLOP is "out of the loop" and would be configured to just output Step/Dir.  From KFLOPs viewpoint the system would be open loop exactly like a stepper.  Encoder feedback would go to the Amplifier rather than KFLOP (or optionally both if you would like KFLOP to monitor the Encoder position).  How well the servo loop performs would be dictated by tuning in the Gecko (several pots).
 
The alternate approach is for KFLOP to close the position loop.  The most common way to do this is to add a Kanalog board to output +/- 10V analog commands to some type of 3rd party servo motor amplifier.  The encoder feedback must be connected to Kanalog or KFLOP.   In this case the output mode would be configured as DAC Servo.  Usually the amplifier is configured to control the velocity commanded by KFLOP/Kanalog.  KFLOP will then dictate the servo performance with its PID gains, Filters, etc...
 
Another way for KFLOP to close the position loop is by using a SnapAmp.  SnapAmp supports several motor types including DC Brushless motors.  But basically Current commands are sent digitally to SnapAmp.
 
You can mix/match motor types as long as you can make the necessary motor/amplifier connections up to 8 axes.
 
Regards
TK
 
 
 
 
 
 
 
 

--- On Fri, 8/19/11, quelisto <quelisto@...> wrote:

From: quelisto <quelisto@...>
Subject: [DynoMotion] Questions on axes configuration
To: DynoMotion@yahoogroups.com
Date: Friday, August 19, 2011, 8:26 PM

 

Hello again Tom. My question is somewhat general: if one configures an
axis for something other than a stepper, what will the resultant signal
"look" like? For example, if I configure an axis to be a brushed motor
axis, will the output continue to be a step and direction pair, or is it
a direct PWM signal and a direction bit? I ask because Gecko makes a
brushed controller that uses step and direction information, and I'm not
sure whether this is considered the "standard" way of doing things
regarding the inputs to an amplifier.

Also, does the type of axis output affect the number of axes available
(i.e. is it always 8?).

Thanks!