Editing Signal path of motor drive

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===Setpoint signal path===
 
===Setpoint signal path===
 
Main parts are:
 
Main parts are:
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*Input multiplier. Purpose of this is to increase resolution of input setpoint to allow more fine grained velocity & acceleration control in trajectory planner. By default {{param|MUL}} value is 50.
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*Input multiplier. Purpose of this is to increase resolution of input setpoint to allow more fine grained velocity & acceleration control in trajectory planner. By default [[MUL]] value is 50.
 
*Setpoint smoothing filter. If enabled, applies low pass filter to signal reducing jitter and roughness of signal but also introduces about some delay. By default the filter has 100% attenuation at 250Hz.
 
*Setpoint smoothing filter. If enabled, applies low pass filter to signal reducing jitter and roughness of signal but also introduces about some delay. By default the filter has 100% attenuation at 250Hz.
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*[[Trajectory planner]]. This limits rate of change of setpoint signal based on {{param|CVL}} and {{param|CAL}} parameters. Output rate maximum rate of change:
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*Trajectory planner. This limits rate of change of setpoint signal based on [[CVL]] and [[CAL]] parameters. Output rate maximum rate of change:
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**Velocity changes max {{param|CAL}} nubmer of units per [[control cycle]] (control cycle is 400µs in most GD drives)
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**Velocity changes max [[CAL]] nubmer of units per [[control cycle]] (control cycle is 400µs in most GD drives)
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**Velocity maximum value is limited to {{param|CVL}}
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**Velocity maximum value is limited to [[CVL]]
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*Input divider. This divides setpoint signal by {{param|DIV}} to give desired output scale for ''internal setpoint''. Combination of multiplier and divider can be used change total scaling of setpoint signal.
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*Input divider. This divides setpoint signal by [[DIV]] to give desired output scale for ''internal setpoint''. Combination of multiplier and divider can be used change total scaling of setpoint signal.
  
  
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* Velocity mode: frequency input, setpoint = number of edges of either channel per [[control cycle]]
 
* Velocity mode: frequency input, setpoint = number of edges of either channel per [[control cycle]]
 
|-
 
|-
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| PWM || rowspan="2" |Absolute || Full input scale equals setpoint range of +/-16384. In loss of PWM signal, setpoint is 0. || rowspan="3" |
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| PWM || rowspan=2 |Absolute || Full input scale equals setpoint range of +/-16384. In loss of PWM signal, setpoint is 0. || rowspan=3 |
 
*Direct 1:1 absolute value in position mode
 
*Direct 1:1 absolute value in position mode
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*Velocity & torque mode: +/-16384 represents full torque or speed scale
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*Velocity & torque mode: +/-16834 represents full torque or speed scale
 
|-
 
|-
 
| Analog || Full input scale equals setpoint range of +/-16384  
 
| Analog || Full input scale equals setpoint range of +/-16384  
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|}
 
|}
  
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It should be noted that trajectory planner operates after multiplier meaning that {{param|CVL}} velocity limit value is not in equal scale with velocity setpoint value.
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It should be noted that trajectory planner operates after multiplier meaning that [[CVL]] velocity limit value is not in equal scale with velocity setpoint value.
  
 
===Internal setpoint===
 
===Internal setpoint===
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*Position mode: position sensor [[Quadrature|counter]] raw value
 
*Position mode: position sensor [[Quadrature|counter]] raw value
 
*Velocity mode: internal goes through '''Velocity normalized''' that changes scales depending on setpoint source:
 
*Velocity mode: internal goes through '''Velocity normalized''' that changes scales depending on setpoint source:
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**In PWM & Analog source: Internal setpoint of +/-16384 represents whole speed range covered by {{param|CVL}} parameter. I.e. 10V input to analog input runs motor at 100% speed and -5V at -50% etc.
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**In PWM & Analog source: Internal setpoint of +/-16384 represents whole speed range covered by [[CVL]] parameter. I.e. 10V input to analog input runs motor at 100% speed and -5V at -50% etc.
 
**In all other sources: number of feedback device [[Quadrature|counts]] per one [[control cycle]]. Obtained by calculating the difference of position feedback values at every control cycle.
 
**In all other sources: number of feedback device [[Quadrature|counts]] per one [[control cycle]]. Obtained by calculating the difference of position feedback values at every control cycle.
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*Torque mode: '''Torque normalizer''' scales internal setpoint so that value of +/-16384 represents full torque scale (i.e. internal setpoint value 16384 outputs configured peak current {{param|MMC}} and 8192 outputs {{param|MMC}}/2)
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*Torque mode: '''Torque normalizer''' scales internal setpoint so that value of +/-16384 represents full torque scale (i.e. internal setpoint value 16384 outputs configured peak current [[MMC]] and 8192 outputs [[MMC]]/2)
  
 
==Controller==
 
==Controller==
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[[File:Driveblockdiagram controller.png|898x898px]]
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[[File:Driveblockdiagram controller.png|800px]]
  
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<nowiki>*</nowiki>) Update rates may be drive model specific. 2500 Hz and 20 kHz apply for most drives including IONI and ATOMI. However, torque control domain on ARGON is 17500 Hz.
 
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==Calculation formulas and examples==
 
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These examples focus on calculating values on a rotary motor and linear axis.
 
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===Constants used later in calculations===
 
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Assuming control cycle to be 400µs / 2500 Hz (default in GD drives):
 
  
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<math>f=2500</math>
 
  
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Calculation of how many counts the [[feedback devices|feedback device]] produces per one physical unit:
 
  
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<math>X_{FeedbackDeviceCountsPerUnit}=4\frac{P_{FBR}}{P_{AXS}}</math>
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==Setpoint scale examples==
 +
Assuming control cycle to be 400µs / 2500 Hz (default in GD drives).
  
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AXS is a number that tells how many physical lenght units (such as millimeters a linear axis) translates per one rotary motor revolution.
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===Example 1===
 +
;Calculating setpoint
 +
*Motor has 2500 P/R encoder (10000 CPR) and user wants to rotate it at 1000 rpm in velocity mode. Scaling is set to 1:1 (MUL/DIV ratio is 1)
 +
*Rotation speed is 1000/60 = 16.667 revs/s (RPS) Needed encoder count frequency is 16.667*10000 = 16667 counts/s.
 +
*Internal setpoint is the amount of counts per control cycle so in this case it's 16667/2500 = 66.667
  
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===Example 1 - Calculating setpoint in position mode===
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Because set point is integer value user must round setpoint to 66 or 67. To achieve exact speed, he could change input scaling (MUL/DIV) to allow unrounded value here.
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Here we convert physical units (such as millimeters) to setpoint value in position control mode:
+
  
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<math>setpoint=\frac{P_{MUL}}{P_{DIV}}*D_{DesiredPosition}*X_{FeedbackDeviceCountsPerUnit}</math>
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;Calculating acceleration and velocity limits
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If DIV is 50, then user must have [[CVL]] value at least 3333 (66.6667*50).
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===Example 2 - Calculating value for CVL parameter===
+
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Here we convert speed (such as mm/sec, or whatever lenght units AXS represents) to {{param|CVL}} value:
+
−
 
+
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<math>P_{CVL}=\frac{V_{DesiredSpeedLimit}*X_{FeedbackDeviceCountsPerUnit}*P_{DIV}}{f}</math>
+
−
 
+
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===Example 3 - Calculating value for CAL parameter===
+
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Here we convert speed (such as mm/sec<sup>2</sup>, or whatever lenght units AXS represents) to {{param|CAL}} value:
+
−
 
+
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<math>P_{CAL}=\frac{A_{DesiredAccelerationLimit}*X_{FeedbackDeviceCountsPerUnit}*P_{DIV}}{f^2}</math>
+
−
 
+
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In alternative method we don't need acceleration value, but just time <math>t</math> in seconds to define how long motor should take to accelerate from zero speed to maximum speed defined by CAL:
+
−
 
+
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<math>P_{CAL}=\frac{P_{CVL}}{tf}</math>
+
  
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If user wants motor to accelerate to 1000 rpm in 0.1 seconds, then [[CAL]] is value should be 3333/2500/0.1 = 13.33. Value must be again rounded to integer and rounding error could be reduced by adjusting scaling (adjust DIV).
 
{{tip|Granity calculates real world units thus it can be used to calculate and experiment with the scales. As scales are linear, interpolation of values is viable choice.}}
 
{{tip|Granity calculates real world units thus it can be used to calculate and experiment with the scales. As scales are linear, interpolation of values is viable choice.}}
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==See also==
 
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*[[Trajectory planner]]
 
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[[Category:Development]]
 
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[[Category:Glossary]]
 
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[[Category:Argon_user_guide]]
 

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