Difference between revisions of "Setpoint signal"

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Reference signal is a signal that will be used as ''target value'' in control systems. Typical occurrencies of reference signals in GD products are:
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Setpoint (a.k.a reference) signal is a signal that will be used as ''target value'' in control systems. Typical occurrencies of setpoint signals in GD products are:
* Position reference
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* Position setpoint
* Velocity reference
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* Velocity setpoint
* Torque reference
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* Torque setpoint
I.e. position reference value may be "1234" which could mean a target position of 1234 mm in some linear actuator. Or torque reference of 5.0 could mean that motor is asked to produce 5 Nm torque.
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I.e. position setpoint value may be "1234" which could mean a target position of 1234 mm in some linear actuator. Or torque setpoint of 5.0 could mean that motor is asked to produce 5 Nm torque.
==Physical reference signal types==
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==Physical setpoint signal types==
Reference signals may have several representations in real world such as:
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Setpont signals may have several representations in real world such as:
* [[Analog reference]] signal
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* [[Analog setpoint]] signal
 
* [[Pulse and direction]] signals
 
* [[Pulse and direction]] signals
 
* [[PWM]] signal
 
* [[PWM]] signal
 
* Serial communication command
 
* Serial communication command
  
In these cases there will be a conversion between input and output units. For example when using +/-10V reference as velocity reference, the relation betveen input to output types could be 1 Volt per 100 rpm (or any other scale).
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In these cases there will be a conversion between input and output units. For example when using +/-10V as velocity setpoint, the relation between input to output types could be 1 Volt per 100 rpm (or any other scale).
==Reference signal characteristics==
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==Setpoint signal characteristics==
 
{| class="wikitable"
 
{| class="wikitable"
 
|-
 
|-
!  !! [[Analog reference|Analog]] !! [[Pulse and direction|Pulse & dir]] or [[Quadrature]] !! [[PWM]] !! Network
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!  !! [[Analog setpoint|Analog]] !! [[Pulse and direction|Pulse & dir]] or [[Quadrature]] !! [[PWM]] !! Network
 
|-
 
|-
 
| Scale & range || Absolute (limited) || Incremental (infinite) || Absolute (limited) ||  
 
| Scale & range || Absolute (limited) || Incremental (infinite) || Absolute (limited) ||  
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*Incremental (infinite)
 
*Incremental (infinite)
 
|-
 
|-
| Reference uses in motion control || Torque, velocity || Position, velocity || Torque, velocity || Position, torque, velocity, parameters
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| Setpoint uses in motion control || Torque, velocity || Position, velocity || Torque, velocity || Position, torque, velocity, parameters
 
|-
 
|-
 
| Pros  
 
| Pros  
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*High resolution & accuracy
 
*High resolution & accuracy
 
*Reduce wiring
 
*Reduce wiring
*More functions than just reference
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*More functions than just setpoint
 
|-  
 
|-  
 
|Cons
 
|Cons

Revision as of 21:16, 24 June 2013

Setpoint (a.k.a reference) signal is a signal that will be used as target value in control systems. Typical occurrencies of setpoint signals in GD products are:

  • Position setpoint
  • Velocity setpoint
  • Torque setpoint

I.e. position setpoint value may be "1234" which could mean a target position of 1234 mm in some linear actuator. Or torque setpoint of 5.0 could mean that motor is asked to produce 5 Nm torque.

Physical setpoint signal types

Setpont signals may have several representations in real world such as:

In these cases there will be a conversion between input and output units. For example when using +/-10V as velocity setpoint, the relation between input to output types could be 1 Volt per 100 rpm (or any other scale).

Setpoint signal characteristics

Analog Pulse & dir or Quadrature PWM Network
Scale & range Absolute (limited) Incremental (infinite) Absolute (limited)
  • Absolute (near infinite)
  • Incremental (infinite)
Setpoint uses in motion control Torque, velocity Position, velocity Torque, velocity Position, torque, velocity, parameters
Pros
  • Widely used
  • Easy to measure
  • Widely used
  • Exact
  • Noise robust
  • EMI noise robust
  • Precise
  • High resolution & accuracy
  • Reduce wiring
  • More functions than just setpoint
Cons
  • EMI noise sensitive
  • Offset & gain errors
  • Limited resolution at low frequency
  • Need reference zeroing because incremental
  • Various "standards", sometimes incompatible
  • Many standards
  • Usually incompatible with other standards