Setpoint signal

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Revision as of 14:32, 27 March 2012 by 130.230.150.205 (Talk) (Physical reference signal types)


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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:

  • Position reference
  • Veloicty reference
  • Torque reference

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.

Physical reference signal types

Reference 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 reference as velocity reference, the relation betveen input to output types could be 1 Volt per 100 rpm (or any other scale).

Reference signal characteristics

Analog Pulse & dir PWM Serial
Scale Absolute Incremental Absolute Absolute & incremental possible
Reference uses in motion control Torque, velocity Position, velocity Torque, velocity Position, torque, velocity
Pros
  • Widely used
  • Easy to measure
  • Widely used
  • Exact
  • Noise robust
  • EMI noise robust
  • Precise
  • High resolution & accuracy
  • Reduce wiring
  • More functions than just reference
Cons
  • EMI noise sensitive
  • Offset & gain errors
  • Limited resolution at low frequency
  • Various "standards", sometimes incompatible
  • Many standards
  • Mostly incompatible with each other

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