Difference between revisions of "Setpoint signal"

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(Reference signal characteristics)
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Revision as of 21:14, 24 June 2013

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
  • Velocity 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 or Quadrature PWM Network
Scale & range Absolute (limited) Incremental (infinite) Absolute (limited)
  • Absolute (near infinite)
  • Incremental (infinite)
Reference uses in motion control Torque, velocity Position, velocity Torque, velocity Position, torque, velocity, parameters
  • Widely used
  • Easy to measure
  • Widely used
  • Exact
  • Noise robust
  • EMI noise robust
  • Precise
  • High resolution & accuracy
  • Reduce wiring
  • More functions than just reference
  • 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