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Setpoint signal

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An example setpoint signal (target value) and measured response signal (realized output value) of a control system.

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[edit | edit source]

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[edit | edit source]

Analog Pulse & dir or Quadrature PWM Serial / 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

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