Position source

Forces the flange to follow the input position.

  • signal
  • translational
  • Modelica Standard Library
  • 2 ports
  • 1 parameter
BlockPosition sourceKindpositionSourceLibraryTranslational

Description

Forces the flange to follow a reference position, supplying whatever force that takes. The reference passes through a second-order critically damped (Bessel) filter with critical frequency f_crit, so the flange has continuous velocity even for a step in s_ref.

Example

End stops and motion sources A sliding mass that hits its stops, a mass pushed into an elastic stop, and masses driven by speed and position sources.

20 sin(πt) NForce sourceMass with stopsPosition (stops)Push 10 NMass 1 kgElastic stopStop at 0.1 mPosition (elastic stop)0.2 m/sSpeed sourceMass 1 kg (speed)Velocity (speed source)0.1 sin(πt) mPosition sourceMass 1 kg (position)Position (position source)
In Gradara, select a Position source block and press F1, then choose Open example. It opens as a new model in My models, ready to run.

Also in this example:ConstantSine waveFixed (translational)MassHard stopMass with stopsForce sourceConstant forceVelocity sourcePosition sensorVelocity sensor

Ports

Inputs 1

  • ss_refsignal · m

    Reference position, in meters.

Conserving terminals 1

  • shaftflangetranslational

    Driven flange.

Parameters

  • Filter frequencyf_crit50 Hz

    ≥ 0

    Critical frequency of the reference filter, in Hz. Must be positive.

Equations

Modelica
ω_c = 2π · f_crit
d²s/dt² = (ω_c · (s_ref − s) − 1.3617 · ds/dt) · ω_c/0.6180, with s = flange.s
Initial: flange.s = s_ref

Implementation

Modelica Standard Library 4.1.0Modelica.Mechanics.Translational.Sources.Position
MSL documentation

Assumptions and limitations

  • Force is unlimited: the source is ideal.

See also

Select a block in Gradara and press F1 to open its page offline.