modelRelativeStates

Definition of relative state variables

Extends from Interfaces.OnePort (OnePort partial model of rotational library).

Information

Usually, the absolute angle and the absolute angular velocity of Modelica.Mechanics.Rotational.Inertia models are used as state variables. In some circumstances, relative quantities are better suited, e.g., because it may be easier to supply initial values. In such cases, model RelativeStates allows the definition of state variables in the following way:

  • Connect an instance of this model between two flange connectors.
  • The relative rotation angle and the relative angular velocity between the two connectors are used as state variables.

An example is given in the next figure

Here, the relative angle and the relative angular velocity between the two inertias are used as state variables. Additionally, the simulator selects either the absolute angle and absolute angular velocity of model inertia1 or of model inertia2 as state variables.

Release Notes:

Connectors

TypeNameDefaultDescription
Flange_aflange_a (from OnePort)Left rotational connector
Flange_bflange_b (from OnePort)Right rotational connector

Components

TypeNameDefaultDescription
Modelica.SIunits.Anglephi_relRelative angle used as state variable
Modelica.SIunits.AngularVelocityw_relRelative angular velocity used as state variable
Modelica.SIunits.AngularAccelerationa_relRelative angular acceleration