1D inertia attachable on 3-dim. bodies (3D dynamic effects are taken into account)


This information is part of the Modelica Standard Library maintained by the Modelica Association.

This component is used to model the gyroscopic torques exerted by a 1-dim. inertia (so called rotor) on its 3-dim. carrier body. Gyroscopic torques appear, if the vector of the carrier body's angular velocity is not parallel to the vector of the rotor's axis. The axis of rotation of the rotor is defined by the parameter n, which has to be given in the local coordinate system of frame_a. The default animation of this component is shown in the figure below.

model Parts.Rotor1D

This component is a replacement for Modelica.Mechanics.Rotational.Components.Inertia for the case, that a 1-dim.-rotational mechanical system should be attached with a 3-dim. carrier body.

The Boolean parameter exact was introduced due to performance reasons. If exact is set to false, the influence of the carrier body motion on the angular velocity of the rotor is neglected. This influence is usually negligible if the 1-dim.-rotational mechanical system accelerates much faster as the base body (this is, e.g., the case in vehicle powertrains). The essential advantage is that an algebraic loop is removed since then there is only an action on acceleration level from the powertrain to the base body but not vice versa.

Schweiger, Christian ; Otter, Martin: Modelling 3D Mechanical Effects of 1-dim. Powertrains. In: Proceedings of the 3rd International Modelica Conference. Linköping : The Modelica Association and Linköping University, November 3-4, 2003, pp. 149-158

Parameters (8)


Value: true

Type: Boolean

Description: = true, if animation shall be enabled (show rotor as cylinder)


Value: 1

Type: Inertia (kg·m²)

Description: Moment of inertia of rotor around its axis of rotation


Value: {1, 0, 0}

Type: Axis

Description: Axis of rotation resolved in frame_a


Value: zeros(3)

Type: Position[3] (m)

Description: Position vector from origin of frame_a to center of cylinder


Value: 2 * world.defaultJointLength

Type: Distance (m)

Description: Length of cylinder representing the rotor


Value: 2 * world.defaultJointWidth

Type: Distance (m)

Description: Diameter of cylinder representing the rotor


Value: StateSelect.default

Type: StateSelect

Description: Priority to use rotor angle (phi) and rotor speed (w) as states


Value: true

Type: Boolean

Description: = true, if exact calculations; false if influence of bearing on rotor acceleration is neglected to avoid an algebraic loop

Inputs (2)


Default Value: Modelica.Mechanics.MultiBody.Types.Defaults.RodColor

Type: Color

Description: Color of cylinder representing the rotor


Default Value: world.defaultSpecularCoefficient

Type: SpecularCoefficient

Description: Reflection of ambient light (= 0: light is completely absorbed)

Connectors (3)


Type: Flange_a

Description: (left) driving flange (flange axis directed INTO cut plane)


Type: Flange_b

Description: (right) driven flange (flange axis directed OUT OF cut plane)


Type: Frame_a

Description: Frame in which rotor housing is fixed

Components (2)


Type: World


Type: Shape

Used in Components (1)



1D inertia attachable on 3-dim. bodies (3D dynamic effects are taken into account if world.driveTrainMechanics3D=true)