RelativeVelocity

Measure relative velocity vector between the origins of two frame connectors

Diagram

Information

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

The relative velocity vector between the origins of frame_a and of frame_b are determined and provided at the output signal connector v_rel. This vector is defined as:

r_rel = MultiBody.Frames.resolve2(frame_a.R, frame_b.r_0 - frame_a.r_0);
v_rel = der(r_rel);

Via parameter resolveInFrame it is defined, in which frame the velocity vector is resolved:

resolveInFrame =
Types.ResolveInFrameAB.
Meaning
world Resolve vector in world frame
frame_a Resolve vector in frame_a
frame_b Resolve vector in frame_b
frame_resolve Resolve vector in frame_resolve

If resolveInFrame = Types.ResolveInFrameAB.frame_resolve, the conditional connector "frame_resolve" is enabled and v_rel is resolved in the frame, to which frame_resolve is connected. Note, if this connector is enabled, it must be connected.

Example

If resolveInFrame = Types.ResolveInFrameAB.frame_b, the output vector is computed as:

r_rel   = MultiBody.Frames.resolve2(frame_a.R, frame_b.r_0 - frame_a.r_0);
v_rel_a = der(r_rel);
v_rel   = MultiBody.Frames.resolveRelative(frame_a.R, frame_b.R, v_rel_a);

Parameters (1)

resolveInFrame

Value: Modelica.Mechanics.MultiBody.Types.ResolveInFrameAB.frame_a

Type: ResolveInFrameAB

Description: Frame in which output vector v_rel shall be resolved (world, frame_a, frame_b, or frame_resolve)

Connectors (4)

frame_a

Type: Frame_a

Description: Coordinate system a

frame_b

Type: Frame_b

Description: Coordinate system b

v_rel

Type: RealOutput[3]

Description: Relative velocity vector resolved in frame defined by resolveInFrame

frame_resolve

Type: Frame_resolve

Description: Coordinate system in which v_rel is optionally resolved

Components (4)

relativePosition

Type: RelativePosition

zeroPosition

Type: ZeroPosition

der_r_rel

Type: Der[3]

transformRelativeVector

Type: TransformRelativeVector