RelativeVelocity
Measure relative velocity vector between the origins of two frame connectors
Library
Modelica/Mechanics/MultiBody/Sensors
Description
The relative velocity vector between the origins of frame_a and of frame_b aredetermined 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 framethe 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, towhich frame_resolve is connected. Note, if this connector is enabled, it mustbe connected.
Example
If resolveInFrame = Types.ResolveInFrameAB.frame_b, the output vector iscomputed 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
| Name | Label | Description | Data Type | Valid Values |
|---|---|---|---|---|
mo_resolveInFrame | resolveInFrame | Frame in which output vector v_rel shall be resolved (world, frame_a, frame_b, or frame_resolve) | Structure | |
mo_resolveInFrame/choice1 | Resolve in world frame | Number | 0 | |
mo_resolveInFrame/choice2 | Resolve in frame_a | Number | 0 | |
mo_resolveInFrame/choice3 | Resolve in frame_b | Number | 0 | |
mo_resolveInFrame/choice4 | Resolve in frame_resolve (frame_resolve must be connected) | Number | 0 |
| Name | Label | Description | Data Type | Valid Values |
|---|---|---|---|---|
mo__nmodifiers | Number of Modifiers | Specifies the number of modifiers | Number | |
mo__modifiers | Modifiers | Add new modifier | Structure | |
mo__modifiers/varname | Variable name | Cell of strings | ||
mo__modifiers/attribute | Attribute | Cell of strings | 'start' | |
mo__modifiers/value | Value |
Ports
| Name | Type | Description | IO Type | Number |
|---|---|---|---|---|
frame_a | implicit | Coordinate system a | input | 1 |
frame_b | implicit | Coordinate system b | output | 1 |
v_rel | implicit | Relative velocity vector resolved in frame defined by resolveInFrame | output | 2 |
Port 4 | implicit | Coordinate system in which v_rel is optionally resolved | output | mo_resolveInFrame.choice4 |