LIBRARY

RelativeVelocity

Measures the relative velocity between the origins of two frame connectors.

Always differentiates the relative position resolved in FrameA first, then rotates the result into resolve_in_frame – matching Modelica's RelativeVelocity. Note this differs from RelativeSensor's v_rel output, which differentiates in whatever resolve_in_frame is set to.

This is a sensor: no forces or torques are exerted.

Usage

MultibodyComponents.RelativeVelocity()

Parameters:

Name	Description	Units	Default value
resolve_in_frame		–	ResolveInFrame.FrameA()

Connectors

• frame_a - Frame3D is the fundamental 3D connector used for 6DOF motion. Most components have one or several Frame

connectors that can be connected together (Frame3D)

• frame_b - Frame3D is the fundamental 3D connector used for 6DOF motion. Most components have one or several Frame

connectors that can be connected together (Frame3D)

• frame_resolve - Frame3D is the fundamental 3D connector used for 6DOF motion. Most components have one or several Frame

connectors that can be connected together (Frame3D)

• v_rel_x - This connector represents a real signal as an output from a component (RealOutput)

• v_rel_y - This connector represents a real signal as an output from a component (RealOutput)

• v_rel_z - This connector represents a real signal as an output from a component (RealOutput)

Variables

Name	Description	Units
r_rel_a	Relative position, resolved in frame_a	m
v_rel_a	Relative velocity, resolved in frame_a	m/s
v_rel		m/s

Behavior

Dict{MIME{Symbol("text/plain")}, String} with 1 entry: MIME type text/plain => "Error displaying result"

Source

"""
Measures the relative velocity between the origins of two frame connectors.

Always differentiates the relative position resolved in FrameA first, then
rotates the result into `resolve_in_frame` -- matching Modelica's
RelativeVelocity. Note this differs from `RelativeSensor`'s `v_rel` output,
which differentiates in whatever `resolve_in_frame` is set to.

This is a sensor: no forces or torques are exerted.
"""
component RelativeVelocity
  frame_a = Frame3D() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": -50, "y1": 450, "x2": 50, "y2": 550, "rot": 0}
      },
      "tags": []
    }
  }
  frame_b = Frame3D() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 950, "y1": 450, "x2": 1050, "y2": 550, "rot": 0}
      },
      "tags": []
    }
  }
  frame_resolve = Frame3D() if case(resolve_in_frame, ResolveInFrame.FrameResolve) {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 450, "y1": -50, "x2": 550, "y2": 50, "rot": 0}
      },
      "tags": []
    }
  }
  v_rel_x = RealOutput() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 130, "y1": 960, "x2": 230, "y2": 1060, "rot": 90}
      },
      "tags": []
    }
  }
  v_rel_y = RealOutput() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 450, "y1": 960, "x2": 550, "y2": 1060, "rot": 90}
      },
      "tags": []
    }
  }
  v_rel_z = RealOutput() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 770, "y1": 960, "x2": 870, "y2": 1060, "rot": 90}
      },
      "tags": []
    }
  }
  structural parameter resolve_in_frame::ResolveInFrame = ResolveInFrame.FrameA()
  "Relative position, resolved in frame_a"
  variable r_rel_a::Position[3]
  "Relative velocity, resolved in frame_a"
  variable v_rel_a::Velocity[3]
  variable v_rel::Velocity[3]
relations
  frame_a.f = [0, 0, 0]
  frame_a.tau = [0, 0, 0]
  frame_b.f = [0, 0, 0]
  frame_b.tau = [0, 0, 0]
  if case(resolve_in_frame, ResolveInFrame.FrameResolve)
    frame_resolve.f = [0, 0, 0]
    frame_resolve.tau = [0, 0, 0]
  end
  r_rel_a = resolve2(frame_a.R, frame_b.r_0 - frame_a.r_0)
  v_rel_a = der(r_rel_a)
  switch resolve_in_frame
    case FrameA
      v_rel = v_rel_a
    case World
      v_rel = resolve1(frame_a.R, v_rel_a)
    case FrameB
      v_rel = resolve_relative(v_rel_a, frame_a.R, frame_b.R)
    case FrameResolve
      v_rel = resolve_relative(v_rel_a, frame_a.R, frame_resolve.R)
  end
  [v_rel_x, v_rel_y, v_rel_z] = v_rel
metadata {
  "Dyad": {
    "icons": {"default": "dyad://MultibodyComponents/TwoFrameSensor.svg"},
    "labels": [
      {
        "label": "$(instance)",
        "x": 500,
        "y": 150,
        "rot": 0,
        "attrs": {"font-size": "140"}
      },
      {"label": "rel vel", "x": 500, "y": 680, "rot": 0}
    ]
  }
}
end

Flattened Source

"""
Measures the relative velocity between the origins of two frame connectors.

Always differentiates the relative position resolved in FrameA first, then
rotates the result into `resolve_in_frame` -- matching Modelica's
RelativeVelocity. Note this differs from `RelativeSensor`'s `v_rel` output,
which differentiates in whatever `resolve_in_frame` is set to.

This is a sensor: no forces or torques are exerted.
"""
component RelativeVelocity
  frame_a = Frame3D() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": -50, "y1": 450, "x2": 50, "y2": 550, "rot": 0}
      },
      "tags": []
    }
  }
  frame_b = Frame3D() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 950, "y1": 450, "x2": 1050, "y2": 550, "rot": 0}
      },
      "tags": []
    }
  }
  frame_resolve = Frame3D() if case(resolve_in_frame, ResolveInFrame.FrameResolve) {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 450, "y1": -50, "x2": 550, "y2": 50, "rot": 0}
      },
      "tags": []
    }
  }
  v_rel_x = RealOutput() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 130, "y1": 960, "x2": 230, "y2": 1060, "rot": 90}
      },
      "tags": []
    }
  }
  v_rel_y = RealOutput() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 450, "y1": 960, "x2": 550, "y2": 1060, "rot": 90}
      },
      "tags": []
    }
  }
  v_rel_z = RealOutput() {
    "Dyad": {
      "placement": {
        "diagram": {"iconName": "default", "x1": 770, "y1": 960, "x2": 870, "y2": 1060, "rot": 90}
      },
      "tags": []
    }
  }
  structural parameter resolve_in_frame::ResolveInFrame = ResolveInFrame.FrameA()
  "Relative position, resolved in frame_a"
  variable r_rel_a::Position[3]
  "Relative velocity, resolved in frame_a"
  variable v_rel_a::Velocity[3]
  variable v_rel::Velocity[3]
relations
  frame_a.f = [0, 0, 0]
  frame_a.tau = [0, 0, 0]
  frame_b.f = [0, 0, 0]
  frame_b.tau = [0, 0, 0]
  if case(resolve_in_frame, ResolveInFrame.FrameResolve)
    frame_resolve.f = [0, 0, 0]
    frame_resolve.tau = [0, 0, 0]
  end
  r_rel_a = resolve2(frame_a.R, frame_b.r_0 - frame_a.r_0)
  v_rel_a = der(r_rel_a)
  switch resolve_in_frame
    case FrameA
      v_rel = v_rel_a
    case World
      v_rel = resolve1(frame_a.R, v_rel_a)
    case FrameB
      v_rel = resolve_relative(v_rel_a, frame_a.R, frame_b.R)
    case FrameResolve
      v_rel = resolve_relative(v_rel_a, frame_a.R, frame_resolve.R)
  end
  [v_rel_x, v_rel_y, v_rel_z] = v_rel
metadata {
  "Dyad": {
    "icons": {"default": "dyad://MultibodyComponents/TwoFrameSensor.svg"},
    "labels": [
      {
        "label": "$(instance)",
        "x": 500,
        "y": 150,
        "rot": 0,
        "attrs": {"font-size": "140"}
      },
      {"label": "rel vel", "x": 500, "y": 680, "rot": 0}
    ]
  }
}
end

Test Cases

No test cases defined.

Related

• Examples

• Experiments

• Analyses

• Tests

  • SensorsTest