<< Click to Display Table of Contents >> Navigation: Getting Started Tutorials - MechDesigner > Tutorial 5: Kinematic Function Blocks for Motion > Step 5.3: The Motion-Dimension FB |
A)A Motion-Dimension FB identifies a Part, called a Motion-Part, that we want to move with a motion.
B)A Motion-Dimension, and the Motion-Dimension FB, define the position of the Motion-Part
C)We specify the value of the Motion-Dimension with two parameters:
•Base-Value : edit in the Motion-Dimension dialog-box - it is the position of the Motion-Part when a wire is not at the input-connector.
•Motion-values : the position (and velocity and acceleration) values, which a wire provides at its input-connector.
Motion-Dimension = Base-Value + Motion-Values
D)There are two types of Motion-Parts:
•Rocker = Part + Pin-Joint + Motion-Dimension FB
•Slider = Part + Slide- Joint + Motion-Dimension FB
Kinematics-FB toolbar > Add Motion-Dimension FB |
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The Command-Manager has three selection-boxes.
Notes:
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The icon of the FB in the graphic-area is different to the icon in the Kinematic-FB toolbar. |
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The Motion-Dimension FB in the graphic-area that identifies a Rocker |
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The Motion-Dimension FB in the graphic-area that identifies a Slider |
Prepare the model so that these elements have these properties.
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![]() Rotating Free-Part |
Preparation example: •Pin-Joint •The Points at Pin-Joint •Lines •Part •Part |
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Kinematic FB toolbar > Motion-Dimension FB (right of Graphic-Area >>) |
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Element #1: PIN-JOINT The Pin-Joint is a joint between two Parts, and: •One Part is a kinematically-defined Part •One Part is a free Part |
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Elements #2 and #3: LINES Each Line must be a child to a Point that is also a child to the Pin-Joint (Element #1) •Element #2: a Line in the kinematically-defined Part •Element #3: a Line in the free Part Click |
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![]() Rocker: kinematically-defined Part |
Result: a Rocker A Motion-Dimension FB to specify the angle between Lines, Elements #2 and #3 The dimension
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Kinematics-Tree for a Rocker When we add a Motion-Dimension FB to a Pin-Joint, we identify it as a Rocker in the Kinematics-Tree. The kinematic elements are: •'Part' + 'Pin-Joint' + 'Motion-Dimension' = 'Rocker' |
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Note: There are two different mouse-actions: To move the
To move the
Hover(FB)= move your mouse above the FB icon. DRAG = Mouse-Button-Down, and move your mouse-pointer, Mouse-Button-Up
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Prepare the model so that these elements have these properties.
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![]() A Sliding-Part |
Preparation example: 1.Two Parts One is a kinematically-defined Part (Green Part-Outline)...the Base-Part The other is a free Part (Blue Part-Outline) 2.The two Parts are joined... with a Slide-Joint Note : the Points |
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Kinematic FB toolbar > Motion-Dimension FB (right of Graphic-Area >>) |
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Element #1: SLIDE-JOINT The Slide-Joint is a joint between two Parts •One Part is a kinematically-defined Part •One Part is a free Part |
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Elements #2 and #3: POINTS Each Point must be a child to a Line that is also a child to the Slide-Joint. (Element #1) •Element #2: a Point that is a start-Point or end-Point of a Line in the kinematically-defined Part •Element #3: a Point that is a start-Point or end-Point of a Line in the free Part
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![]() A Slider |
Click Result: a Slider The Motion-Dimension FB to specify the linear distance between Points, Elements #2 and #3 All Parts are now kinematically-defined Parts The dimension
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Kinematics-Tree When we add a Motion-Dimension FB to a Slide-Joint, we identify it as a Slider in the Kinematics-Tree. The kinematic elements are: •'Part' + 'Slide-Joint' + 'Motion-Dimension' = 'Slider' |
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Note: Two(2) different mouse-actions in the graphic-area To MOVE the
To MOVE the
Hover(FB)= move your mouse above the FB icon. DRAG = Mouse-Button-Down, and move your mouse-pointer, Mouse-Button-Up
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After you add the Motion-Dimension FB, you can edit it to specify the starting-Position of the Motion-Part. To edit the Motion-Dimension FB: 1.Double-click the Motion-Dimension FB in the graphic-area The Motion-Dimension FB dialog-box opens. 2.Edit the: - or - o( Base-Value + Motion Value ) It is best to think of the: •Base-Value as the position of the Motion-Part when a wire is not connected to the input-connector. •Base-Value + Motion-Value as the position of the Motion-Part when a wire is connected to the input-connector. Directions separator: •Edit the positive/negative directions of the Base-Value •Edit the positive/negative directions of the Motion-Values. |
STEP 1: Add two Linear-Motion FBs to the graphic-area. STEP 2: Add a Graph FB to the graphic-area STEP 3: Connect a wire from the Linear-Motion FB(1) to the Graph FB X-axis (the bottom connector). STEP 4: Edit the Base-Part and add a Line STEP 5: Add a Part and a Pin-Joint to join one end of the Part to the end of a Line in the Base-Part. STEP 6: Add a Motion-Dimension FB to identify the Part as a Rocker. STEP 7: Connect the other Linear-Motion FB(2) to the Motion-Dimension FB, and from the Motion-Dimension FB to the Graph Y-axis STEP 8: Double-click Linear-Motion FB(2) ; edit the Phase Offset to 30 STEP 9: Double-click Motion-Dimension FB ; edit the Base-Value to 110 STEP 10: Double-click Graph FB to show the plot of the variables. |
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The image shows the elements in the graphic-area after Steps 1-10 - I have arrange the image to help
The Linear-Motion FB(1) We have connected a wire from the Linear-Motion FB(1) directly to Motion-Dimension FB We have connected a wire from the Motion-Dimension FB directly to the Y1 input of the Graph FB The Motion-Dimension dialog-box |
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The Base-Value of the Motion-Dimension is 110º
The Master-Machine-Angle (MMA) is 120º Thus, the output from the Linear-Motion FB is 120º + 30º = 150º.
Thus, the input to the Motion-Dimension FB = 150º.
The Base-Value Thus, the Rocker angle is at 110º + 150º = 260º.
The output from the Motion-Dimension FB is also the input to the Graph FB.
When you open the Graph FB, the vertical cursor If you set the cursor to 120º, the Y-axis value is 260º. |
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The Graph shows a plot of the output of the Motion-Dimension FB(y-axis) against the Linear-Motion FB(X-axis) The DRO |