Step 5.4: MMA, Kinematic Function-Blocks, Graph FB
Contents
Basic Function-Blocks
In this Step, we review the:
| • | The Master-Machine-Angle |
| • | Three of the basic Kinematic FBs that we use frequently |
| • | Make a plot of motion-values with a Graph FB |
The Master Machine Angle (MMA) 'Function-Block'
The Master-Machine-Angle is at the bottom and right of the application.
When the Master Machine Angle changes its angle, all kinematic-chains move to a new position that is determined by the new value of the Master-Machine-Angle. When you use Cycle ['C' key on your keyboard], Zero(0) of the MMA is the machine 'home' position. You can change the value of the Master Machine Angle in three ways
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Basic Kinematic Function-Blocks
To add these Function-Blocks [FBs] to the graphic-area:
| 1. | Click the FB in the Add menu or Kinematic-FB toolbar |
| 2. | Click again in the graphic-area. |
The FB then shows in the graphic-area.
You connect FBs with wires. You must edit each FB of course.
The Linear Motion FB
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The motion-values at the output-connector of the Linear-Motion FB increase linearly at the same rate as the MMA. Linear-Motion FB Output Angle ψ[º] = Master-Machine-Angle[º] + θ[º] Use a Linear-Motion FB to synchronize each kinematic-chain with the Master-Machine Angle.
The 'virtual' input to the Linear-Motion FB is the Master-Machine-Angle. |
The Gearing FB
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The 'Gearing Function-Block' has three parameters:
The Mathematical Equation for the Gearing FB is: Output [δ] = N(Input + α) + β Notes: N this is a 'gearing' ratio. When N > 1, the output motion > input motion (opposite to normal a gear-box where a gear ratio of N > 1 reduces the output speed. If N > 0 then the output δ > 0 has the same sign (assuming α and β are zero). The output is not negative. |
The Motion FB
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We use a Motion Function-Block to link a motion in a Motion name-tab to a Motion-Part To link the Motion FB to a Motion name
The list is a complete list of motion name that are in MotionDesigner Motion name-tabs We design the motions in MotionDesigner, of course. You can design simple or complex motions in MotionDesigner. |
Make a plot of motion-values of FBs with a Graph FB
To find the motion-values at the output-connectors of a FB, simply connect a wire from its output-connector to the input-connector of a Graph FB. Remember, when you connect two FBs with a wire, the motion-values at the output-connector of one FB is the same as the motion-value at the input-connector of the FB with which you connect the wire.
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Below: a screen capture of the various elements, cleverly positioned, after Steps 1–7. There are two Linear-Motion Function-Blocks connected to a Graph FB. |
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Note: the Linear-Motion FB in this image is old. However, the main parameter has not changed. In the image to the left, the 'top' Linear-Motion FB is red. It is connected it to the top (Y1) input of the Graph FB SETTINGS The dialog for the 'top' Linear-Motion FB is open Master-Machine-Angle = 120
GRAPH CONNECTIONS: X-AXIS -'bottom' Graph connection The 'bottom' Linear-Motion FB is connected to the X-axis of the Graph FB. The phase of the 'bottom' Linear-Motion FB is '0'. Therefore, the motion value at the output-connector of the 'bottom' Linear-Motion FB, and the input to the X-axis of the Graph FB is: = MMA = 120 Y-AXIS – 'top' Graph connection The 'top' Linear-Motion FB is connected to the Y1-Axis of the Graph FB. The phase of the 'top' Linear-Motion FB is +30 Therefore, the motion value at the output-connector of the 'top' Linear-Motion FB, and the input to the Y1-Axis of the Graph FB is: = MMA + Phase = 120 + 30 = 150 |
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Digital Readouts (DROs) The DROs below the graphs indicate the values at the position of the vertical red cursor |
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Gearing FB
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We have cleverly positioned the elements after we have followed the steps above. |
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 Master Machine Angle (MMA) Slider @ is at 120º, corresponding to the graph cursor position. |
Note: Gearing FB in this image is old. However, the parameters have not changed. The Gearing FB dialog box is open We have selected the 'Use Ratio of Pulley Teeth?' option We have entered:
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X-AXIS: 'Bottom' Graph Connection The 'bottom' Linear-Motion FB is connected to the X-axis of the Graph FB We have not edited the phase of the 'bottom' Linear-Motion FB. Therefore, it equals the MMA = MMA = 120 Y-AXIS: 'top' Graph connection The 'top' Linear-Motion FB is connected to the Gearing FB, which is connected to the Graph FB The output of the Linear-Motion FB is +30 The input to the Gearing FB = 120 + 30 = 150 The output from the Gearing FB and input to the Graph FB is: = (20/10)*(120+30)+20)+10 = 350 The Digital Readout [DRO] lists the values of the variables connected to the Graph FB. X-axis = 120 |
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For Information: Gearing FB Output [when MMA 0] = 2 * ((0+30) + 20) + 10 = 110 Gearing FB Output [when MMA 360] = 2 * ((360+30) + 20) + 10 = 830 |
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; Y1-Axis = 350
Motion FB
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We have cleverly positioned the elements after we have followed the steps above. |
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Top Linear-Motion FB >> Motion FB >> Y1 Graph FB Connect
MotionDesigner is open MotionDesigner shows the Motion that is linked to the Motion FB |
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The Motion 'Function' in MotionDesigner is the default motion – a Rise-Dwell-Return-Dwell. |
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Bottom Linear-Motion FB >> Graph FB The output of the Linear-Motion FB is equal to the Master-Machine-Angle [MMA]. The MMA is 120 The DRO for the X-axis 120
The Graph
The motion graph shows that the Y-axis is still 100mm when the X-axis is 150. |
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Master-Machine-Angle (MMA) Slider @ is at 120.