Prototyping Your Door-Knob Hole Cutting Machine using NI Motion Assistant

Overview

This application cuts circular holes in wooden doors to place door knobs. The doors with slits made in them are placed under the saw. The saw is lowered into the slit and then moved in a circular pattern to ensure that a perfectly round hole is cut. The saw is made to move in two circles to make sure that the cut is clean, as shown in the figure.

 

The system is comprised of the following:

· A saw mounted on an XY stage
· A vertical axis that moves the saw assembly up or down to insert the saw into the pre-made slit in the door

You can prototype the motion part of this application by creating a script in NI Motion Assistant using the following steps:

Step 1. Reference Move—Moves the XY stage into its starting position using the find home move type.

Insert a Reference Move step.

1. Click the Add Step button on the far left side of the application window.
2. Click the Reference Move button.
3. Click the Configure tab on the dialog box at the bottom of the new screen.

4. Click the Move Constraints tab on the dialog box. Enter the following parameters: 5. Click the Reference Parameters tab on the dialog box, and enter the following information: 6. Check the box next to the Reset Position Counters button to reset the position of the move to zero after the reference move.

Step 2. Reference Move—Moves the vertical axis into its initial position.

Insert a Reference Move step.

1. Click the Add Step button on the far left side of the application window.
2. Click the Reference Move button.
3. Click the Configure tab on the dialog box at the bottom of the new screen.

o Because this move operates the two axes of the XY stage, click the 1D button.
o Device: Choose the motion controller.
o Units: Select counts (steps).
o Axis: Choose Axis 3 because it is the vertical axis.

4. Click the Move Constraints tab on the dialog box. Enter the following parameters:

5. Click the Reference Parameters tab on the dialog box, and enter the following information: 6. Check the box next to the Reset Position Counters button to reset the position of the move to zero after the reference move.

Step 3. Straight Line Move—Moves the vertical axis down so that the saw is inserted into the pre-made slit in the door.

Insert a Straight-Line Move step.  This step prototypes moving the vertical axis down so that the saw is inserted into the pre-made slit in the door.

1. Click the Add Step button on the far left side of the application window.
2. Click the Straight-Line Move button.  NI Motion Assistant remembers the Configure and Move Constraints tab settings of the previous step, so it is necessary to cahnge the settings only ion the Position tab.
3. Click the Position tab, and set the following parameters:

These parameters move the vertical axis downward by 10,000 counts to an absolute position of -10,000. 

Step 4. Arc Move—Moves the XY stage in a circle. This arc is configured for blending.

Insert an Arc Move step.  This step prototypes the first circle.

1. Click the Add Step button on the far left side of the application window.
2. Click the  Arc Move step on the far left side of the window.
3. Click the Configure tab and set X Axis to Axis 1 and Y Axis to Axis 2.
4. Click the Move Constraints tab, and set the Velocity parameter to 20000.
5. Click the Arc Parameters tab, and set the following parameters:

6. To blend the move, right-click the Arc Move step in the list of steps you have added to the script and select Blend this Step.

Step 5. Arc Move—Moves the XY stage in another circle of half the radius of the previous arc.

Insert an Arc Move step.  This step prototypes the second circle, which is one-half the size of the first.

1. Click the Add Step button on the far left side of the application window.
2. Click the Arc Move step on the far left side of the window.
3. Click the Move Constraints tab, and set the Velocity parameter to 10000. This change is made because the second arc will have to travel at half the speed of the first arc to maintain the correct angular velocity.
4. Click the Arc Parameters tab, and set the following parameters:

4. To blend the move, right-click the Arc Move step in the list of steps you have added to the script and select Blend this Step.

Because blending runs the end of the first move along with the beginning of the second move, it is possible that the effect on the move's trajectory may be unacceptable for the tolerances of the application.  You can see the effect of blending by using the zoom feature of the 2D position view to look closely at the exchange between the first arc and the second.

Step 6. Convert to LabVIEW or C code.

You have finished creating the prototype motion script. To test the script, complete the following steps:

1. Initialize the motion controller in MAX.
2. Click the Run button at the top of the Motion Assistant screen to run the motion script.

Note To run this motion script as written, you must have a complete motion system connected to motors. If you are prototyping a motion script with only a motion controller and no external motion hardware, delete the Reference Move step, configure the motion controller for open-loop steppers, and then run the script.

To save the motion script, select File»Save, or press <Ctrl-S>. You can now convert your project to LabVIEW or C code by clicking on Tools»Generate Code.

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