Watch Three Point Frame

Watching a three point frame is a fairly unique operation. It involves watching three 3-DOF devices simultaneously, wherein the device’s points define a frame’s origin, X axis, and XY plane. The watch window then shows the transform of this frame in the working frame.

For this command to be useful, the three instruments must be aligned to the same coordinate system—that is, they must be located to each other. Otherwise, the spatial positioning of the three points won’t make sense.

If you have an object in which three points define a repeatable frame, you can use this command to easily determine the position and orientation of the object. If you then create and activate a corresponding coordinate frame representing a desired end state, this watch window represents the deviation needed to get to the active frame.

To Watch a Three Point Frame:

1. Ensure that the interfaces for three separate 3-DOF devices are running.

2. From the menu, select Watch Window>Add Three Point Frame.

3. Select the instrument whose point will define the origin of the frame.

4. Select the instrument whose point defines the X axis of the frame.

5. Select the instrument whose point lies in the XY plane.

 

Watch Two Point Axis Alignment

Often, two points defining the axis of an object must be measured and adjusted to either match a nominal orientation, or to match a prescribed pitch and yaw.

This watch window allows you to measure two discrete points with a single instrument. The watch window then indicates the pitch (elevation) and yaw (azimuth) of the measured axis relative to the prescribed axis.

The working coordinate frame defines the vertical direction—there- fore its Z axis is used in the calculations.

To Watch an Axis Using Two Point Axis Alignment:

1. Measure or construct two points along the axis that serve as the nominal or “goal” points.

2. From the menu, select Watch Window>Watch Two Point Axis Alignment.

3. Select the instrument to use for measurements.

4. Select the first and second points, defining the X axis (from the first to the second). The measured X axis is along the direction from the first to the second points. The Z axis is clocked along the working Z axis, therefore if pitch to gravity is desired, this axis should be along gravity.

5. The Monitor Axis dialog appears.

6. Specify the group name in the text field, if desired.

7. Click Target 1 and Target 2 to measure the points and associate them with the ends of the axis. The pitch and yaw values will update.

8. To automatically measure both targets (assuming you have at least two targets installed and a steerable instrument), click the Cycle Targets button. The instrument will point, search for, lock on, and measure each target.

9. As repeated measurements come in, SA will automatically increment the group name and put each repeated measurement in a separate group.