Logger Pro offers an automatic graph match generation feature. Graph matching is an exercise useful in teaching students how to interpret graphs. Usually graph matching is done with a Motion Detector, but other sensors can be used for this purpose. Examples here will use the Motion Detector.
In graph matching, a target graph is drawn and then data collection is started. The student walks or moves in front of the Motion Detector so as to generate a graph that comes as close as possible to the target graph. Performing a good match requires understanding the concepts of intercept and slope, as well as the measurement being graphed. Matching a velocity graph is much harder than matching a position graph.
When a Motion Detector or a Go!Motion is active, Logger Pro places a button on the toolbar to generate a target graph.
Click the toolbar button, or choose Graph Match from the Analyze menu, to insert a target graph. Repeat to get a different target graph. Click Collect to take data, moving so as to match the target graph as closely as possible.
The range of the target graph is determined by the vertical extent of the graph. For example, if the vertical axis runs from 0 to 3 meters, the target graph will be within that range. If you want to limit the target graph to distances within 2 meter, just rescale the graph so that the upper limit is 2 meters, and request a new target graph.
If a sensor has related graphs, then the target graph is correctly drawn on all graphs. For example, if both a Position and Velocity graph as present, the Velocity target graph will be the derivative of the Position graph.
If you add a legend to the graph, Logger Pro will display the Root-Mean-Square-Error (RMSE) between the target graph and the collected data. This value is a measure of how close the two graphs are to one another. Smaller is better. The RMSE has the same units as the vertical axis of the graph. To add a legend, select the graph and choose Graph Options from the Options menu. Check the Legend option, and click OK.
The complexity of the target graph can be set on a per-file basis by choosing Settings for (filename) from the File menu. You can choose what kinds of graph segments are used (constant, linear, or quadratic) and how many of these segments are used in the target graph.
Graph matching can also be done with the Draw Prediction feature of Logger Pro. Rather than using the automatically generated target graph, draw a target graph using the mouse.