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umar khan

How is the force due to Z piezo motion determined?

Hello, Can you please tell me how the force due the Z piezo motion can be found when the Z piezo motion is arbitrary. In the VEDA manual (http://nanohub.org/resources/15166/download/VEDA_Manual.pdf), this force (referred to as F_i^Z) is determined for the special case when the Z piezo is moving with constant velocity (Eq. 109-110).

This question arises for the case when the Z piezo movement is generated by a PI controller in a feedback loop, as illustrated in Fig. 88 of the same manual.

Thank you.

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    Daniel Kiracofe

    See the text immediately below equation 74. Basically, F_iz is neglecting in all of the scanning tools (i.e. whenever there is a PI controller). The reasoning is that Z velocity is typically very slow in those cases, especially when compared to the other movements of the cantilever. It is only on the approach curves tools (FZ curves, dynamic approach curves) that we include F_iz. Does that answer the question?

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      umar khan

      I understand that the F_i^Z force is neglected. However then how is the effett of the “Z” signal generated by the PI controller in Figure 88 simulated. Is the value of “Z” used to determine “\bar” in Eq. 97? ( where “\bar” is used to determine the normalized tip sample interaction force \bar} )

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        umar khan

        correction: please read “bar” as “d bar”, i.e the normalized tip sample separation.

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