请教怎样理解力曲线参数设置面板上的Z scan start，及手动tune中一些问题

Z scan start— Sets the maximum voltage applied to the Z electrodes of the piezo during the force plot operation. The triangular waveform is offset up and down in relation to the value of this parameter. Increasing the value of the Z scan start parameter moves the sample closer to the tip by extending the piezo tube. The units of this item are volts or nanometers, depending on the setting of the Units parameter. The initial value of Z scan start is equal to
the average Z-center voltage defined by the feedback just prior to entering Force Plot mode. Decreasing the value of this parameter shifts the force curve on the display to the left, while increasing the parameter shifts the curve to the right。

做力曲线时，我觉得只要每一步都应该严格按照操作手册就没有问题。