| 摘要 |
A power tool is disclosed. The power tool may comprise a movable blade and a detection system for detecting contact between the blade and an object. The detection system may comprise an excitation plate capacitively coupling the drive signal to the movable blade and a circuit in communication with the excitation plate. The circuit may be configured to generate an in-phase component signal and a quadrature component signal from a blade current signal indicative of the instantaneous current drawn by the movable blade and calculate an energy of the blade current signal considering the in-phase component and the quadrature component. The circuit may be further programmed to compare the energy of the blade current signal to an adaptive trigger threshold to detect contact between the blade and the object based on whether the energy of the blade current signal is greater than the adaptive trigger threshold. The adaptive trigger threshold may be based on a sum of a first plurality of values comprising a fixed direct current (DC) offset, and a mean of the energy of the blade current signal.
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