DETECTION SYSTEM FOR POWER TOOL

摘要

Power tool includes a movable blade and a detection system for detecting contact between the blade and an object. Detection system includes an excitation plate capacitively coupling the drive signal to the movable blade. A circuit generates 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 calculates an energy of the blade current signal considering the in-phase and the quadrature components. The circuit compares 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.