A robotic surgical system is provided that includes an electromechanical tool coupled to a surgical instrument such as an end effector adapted to apply ultrasound energy to tissue when the end effector holds the tissue. The electromechanical tool is mounted on an electromechanical arm and configured to move relative to the arm. A controller operatively coupled to the tool and the arm measures electrical impedance of tissue as ultrasound energy is applied to the tissue by the end effector. The controller determines, based on the tissue impedance measurements, that the tissue is fully cauterized. In response to the detection, the surgical system automatically lifts the end effector, either by lifting the arm to which it is coupled or independently from that arm, thereby the end effector cuts the cauterized tissue to complete the tissue cauterization/cutting. The controller also determines and controls a velocity with which the end effector is lifted.