Modular battery powered handheld surgical instrument and methods therefor

A method of controlling a modular battery powered handheld surgical instrument, the surgical instrument comprising a battery, a user input sensor, a controller, a radio frequency (RF) drive circuit, an ultrasonic transducer, an ultrasonic transducer drive circuit, and an end effector, the end effector comprising an electrode electrically coupled to RF drive circuit, an ultrasonic blade acoustically coupled to the ultrasonic transducer, and a sensor to measure tissue parameters, the method comprising:

• applying, by the RF drive circuit, an RF current drive signal to the electrode;
• applying and maintaining, by the ultrasonic transducer drive circuit, an ultrasonic drive signal to the ultrasonic transducer to acoustically excite the ultrasonic blade at a resonant frequency;
• and
• simultaneous to maintaining the ultrasonic drive signal at the resonant frequency, controlling, by the controller, a wave shape of the RF current drive signal that is stored in a look up table based on one or more of a measurement of a tissue physical characteristic, a measurement of a tissue electrical characteristic, and data received from one or more user control component sensors, such that power is maximized when combined with the ultrasonic drive signal.