Pressure control in ultrasonic surgical instruments

A surgical system, comprising:

• a surgical instrument, comprising:
• an ultrasonic blade;
• a clamp arm movable relative to the ultrasonic blade;
• an ultrasonic transducer energizable to drive the ultrasonic blade;
• and
• a motor energizable to move the clamp arm relative to the ultrasonic blade;
• a sensor to sense a gap between the ultrasonic blade and the clamp arm;
• and
• a controller in operable communication with the ultrasonic transducer, the motor, and the sensor, wherein the controller is operable to operate the surgical instrument in:
• a first mode in which the controller is operable to maintain, with the motor, a magnitude of the gap between the ultrasonic blade and the clamp arm while driving the ultrasonic blade with the ultrasonic transducer;
• and
• a second mode in which the controller is operable to change, with the motor, the magnitude of the gap between the ultrasonic blade and the clamp arm while driving the ultrasonic blade with the ultrasonic transducer.

A non-transitory computer readable medium storing instructions that, when executed by a processor, causes the processor to:

• sense a gap between a clamp arm of a surgical instrument and an ultrasonic blade of a surgical instrument;
• drive, with an ultrasonic transducer, the ultrasonic blade;
• and
• operate the surgical instrument in:
• a first mode in which the processor is operable to drive, with a motor, the clamp arm to maintain a magnitude of the gap between the ultrasonic blade and the clamp arm while driving the ultrasonic blade;
• and
• a second mode in which the processor is operable to drive, with the motor, the clamp arm to change the magnitude of the gap between the ultrasonic blade and the clamp arm while driving the ultrasonic blade.