Estimating tissue stiffness from ringing

A surgical system, comprising:

• a surgical instrument comprising an end effector that includes a first clamp arm and a second clamp arm movable relative to the first clamp arm between an open configuration and a closed configuration to capture tissue therebetween;
• a first sensor to sense the end effector contacting tissue;
• a second sensor to sense a gap between the first and second clamp arms;
• and
• a controller in operable communication with the surgical instrument and the first and second sensors, wherein the controller is operable to:
• detect, with the first sensor, the end effector contacting tissue as the second clamp arm is transitioning toward the closed configuration;
• sense, for an amount of time with the second sensor, the gap between the first and second clamp arms based on the detection, thereby obtaining sensed gap data;
• generate a regression fit according to the sensed gap data;
• and
• determine a number of times that the sensed gap data crosses the regression fit, the number of times being indicative of the stiffness of the tissue.

A surgical system, comprising:

• a surgical instrument comprising an end effector that includes a first clamp arm and a second clamp arm movable relative to the first clamp arm between an open configuration and a closed configuration to capture tissue therebetween;
• a sensor;
• a controller in operable communication with the surgical instrument and the sensor, wherein the controller is operable to:
• detect, with the sensor, the end effector contacting tissue as the end effector is transitioning toward the closed configuration;
• sense, for an amount of time with the sensor, the gap between the first and second clamp arms based on the detection, thereby obtaining sensed gap data;
• observe an oscillation in the sensed gap data;
• and
• determine a stiffness of the tissue based on the oscillation.