Methods, systems, and devices for controlling electrosurgical tools

1. A surgical system, comprising:

a surgical tool including an elongate shaft, an end effector at a distal end of the elongate shaft, and a housing at a proximal end of the elongate shaft, the end effector being configured to selectively deliver radiofrequency energy and ultrasound energy to tissue engaged by the end effector; and

a control system configured to:

cause the end effector to selectively deliver the radiofrequency energy and the ultrasound energy to the tissue, and

vary a force applied by the end effector to the tissue engaged by the end effector based on whether the surgical tool is operating in a first mode in which radiofrequency energy but not ultrasound energy is being delivered to the tissue, is operating in a second mode in which both radiofrequency energy and ultrasound energy are being applied to the tissue, and is operating in a third mode in which ultrasound energy but not radiofrequency energy is being applied to the tissue;

wherein the force applied by the end effector to the tissue is greater in the first and third modes than in the second mode.

2. The surgical system of claim 1 , further comprising a sensor configured to sense impedance of the tissue engaged by the end effector;

wherein the control system is configured to vary the force also based on the sensed impedance.

3. The surgical system of claim 2 , wherein, when the surgical tool is operating in the first mode, the control system is configured to reduce the force in response to the sensed impedance decreasing and to increase the force in response to the sensed impedance increasing.

4. The surgical system of claim 1 , wherein the end effector is configured to clamp tissue, and the force is a compressive force on the clamped tissue.

5. The surgical system of claim 4 , wherein the surgical tool includes a closure assembly disposed at least partially in the housing and configured to be actuated to move the end effector between an open position and a closed position; and

the control system is configured to vary the force by opening or closing the end effector.

6. The surgical system of claim 1 , wherein the surgical tool operating in the first mode causes coagulation of the tissue engaged by the end effector, the surgical tool operating in the second mode enhances the coagulation, and the surgical tool operating in the third mode causes cutting of the tissue engaged by the end effector.

7. The surgical system of claim 1 , further comprising a tool driver of a robotic surgical system configured to operatively connect to the housing, the control system being a component of the robotic surgical system.

8. The surgical system of claim 7 , wherein the tool driver includes at least one motor configured to drive the delivery of the radiofrequency energy, configured to drive the delivery of the ultrasound energy, and configured to vary the force applied by the end effector.

9. A surgical system, comprising:

a surgical tool including an elongate shaft, an end effector at a distal end of the elongate shaft, and a housing at a proximal end of the elongate shaft, the end effector being configured to selectively deliver radiofrequency energy and ultrasound energy to tissue engaged by the end effector; and

a control system configured to:

cause the end effector to selectively deliver the radiofrequency energy and the ultrasound energy to the tissue, and

vary a force applied by the end effector to the tissue engaged by the end effector based on whether the surgical tool is operating in a first mode in which radiofrequency energy but not ultrasound energy is being delivered to the tissue, is operating in a second mode in which both radiofrequency energy and ultrasound energy are being applied to the tissue, and is operating in a third mode in which ultrasound energy but not radiofrequency energy is being applied to the tissue;

wherein in the second mode more ultrasound energy than radiofrequency energy is being applied to the tissue, the surgical tool is configured to operate in a fourth mode in which both radiofrequency energy and ultrasound energy are being applied to the tissue and more radiofrequency energy than ultrasound energy is being applied to the tissue, and the control system is configured to vary the force also based on whether the surgical tool is operating in the fourth mode.

10. The surgical system of claim 9 ,

wherein the force applied by the end effector to the tissue is greater in the first and third modes than in the second mode.

11. The surgical system of claim 9 , further comprising a sensor configured to sense impedance of the tissue engaged by the end effector;

wherein the control system is configured to vary the force also based on the sensed impedance; and

wherein, when the surgical tool is operating in the first mode, the control system is configured to reduce the force in response to the sensed impedance decreasing and to increase the force in response to the sensed impedance increasing.

12. A surgical system, comprising:

a surgical tool including an elongate shaft, an end effector at a distal end of the elongate shaft, a housing at a proximal end of the elongate shaft, and a closure assembly disposed at least partially in the housing and configured to be actuated to move the end effector between an open position and a closed position, the end effector being configured to selectively deliver radiofrequency energy and ultrasound energy to tissue clamped by the end effector;

a sensor configured to sense impedance of the tissue engaged by the end effector;

a motor configured to drive the closure assembly; and

a control system configured to control the motor to drive the actuation of the closure assembly such that the end effector applies a variable compressive force to the tissue clamped thereby based on the sensed impedance and based on whether both radiofrequency energy and ultrasound energy are currently being applied to the tissue clamped by the end effector or only one of radiofrequency energy and ultrasound energy is currently being applied to the tissue clamped by the end effector;

wherein, when only one of radiofrequency energy and ultrasound energy is currently being applied, the control system is configured to reduce the compressive force in response to the sensed impedance decreasing and is configured to increase the compressive force in response to the sensed impedance increasing.

13. The surgical system of claim 12 , wherein the compressive force is less when both radiofrequency energy and ultrasound energy are currently being applied than when only one of radiofrequency energy and ultrasound energy is currently being applied.

14. The surgical system of claim 13 , wherein, when both radiofrequency energy and ultrasound energy are currently being applied, the compressive force is less when more ultrasound energy than radiofrequency energy is currently being applied than when more radiofrequency energy than ultrasound energy is currently being applied.

15. The surgical system of claim 12 , wherein the sensed impedance is indicative of whether both radiofrequency energy and ultrasound energy are currently being applied or only one of radiofrequency energy and ultrasound energy is currently being applied.

16. The surgical system of claim 12 , further comprising a tool driver assembly configured to be operatively connected to the housing, the tool driver assembly including the motor, and the tool driver assembly and the control system being components of a robotic surgical system.

17. The surgical system of claim 12 , wherein the surgical tool includes at least two electrodes configured to apply the radiofrequency energy to the tissue.

18. A surgical system, comprising:

a surgical tool including an elongate shaft, an end effector at a distal end of the elongate shaft, a housing at a proximal end of the elongate shaft, and a closure assembly disposed at least partially in the housing and configured to be actuated to move the end effector between an open position and a closed position, the end effector being configured to selectively deliver radiofrequency energy and ultrasound energy to tissue clamped by the end effector;

a sensor configured to sense impedance of the tissue engaged by the end effector;

a motor configured to drive the closure assembly; and

a control system configured to control the motor to drive the actuation of the closure assembly such that the end effector applies a variable compressive force to the tissue clamped thereby based on the sensed impedance and based on whether both radiofrequency energy and ultrasound energy are currently being applied to the tissue clamped by the end effector or only one of radiofrequency energy and ultrasound energy is currently being applied to the tissue clamped by the end effector;

wherein the compressive force is less when both radiofrequency energy and ultrasound energy are currently being applied than when only one of radiofrequency energy and ultrasound energy is currently being applied.

19. The surgical system of claim 18 , wherein, when only one of radiofrequency energy and ultrasound energy is currently being applied, the control system is configured to reduce the compressive force in response to the sensed impedance decreasing and is configured to increase the compressive force in response to the sensed impedance increasing.

20. The surgical system of claim 18 , wherein, when both radiofrequency energy and ultrasound energy are currently being applied, the compressive force is less when more ultrasound energy than radiofrequency energy is currently being applied than when more radiofrequency energy than ultrasound energy is currently being applied.