System and Method for Modulating Tissue Retraction Force in a Surgical Robotic System

1 . A medical robotic system comprising:

at least a first robotic arm configured to support a surgical instrument having an end effector,

a sensor positioned to determine a magnitude of force or torque applied to tissue of a patient using the instrument;

wherein the robotic system includes a mode of operation operable to dynamically adjust the end effector position within the patient using the first robotic arm to substantially maintain a target direction and magnitude of forces or torques applied by the end effector.

2 . The system of claim 1 , further including at least one input device operable to set the target direction and magnitude.

3 . The system of claim 2 , wherein the input device includes a user control input operable to command robotic motion of the robotic arm to position the end effector in contact with tissue and to apply a force or torque to the tissue at a first magnitude and in a first direction, and to instruct the system to set the target direction and target magnitude at the actual magnitude and actual direction.

4 . The system of claim 2 , wherein the first robotic arm includes a manual mode in which the end effector is manually movable by the hand of a user to position the end effector in contact with tissue and to apply an actual force or torque to the tissue at an actual magnitude, and wherein the system includes a surgeon input operable to instruct the system to set the target magnitude at the actual magnitude.

5 . The system of claim 1 , where the system includes:

a second robotic arm supporting a second instrument having a second end effector,

a user input operable to command robotic motion of the second robotic arm to position the second end effector in contact with tissue and to apply a force or torque to the tissue at a second magnitude and in a second direction

wherein the second robotic arm includes a mode of operation in which the second arm is controlled by a user using user input and the first arm is autonomously controlled to cause the second effector to apply force or torque to tissue using force or torque having a first direction and a first magnitude, the first direction and first magnitude determined by the system using the second direction and second magnitude.

6 . The system of claim 5 , wherein the in the mode of operation movement of the second effector mirrors movement of the first end effector relative to a defined plane.

7 . The system of claim 1 , where the system includes a plurality of arms, wherein at least two or more arms are enabled with the modulation mode, each arm being used to retract tissue, either along the sample plane (shared direction) or individually (different loads and directions).

8 . The system of claim 1 , where the movement allowed by the robotically controlled arm and the applied load is bound by operational limits that are controlled by the surgeon.

9 . A surgical robotic system, comprising:

first and second robotic arms configured for robotic positioning of first and second surgical instruments, respectively, in a body cavity, the robotic system configured to measure or receive as input direction and value of forces and/or torques applied by an end effector of each surgical instrument in contact with tissue using input from at least one sensor on the corresponding arm;

at least one surgeon input device for receiving surgeon input, the robotic system configured to control the first robotic arm based on the surgeon input to apply a first force and/or torque to tissue using the first surgical instrument;

wherein the system is operable in a force modulation mode in which the robotic system controls the second robotic arm to apply a second force to the tissue using the second surgical instruments, the system configured to determine the direction and magnitude of the second force and/or torque to be applied based on the direction and magnitude of the first force and/or torque.

10 . The system of claim 9 , further including a third robotic arm configured for robotic positioning of a third surgical instrument based on surgeon input using the at least one surgeon input device.

11 . The system of claim 10 , wherein system includes first and second surgeon input devices, the robotic system configured to control the first robotic arm based on surgeon input using the first surgeon input device, and to control the third robotic arm based on surgeon input using the second surgeon input device.

12 . The system of claim 11 wherein the first and second surgical instruments are traction instruments and the third surgical instrument is an instrument for cutting, separating, or dissecting tissue.

13 . A surgical method comprising:

positioning an end effector of a first surgical instrument carried by a first robotic arm in engagement with tissue in a body cavity;

applying a force having a direction and magnitude to the tissue using the end effector; and

controlling movement of the first robotic arm using the robotic surgical system, to maintain the direction and magnitude of the force while the tissue is being treated using a second instrument carried by a second robotic arm.

14 . The method of claim 13 , wherein the first surgical instrument is a retractor and the second surgical instrument is an instrument for dissecting, cutting, sealing, ligating, stapling, or separating tissue.

15 . The method of claim 13 , wherein the first surgical instrument is a retractor and the second surgical instrument is a suture device.

16 . The method of claim 13 , wherein the method further includes:

positioning a second end effector of a second surgical instrument carried by a second robotic arm in engagement with tissue in a body cavity;

applying tension to the tissue by applying a first force to the tissue using the first robotic arm in response to user input using a surgeon input device, and applying a second force to the tissue using the second robotic arm, the direction and magnitude of the second force determined by the robotic system based on the direction and magnitude of the first force.