Micro-force guided cooperative control for surgical manipulation of delicate tissue
A method and system for micro-force guided cooperative control that assists the operator in manipulating tissue in the direction of least resistance. A tool holder receives a surgical tool adapted to be held by a robot and a surgeon. A first sensor measures interaction forces between a tip of the surgical tool and tissue of a region of interest. A second sensor measures interaction forces between the surgeon and a handle to the surgical tool. A data processor is configured to perform an algorithm to actively guide the surgical tool by creating a bias towards a path of least resistance and limit directional tool forces of the surgical tool as a function of handle input forces and tip forces. This function offers assistance to challenging retinal membrane peeling procedures that require a surgeon to delicately delaminate fragile tissue that is susceptible to hemorrhage and tearing due to undesirable forces.
1. A method of cooperative control of a surgical tool, comprising:
providing a surgical tool to be manipulated during an operation;
measuring interaction forces between the surgical tool and tissue of a region of interest;
measuring interaction forces between a surgeon and a handle of the surgical tool; and
actively guiding, by a cooperatively controlled robot, the surgical tool by creating a direction-dependent bias in the response of the cooperatively controlled robot to said measured interaction forces between said surgeon and said handle of said surgical tool based on said measured interaction forces between said surgical tool and tissue of said region of interest,
wherein actively guiding the surgical tool comprises applying a limit on directional tool forces according to
x
.
lim
=
x
.
(
f
lim
-
f
t
l
lim
)
,
wherein {dot over (x)} is the velocity, f lim is a limit of the interaction forces between a tip of the surgical tool and the tissue of a region of interest, f t is the measured interaction forces between the tip of the surgical tool and the tissue of a region of interest, and wherein a virtual spring of length l lim is used to ensure stability at the limit boundary.
2. The method of cooperative control of a surgical tool according to claim 1 , wherein directional tool force limits are redistributed when the surgeon changes a direction of the surgical tool.
3. The method of cooperative control of a surgical tool according to claim 1 , wherein the limit of the interaction forces between the tip of the surgical tool and the tissue of the region of interest is based on biological data.
4. The method of cooperative control of a surgical tool according to claim 1 , wherein the limit of the interaction forces between the tip of the surgical tool and the tissue of the region of interest is based on sensor data gathered during tissue manipulation.
5. The method of cooperative control of a surgical tool according to claim 4 , wherein the tissue is eye tissue.
6. The method of cooperative control of a surgical tool according to claim 1 , further comprising using the method to perform a blunt tissue dissection.
7. The method of cooperative control of a surgical tool according to claim 1 , further comprising dynamically updating virtual fixtures in robot assisted manipulation.
8. A method of cooperative control of a surgical tool, comprising:
providing a surgical tool to be manipulated during an operation;
measuring interaction forces between the surgical tool and tissue of a region of interest;
measuring interaction forces between a surgeon and a handle of the surgical tool; and
actively guiding, by a cooperatively controlled robot, the surgical tool by creating a direction-dependent bias in the response of the cooperatively controlled robot to said measured interaction forces between said surgeon and said handle of said surgical tool based on said measured interaction forces between said surgical tool and tissue of said region of interest,
wherein creating a direction-dependent bias comprises enforcing a minimum velocity according to
{dot over (x)} min =k p (1− r t s min )f h ,
where k p is a gain of the measured interaction forces between the tip of the surgical tool and the tissue of a region of interest; r t =|f t |/∥f t ∥, where f t is the measured interaction forces between a tip of the surgical tool and the tissue of a region of interest; s min is a sensitivity of minimization that sets a ratio of the handle force to be locally minimized; and f h is the measured interaction forces between the surgeon and the handle to the surgical tool.
9. A cooperative control robotic system, comprising:
a tool holder for receiving a surgical tool;
a first sensor for measuring interaction forces between the surgical tool and tissue of a region of interest;
a second sensor for measuring interaction forces between a surgeon and a handle of the surgical tool; and
a cooperatively controlled robot configured to actively guide the surgical tool by creating a direction-dependent bias in a response of said cooperatively controlled robot to said measured interaction forces between said surgeon and said handle of said surgical tool based on said measured interaction forces between said surgical tool and tissue of said region of interest,
wherein the cooperatively controlled robot is configured to actively guide the surgical tool by applying a limit on directional tool forces according to
x
.
lim
=
x
.
(
f
lim
-
f
t
l
lim
)
,
wherein {dot over (x)} is the velocity, f lim is a limit of the interaction forces between a tip of the surgical tool and the tissue of a region of interest, f t is the measured interaction forces between the tip of the surgical tool and the tissue of a region of interest, and wherein a virtual spring of length l lim is used to ensure stability at the limit boundary.
10. The cooperative control robotic system according to claim 9 , wherein directional tool force limits are redistributed when the surgeon changes a direction of the surgical tool.
11. The cooperative control robotic system according to claim 9 , wherein the limit of the interaction forces between the tip of the surgical tool and the tissue of the region of interest is based on biological data.
12. The cooperative control robotic system according to claim 9 , wherein the limit of the interaction forces between the tip of the surgical tool and the tissue of the region of interest is based on sensor data gathered during tissue manipulation.
13. The cooperative control robotic system according to claim 12 , wherein the tissue is eye tissue.
14. The cooperative control robotic system according to claim 9 , wherein the system is used to perform a blunt tissue dissection.
15. The cooperative control robotic system according to claim 9 , wherein the cooperatively controlled robot is configured to dynamically update virtual fixtures in robot assisted manipulation.
16. A cooperative control robotic system, comprising:
a tool holder for receiving a surgical tool;
a first sensor for measuring interaction forces between the surgical tool and tissue of a region of interest;
a second sensor for measuring interaction forces between a surgeon and a handle of the surgical tool; and
a cooperatively controlled robot configured to actively guide the surgical tool by creating a direction-dependent bias in a response of said cooperatively controlled robot to said measured interaction forces between said surgeon and said handle of said surgical tool based on said measured interaction forces between said surgical tool and tissue of said region of interest,
wherein the cooperatively controlled robot is configured to create a direction-dependent bias by enforcing a minimum velocity according to
{dot over (x)} min =k p (1− r t s min )f h ,
where k p is a gain of the measured interaction forces between the tip of the surgical tool and the tissue of a region of interest; r t =|f t |/∥f t ∥, where f t is the measured interaction forces between a tip of the surgical tool and the tissue of a region of interest; s min is a sensitivity of minimization that sets a ratio of the handle force to be locally minimized; and f h is the measured interaction forces between the surgeon and the handle to the surgical tool.