2D-image guided robotic distal locking system
A 2D image-guided surgical robot system for distal locking operations includes surgical image acquisition equipment, a robot arm, a robot end effector attached to the robot arm, and a remote operation workstation. To perform a distal locking operation, the position of the image acquisition device is adjusted to obtain a round outline of a lockhole in the image. A distortion correction is performed. The position of the target lockhole is assigned by a user through the GUI of the remote operation workstation, and the remote operation workstation calculates a robot motion quantity using image feedback control law and moves the robot accordingly. The “image-and-move” procedure is repeated several times until the drill guide is accurately aligned to the lockhole, then the distal locking operation is accomplished by first drilling a guide hole using a guide wire through the drill guide, and then screwing a locking screw through the guide hole.
1. An end effector for a surgical robot arm comprising:
(1) a connector arm having a proximal end and a distal end, wherein the proximal end is reversibly securable to the surgical robot;
(2) a registration device secured to the distal end of the connector arm comprising:
(a) a base made from an X-ray transparent material, the base comprising an inner portion, an outer portion, and a medial portion, wherein the medial portion extends between and connects the inner portion and the outer portion; and
(b) at least 8 beads made from a material opaque to X-rays, wherein the beads comprise a first set of beads and a second set of beads, the first set of beads being attached to the inner portion of the base and the second set of beads being attached to the outer portion of the base, wherein the first set of beads has a first diameter and the second set of beads has a second diameter, and wherein the first diameter is different than the second diameter; and
(3) a drill guide secured to the distal end of the connector arm,
wherein centers of the first set of beads are in a first plane and are arranged to form vertices of a convex polygon in the first plane, and wherein centers of the second set of beads are in a second plane and are arranged to form vertices of a convex polygon in the second plane, the second plane being a different plane than the first plane, wherein the first and second planes are parallel,
wherein the first set of beads can be grouped into pairs of beads, wherein lines extending between each of the pairs of beads cross at a first crossing point in the first plane, and wherein normalized distances between each of the first set of beads and the first crossing point are different,
wherein the second set of beads can be grouped into pairs of beads, wherein lines extending between each of the pairs of beads cross at a second crossing point in the second plane, and wherein normalized distances between each of the second set of beads and the second crossing point are different,
wherein the normalized distance is a ratio of the distance between a first bead of a pair of beads and a crossing point to the distance between the first bead and the second bead of the pair of beads, and
wherein the drill guide extends along a longitudinal axis, and the longitudinal axis extends through the inner portion of the base at a right angle to the first and second planes.
2. The end effector for a surgical robot arm of claim 1 , wherein the first set of beads has a diameter that is smaller than the diameter of the second set of beads.
3. The end effector for a surgical robot arm of claim 2 , wherein the diameter of the second set of beads is between 0.4 and 1.5 times longer than the diameter of the first set of beads.
4. The end effector for a surgical robot arm of claim 1 , wherein the second set of beads has a diameter that is smaller than the diameter of the first set of beads.
5. The end effector for a surgical robot arm of claim 4 , wherein the diameter of the first set of beads is between 0.4 and 1.5 times longer than the diameter of the second set of beads.
6. The end effector for a surgical robot arm of claim 1 , wherein the medial portion of the base is frustoconical in shape.
7. The end effector for a surgical robot arm of claim 1 , wherein the medial portion of the base comprises a right side portion and a left side portion, and wherein the right side portion does not directly contact the left side portion.
8. A method for performing a distal locking operation with a surgical robot system, wherein the robot system comprises a robot arm with at least 3 translational degrees of freedom and 2 rotational degrees of freedom, the end-effector of claim 1 attached to the robot arm, 2D X-ray image acquisition device, an image distortion correction device and a display, comprising the steps of:
a) adjusting the position and orientation of the 2D X-ray image acquisition device until a target lockhole appears in a first 2D X-ray image obtained by the X-ray image acquisition device;
b) correcting image distortion by:
mounting the image distortion correction device on the 2D X-ray image acquisition device of the robotic surgery system;
collecting a second 2D X-ray image and then correcting the image distortion in the first 2D X-ray image; and
unmounting the image distortion correction device from the 2D X-ray image acquisition device;
c) moving the robot end-effector of claim 1 into the field of view of the 2D X-ray image acquisition device;
d) collecting a third image, wherein the image depicts the robot end effector, and displaying it on the display, wherein the beads on the robot end-effector appear in the third image, and marking the target lockhole on the displayed image;
e) moving the robot according to the position of the beads and the marked target lockhole in the 2D X-ray image;
f) collecting a fourth image and calculating the alignment error between the drill guide and the lockhole;
g) if the alignment error calculated in step f) is larger than a preset threshold, repeating step e) and step f); and
h) drilling the guide hole for distal locking through the drill guide with a guide wire and then accomplishing the distal locking by screwing a locking screw along the guide hole.