Microsurgical tool for robotic applications
The disclosed technology includes improved microsurgical tools providing multiple degrees of freedom at the wrist level, including roll, pitch, and grasp DOFs, a tight articulation bending radius, low radial offset, and improved stiffness. Some implementations include an end effector platform moveable along a fixed trajectory on a fictional axle so as not to interfere with a central-axis aligned working channel; a crossed-arm mechanical linkage for articulating an end-effector platform throughout a pitch DOF with an amplified pitch angle; and a partial pulley system to articulate the arms while maximizing pulley radius to shaft diameter, and permitting a constant transmission efficiency to the arms throughout the range of articulation. In some implementations, a tool shaft outer diameter may be smaller than 3 mm; a pitch DOF range may be ±90°, a roll DOF range may be ±180°, and a grasp DOF range may be 30°.
1. A medical tool, comprising:
an elongated body extending between proximal and distal ends; an end effector;
a linkage coupling the distal end of the elongated body to the end effector and configured to articulate the end effector in at least one degree-of-freedom (DOF), the linkage comprising:
a first arm operatively coupled between the distal end of the elongated body and the end effector, the first arm comprises a semicircular portion, and
a second arm operatively coupled between the distal end of the elongated body and the end effector,
wherein the first and second arms are crossed with respect to one another, the first and second arms are configured to move through a range of motion and amplify the range of motion of the first and second arms into articulation of the end effector in the at least one DOF; and
a pull wire configured to follow the semicircular portion of the first arm to permit the semicircular portion to function as a partial pulley attached to the first arm to cause the first arm to rotate when the pull wire is tensioned.
2. The medical tool of claim 1 , wherein:
when the first and second arms travel a range of a first angle, the end effector travels over a range of a second angle, and
the second angle is substantially equal to the first angle multiplied by an amplification factor.
3. The medical tool of claim 2 , wherein the amplification factor is based on geometrical properties of the linkage.
4. The medical tool of claim 1 , wherein:
the first arm is coupled to the elongated body via a hinge,
the elongate body has a central axis, and
the hinge is offset from the central axis.
5. The medical tool of claim 1 , wherein the linkage has a transmission efficiency that is substantially constant.
6. The medical tool of claim 1 , wherein:
the first arm is coupled to the elongated body via a hinge, and the semicircular portion is concentric with the hinge.
7. The medical tool of claim 1 , further comprising:
a platform operatively coupling the end effector to the linkage, wherein:
the first arm comprises a first redirect surface, and
the second arm comprises a second redirect surface.
8. The medical tool of claim 7 , further comprising:
a first force transfer element disposed around the first redirect surface before terminating at the first arm such that pulling the first force transfer element pivots the first arm about a first proximal hinge with a first amplified range of motion; and
a second force transfer element disposed around the second redirect surface before terminating at the second arm such that pulling the second force transfer element pivots the second arm about a second proximal hinge with a second amplified range of motion.
9. The medical tool of claim 1 , wherein the first and second amplified ranges of motion are of the same magnitude in opposite directions.
10. The medical tool of claim 1 , wherein the at least one DOF comprises a pitch DOF.
11. The medical tool of claim 1 , wherein:
the end effector comprises at least one jaw, and
the medical tool further comprises a first tendon coupled to the at least one jaw and tensionable to move the at least one jaw, providing the at least one jaw with a grasping degree of freedom.
12. A medical tool, comprising:
an elongated body having a distal end; an end effector;
an articulable wrist coupling the end effector to the distal end of the elongated body, the wrist comprising:
a first arm operatively coupled between the distal end of the elongated body and the end effector, the first arm comprises a semicircular portion, and
a second arm operatively coupled between the distal end of the elongated body and the end effector,
wherein the first and second arms are crossed with respect to one another, the first and second arms are configured to move through a range of motion and amplify the range of motion of the first and second arms into articulation of the end effector in at least one degree-of-freedom (DOF); and
a pull wire configured to follow the semicircular portion of the first arm to permit the semicircular portion to function as a partial pulley attached to the first arm to cause the first arm to rotate when the pull wire is tensioned.
13. The medical tool of claim 12 , wherein:
when the first and second arms travel a range of a first angle, the end effector travels over a range of a second angle, and
the second angle is substantially equal to the first angle multiplied by an amplification factor.
14. The medical tool of claim 13 , wherein the amplification factor is based on geometrical properties of the wrist.
15. The medical tool of claim 12 , wherein:
the first arm is coupled to the elongated body via a hinge,
the elongate body has a central axis, and
the hinge is offset from the central axis.
16. The medical tool of claim 12 , wherein the linkage has a transmission efficiency that is substantially constant.