Torque sensing in a surgical robotic wrist
A surgical robotic component comprising an articulated terminal portion, the terminal portion comprising: a distal segment having an attachment connected thereto, an intermediate segment, and a basal segment whereby the terminal portion is attached to the remainder of the surgical robotic component. The terminal portion further comprises a first articulation between the distal segment and the intermediate segment, the first articulation permitting relative rotation of the distal segment and the intermediate segment about a first axis, and a second articulation between the intermediate segment and the basal segment, the second articulation permitting relative rotation of the intermediate segment and the basal segment about a second axis. The intermediate segment comprises: a third articulation permitting relative rotation of the distal segment and the basal segment about third and fourth axes, a first torque sensor configured to sense torque about the third axis, and a second torque sensor configured to sense torque about the fourth axis. The first, second and third articulations are arranged such that in at least one configuration of the third articulation the first and second axes are parallel and the third and fourth axes are transverse to the first axis.
1. A surgical robot comprising:
a base; and
an arm extending from the base and terminating at its distal end in a wrist having thereon an attachment configured to attach to a surgical instrument;
wherein:
the arm is articulated by a series of revolute joints along its length, the arm joints comprising, in order running from the base:
i. a first joint having a first axis;
ii. a second joint having a second axis transverse to the first axis;
iii. a third joint having a third axis transverse to the second axis; and
iv. a fourth joint having a fourth axis transverse to the third axis;
the wrist is articulated by a second series of revolute joints along its length such that in a configuration in which the distal end of the arm is collinear with the attachment, the joints of the wrist comprise, in order running towards the attachment:
v. a fifth joint having a fifth axis;
vi. a sixth joint having a sixth axis transverse to the fifth axis; and
vii. a seventh joint having a seventh axis transverse to both the fifth and sixth axes.
2. A surgical robot as claimed in claim 1 , wherein the wrist further comprises a first torque sensor configured to sense torque about the fifth axis.
3. A surgical robot as claimed in claim 2 , wherein the wrist further comprises a second torque sensor configured to sense torque about the sixth axis.
4. A surgical robot as claimed in claim 3 , the surgical robot further comprising a third torque sensor configured to sense torque about the seventh axis.
5. A surgical robot as claimed in claim 4 , wherein the wrist comprises an eighth revolute joint between the fifth joint and the fourth joint, the axis of the eighth joint being transverse to both the fifth and sixth axes.
6. A surgical robot as claimed in claim 5 , the surgical robot further comprising a fourth torque sensor configured to sense torque about the eighth axis.
7. A surgical robot as claimed in claim 5 , wherein in one configuration of the fifth and sixth joints, the eighth axis and the seventh axis are parallel.
8. A surgical robot as claimed in claim 5 , wherein in one configuration of the fifth and sixth joints, the eighth axis and the seventh axis are collinear.
9. A surgical robot as claimed in claim 5 , wherein the first to eighth joints are the only means of articulation of the arm.
10. A surgical robot as claimed in claim 1 , wherein the fifth and sixth axes intersect.
11. A surgical robot as claimed in claim 1 , comprising an additional revolute joint between the first joint and the base, the additional joint having an additional axis perpendicular to the first axis.
12. A surgical robot as claimed in claim 1 , comprising an additional revolute joint between the second joint and the third joint, the additional joint having an axis transverse to the first axis.
13. A surgical robot as claimed in claim 1 , wherein the fifth and sixth joints are constituted by a joint structure which acts as a spherical joint, and which as an intermediate member capable of moving about a first joint with respect to a basal segment of the wrist and about a second joint with respect to a distal segment of the wrist.
14. A surgical robot as claimed in claim 1 , wherein the first to seventh joints are the only means of articulation of the arm.
15. A surgical robot as claimed in claim 1 , further comprising a surgical instrument attached to the attachment.
16. A surgical robot as claimed in claim 15 , wherein the surgical instrument extends in a direction substantially along the seventh axis.