Load cells in an instrument drive

Patent metadata

Field	Value
Publication number	US-10653487-B2
Application number	US-201615563839-A
Country	US
Kind code	B2
Filing date	Apr 20, 2016
Priority date	Apr 21, 2015
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

A drive unit for providing drive from a robot arm to an instrument, the drive unit comprising: a plurality of drive elements for engaging corresponding elements of the instrument, each drive element being movable along a drive axis and the drive axes of each of the drive elements being substantially parallel to each other; and a load cell structure comprising a plurality of deflectable bodies coupled to the drive elements for sensing load on the drive elements parallel to their drive axes, and a frame comprising an integral member supporting the deflectable bodies in such a way as to isolate each deflectable body from load applied to the or each other deflectable body.

First claim

The invention claimed is:

1. A drive unit for providing drive from a robot arm to an instrument, the drive unit comprising:
a load cell structure comprising a perimeter formed by a plurality of rings, wherein the plurality of rings are one-piece, monolithically formed with each other;
wherein each of the plurality of rings is connected to a respective flange by a respective deflectable web, wherein each respective flange defines a respective through-hole;
wherein each respective through-hole has a respective lead screw disposed therethrough.

2. A drive unit as claimed in claim 1 , wherein:
each respective lead screw has a respective follower nut threadably engaged therewith;
each respective follower nut is coupled to a respective drive tab.

3. A drive unit as claimed in claim 2 , wherein:
each respective lead screw is driven by a respective motor; and
a rigid housing supporting the respective motors, the housing comprising two components, a first component to which the respective motors are attached and a second component comprising apertures within which the respective drive tabs are respectively movable, the load cell structure being sandwiched between the first component and the second component.

4. A drive unit as claimed in claim 3 , wherein each respective follower nut interacts with a respective wall or rib of the second component of the housing to prevent rotation of the respective follower nut.

5. A drive unit as claimed in claim 4 , wherein:
each respective lead screw is connected to the respective motor by a respective splined coupling, each respective splined coupling being configured to permit axial play between the respective motor and the respective lead screw.

6. A drive unit as claimed in claim 1 , wherein each respective lead screw is supported by a respective at least one bearing configured to permit the respective lead screw to rotate relative to the load cell structure.

7. A drive unit as claimed in claim 6 , wherein each respective at least one bearing includes two bearings with each of the two bearings disposed on a respective one of opposed sides of the load cell structure.

8. A drive unit as claimed in claim 1 , wherein:
each respective lead screw defines a respective axial axis, the respective axial axes being parallel to each other;
each respective deflectable web is perpendicular to the respective axial axes of the respective lead screws.

9. A drive unit as claimed in claim 1 , wherein the plurality of rings is substantially rigid.

10. A drive unit as claimed in claim 1 , wherein the plurality of rings is one-piece, monolithically formed with the respective deflectable webs.

11. A drive unit as claimed in claim 1 , wherein each respective deflectable web has a respective strain gauge disposed thereon, the respective strain gauge configured to sense deflection of the respective deflectable web.

12. A surgical robot comprising the drive unit as claimed in claim 1 .

13. A surgical robot as claimed in claim 12 , wherein the drive unit is disposed at a distal end of the robot arm.

14. A surgical robot comprising the drive unit as claimed in claim 2 , wherein the instrument comprises corresponding elements being engaged with the respective drive tabs so as to be driven thereby.

Assignees

• Cmr Surgical Ltd

Inventors

• Marshall Keith
• Phoolchund Nikki Priyam Su-Ling
• Jackson Thomas Bates

Classifications

• G01L1/2231

  the supports being disc- or ring-shaped, adapted for measuring a force along a single direction · CPC title

• A61B2017/00477

  Coupling (A61B2017/0046 takes precedence) · CPC title

• B25J13/085

  Force or torque sensors (B25J13/082, B25J13/084 take precedence) · CPC title

• G01L1/2237

  the direction being perpendicular to the central axis · CPC title

• G01L5/0019

  by using strain gages, piezoelectric, piezo-resistive or other ohmic-resistance based sensors · CPC title