Robotic imaging system with force-based collision avoidance mode

Patent metadata

Field	Value
Publication number	US-12390930-B2
Application number	US-202318112597-A
Country	US
Kind code	B2
Filing date	Feb 22, 2023
Priority date	Mar 1, 2022
Publication date	Aug 19, 2025
Grant date	Aug 19, 2025

Abstract

A robotic imaging system includes a camera configured to obtain one or more images of a target site. A robotic arm is operatively connected to the camera, the robotic arm being adapted to selectively move the camera in a movement sequence. A force-based sensor is configured to detect and transmit sensor data related to at least one of force and/or torque imparted by a user for moving the camera. The system includes a controller configured to receive the sensor data. The controller has a processor and tangible, non-transitory memory on which instructions are recorded. The controller is adapted to selectively execute a collision avoidance mode, including applying a respective correction force to modify the movement sequence when the camera and/or the robotic arm enter a predefined buffer zone.

First claim

What is claimed is:

1. A robotic imaging system comprising:
a camera configured to record one or more images of a target site;
a robotic arm operatively connected to the camera, the robotic arm being adapted to selectively move the camera in a movement sequence, the robotic arm including one or more joints;
a force-based sensor configured to detect and transmit sensor data related to at least one of force and/or torque imparted by a user for moving the camera;
a controller configured to receive the sensor data, the controller having a processor and tangible, non-transitory memory on which instructions are recorded;
wherein the controller is adapted to selectively execute a collision avoidance mode, including applying a respective correction force to modify the movement sequence when at least one of the camera and the robotic arm enter a predefined buffer zone, the predefined buffer zone being within a delta value of at least one keep-out zone; and
wherein the controller is adapted to apply the respective correction force to push at least one of the camera and the robotic arm away from the at least one keep-out zone.

2. The robotic imaging system of claim 1 , wherein:
the camera is a stereoscopic camera configured to record a left image and a right image for producing at least one stereoscopic image of the target site.

3. The robotic imaging system of claim 1 , wherein:
the force-based sensor includes a six-degrees-of-freedom haptic force-sensing device.

4. The robotic imaging system of claim 1 , wherein:
the controller is adapted to calculate the respective correction force using a closed-loop control module, including at least one of a proportional-integral controller, a proportional-derivative controller and a proportional-integral-derivative controller.

5. The robotic imaging system of claim 1 , wherein the controller is adapted to calculate the respective correction force for one or more checkpoints each having a respective position and respective speed along a first direction.

6. The robotic imaging system of claim 5 , further comprising:
a head unit for housing the camera;
a coupling plate mechanically coupling the head unit to the robotic arm, the head unit being operatively connected to a cart; and
wherein the one or more checkpoints are located on at least one of the head unit, the coupling plate and the robotic arm.

7. The robotic imaging system of claim 5 , wherein:
the controller is adapted to calculate the respective correction force using a proportional-derivative controller as: F=[K p (b−x)+K d (0−{dot over (x)})], with F denoting the respective correction force, b denoting a respective buffering distance to the at least one keep-out zone, x and i denoting the respective position and respective speed of the one or more checkpoints, and K p and K d denoting respective tunable gain factors of the proportional-derivative controller.

8. The robotic imaging system of claim 1 , wherein the controller is adapted to execute a joint limit calculation, the respective correction force including a force contribution from the joint limit calculation.

9. The robotic imaging system of claim 8 , wherein executing the joint limit calculation includes:
determining a respective torque for the at least one joint, via a closed-loop module; and
converting the respective torque to a respective tool force using a transpose of a Jacobian matrix, the force contribution being based on a sum of the respective tool force for each of the one or more joints.

10. The robotic imaging system of claim 1 , further comprising:
a cart operatively connected to the robotic arm;
wherein the respective correction force includes a force contribution from a cart limit calculation;
wherein the controller is adapted to execute the cart limit calculation, including:
calculating a respective spherical distance and a respective speed of one or more checkpoints from a surface of the cart;
obtaining a radial force when the respective spherical distance is below a predefined threshold; and

wherein the force contribution is obtained as the radial force multiplied by a fraction.

11. The robotic imaging system of claim 10 , wherein:
the surface of the cart is modelled as a sphere and the respective spherical distance (r) is obtained as:

r
=

(

w
0

-

s
0

)

2

+

(

w
1

-

s
1

)

2

+

(

w
2

-

s
2

)

2

,

with (w 0 , w 1 , w 2 ) denoting respective coordinates of the one or more checkpoints and (s 0 , s 1 , s 2 ) denoting the respective coordinates of a center of the sphere.

12. The robotic imaging system of claim 11 , wherein the respective speed ({dot over (r)}) is obtained based in part on the respective coordinates of the center of the sphere and a time derivative of the respective coordinates of the one or more checkpoints.

13. The robotic imaging system of claim 12 , wherein the respective speed ({dot over (r)}) is obtained as

r
.

=

w
0

.

(

w
0

-

s
0

)

+

w
1

.

(

Assignees

• Alcon Inc

Inventors

• Terry Patrick

Classifications

• B25J19/023

  including video camera means · CPC title

• B25J15/0019

  End effectors other than grippers · CPC title

• B25J13/084

  Tactile sensors (in general G01L5/16, G01L5/22) · CPC title

• B25J9/1633

  compliant, force, torque control, e.g. combined with position control · CPC title

• B25J9/1607

  Calculation of inertia, jacobian matrixes and inverses · CPC title