Virtual Remote Center Control for Robotic Surgical Ports
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Solution Overview
Problem
Robotic systems without a mechanical remote center of motion (RCM) in minimally invasive surgery struggle to perform spherical rotation of surgical instruments around anatomical ports without exerting translational forces, which can harm patients.
Innovation Solution
A robotic surgical system with a robot controller that defines and aligns a virtual RCM using string potentiometers or optical shape sensing fibers to ensure spherical rotation of surgical instruments relative to anatomical ports without translational forces, allowing for precise navigation and alignment with anatomical regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a robotic device is used to control surgical instruments during minimally invasive surgery, then surgical precision and control are improved, but translational forces are exerted on the anatomical ports which can cause patient injury
Solution Approach 1:
The patent replaces the mechanical RCM constraint with a virtual RCM defined through coordinate transformations and control algorithms. The robot controller calculates a virtual RCM point in the robot's coordinate frame and uses software-based control to constrain motion to spherical rotation around this point, eliminating the need for mechanical constraint structures that would otherwise be required.
Solution Approach 2:
The patent introduces a virtual RCM point as an intermediary concept between the robot's coordinate system and the anatomical port location. This virtual point serves as the focal point for spherical rotation calculations, allowing the controller to mediate between the robot's degrees of freedom and the surgical requirement of port-fixed rotation without direct mechanical contact or constraint at the port site.
2Reliability
If a mechanical remote center of motion is implemented in the robot design, then spherical rotation without translational forces is achieved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical RCM constraint with a virtual RCM defined through coordinate transformations and control algorithms. The robot controller calculates a virtual RCM point in the robot's coordinate frame and uses software-based control to constrain motion to spherical rotation around this point, eliminating the need for mechanical constraint structures that would otherwise be required.
Solution Approach 2:
The patent dynamically calculates and updates the virtual RCM position based on the robot's current pose and the desired anatomical port location. By changing the parameter definition from a fixed mechanical constraint to a computationally defined point that can be repositioned through coordinate transformations, the system achieves adaptability without mechanical reconfiguration.
3Object-affected harmful factors
If a virtual remote center of motion is defined and navigated, then translational forces are eliminated, but control complexity increases
Solution Approach 1:
The patent replaces the mechanical RCM constraint with a virtual RCM defined through coordinate transformations and control algorithms. The robot controller calculates a virtual RCM point in the robot's coordinate frame and uses software-based control to constrain motion to spherical rotation around this point, eliminating the need for mechanical constraint structures that would otherwise be required.
Solution Approach 2:
The patent implements a feedback control mechanism where the robot controller continuously monitors the robot's pose and the position of the virtual RCM point, calculating the necessary spherical rotation commands to maintain alignment. This closed-loop control ensures that the surgical instrument rotates around the virtual RCM without exerting translational forces, providing real-time correction to maintain the constraint.
4Reliability
If the robot controller defines and aligns virtual RCM with anatomical ports, then patient safety is improved, but navigation and alignment complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the robot controller continuously monitors the robot's pose and the position of the virtual RCM point, calculating the necessary spherical rotation commands to maintain alignment. This closed-loop control ensures that the surgical instrument rotates around the virtual RCM without exerting translational forces, providing real-time correction to maintain the constraint.
Solution Approach 2:
The patent creates a universal virtual RCM definition method that can be applied to any robot configuration and any anatomical port location. The coordinate transformation approach provides a general framework that works across different surgical scenarios, robot types, and port positions, eliminating the need for scenario-specific mechanical adaptations while maintaining patient safety.
Data Source
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AI summary
A robotic surgical system employs a surgical instrument (20), a robot (40) for navigating the surgical instrument (20) relative to an anatomical region (10) within a coordinate system (42) of the robot (40), and a robot controller (43) for defining a remote center of motion for a spherical rotation of the surgical instrument (20) within the coordinate system (42) of the robot (40) based on a physical location within the coordinate system (42) of the robot (40) of a port (12) into the anatomical region (10). The definition of the remote center of rotation is used by the robot controller (43) to command the robot (40) to align the remote center of motion of the surgical instrument (20) with the port (12) into the anatomical region (10) for spherically rotating the surgical instrument (20) relative to the port (12) into the anatomical region (10).