Manipulator Null-Space Motion Control for Surgical Arms
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Solution Overview
Problem
Current robotic surgical systems face challenges in limiting unnecessary movement of manipulator arms during tasks while increasing the range of motion and maintaining dexterity, often resulting in excessive mechanical complexity and cost.
Innovation Solution
The system employs a manipulator arm with a plurality of joints providing sufficient degrees of freedom, a processor to calculate coordinated joint movements, and weighted joint velocities to achieve desired end effector movements by utilizing a pseudo-inverse solution of a Jacobian matrix, emphasizing motion in a null-space direction to reduce unnecessary movement and enhance dexterity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional redundant joints are added to manipulator arms to increase range of motion and configurations, then the available configurations and range of motion are expanded, but the manipulators exhibit excessive movement outside the patient and the mechanical complexity increases
Solution Approach 1:
The patent replaces mechanical constraints with software-based control. Instead of using complex mechanical linkages to physically constrain manipulator movement, the system uses a processor to calculate and enforce virtual constraints through software control of the joints, achieving the same effect with reduced mechanical complexity
Solution Approach 2:
The system dynamically adjusts joint parameters (velocities, positions) based on real-time calculations. The processor continuously computes optimal joint configurations that satisfy task requirements while minimizing unnecessary movement, adapting the manipulator behavior without changing its physical structure
2Reliability
If software control is used to restrain pivotal motion at the insertion site, then safety is improved, but the manipulators become difficult to manually set up and the control complexity increases
Solution Approach 1:
The system performs self-setup through automated calculations. The processor automatically determines the optimal manipulator configurations and joint parameters based on the surgical task requirements, eliminating the need for manual setup by operators and reducing the skill barrier for system configuration
3Adaptability or versatility
If the range of surgeries is expanded and the range of motion is increased, then adaptability is improved, but the challenges associated with manipulator motion outside the body increase
Solution Approach 1:
The patent creates a universal control framework that handles multiple surgical tasks and manipulator configurations through a single software-based approach. The same processor-based constraint enforcement mechanism works across different surgical procedures and manipulator types, providing adaptability without proportionally increasing control complexity
Data Source
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AI summary
Devices, systems, and methods for providing commanded movement of an end effector of a manipulator while providing a desired movement of one or more joints of the manipulator. Methods include calculating weighted joint velocities using a weighting matrix within the joint space to anisotropically emphasize joint movement within a null-space to provide the desired movement of a first set of joints. Methods may include calculating joint velocities that achieve the desired end effector movement using a pseudo-inverse solution and adjusting the calculated joint velocities using a potential function gradient within the joint space corresponding to the desired movement of the first set of joints. Methods may include use of a weighted pseudo-inverse solution and also an augmented Jacobian solution. One or more auxiliary movements may also be provided using joint velocities calculated from the pseudo-inverse solution. Various configurations for systems utilizing such methods are provided herein.