Tele-Surgical Manipulator Null-Space Joint Motion Cancellation

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Solution Overview

Problem

Current surgical robotic systems face challenges in limiting unnecessary movement of manipulator arms during tasks while increasing the range of motion within the patient, which can lead to collisions and require complex manual setup, increasing training needs and mechanical complexity.

Innovation Solution

The system employs highly configurable surgical robotic manipulators with additional redundant joints that allow for reconfiguration and collision avoidance by canceling movement of non-moving joints, using a processor to calculate coordinated joint movements and allowing movement of locked joints for auxiliary tasks, thereby enhancing dexterity and reducing mechanical complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If redundant joints are added to increase range of motion and dexterity, then the manipulator can perform auxiliary tasks and avoid collisions, but the device complexity and mechanical structure become more complex

Engineering Contradiction:
Improverange of motionVSAvoidmechanical complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The redundant joints in the manipulator arm are designed to serve multiple functions: they enable collision avoidance by adjusting arm configuration, facilitate repositioning without moving the end effector, and provide additional degrees of freedom for auxiliary tasks. This multi-functionality allows the system to handle diverse surgical requirements with a single integrated structure, resolving the contradiction between enhanced adaptability and increased mechanical complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically activates or deactivates specific joints based on task requirements. During precision surgical tasks, certain joints are locked to simplify the mechanical system and improve stability. During repositioning or collision avoidance maneuvers, these same joints are unlocked to provide additional flexibility. This dynamic configuration allows the manipulator to adapt its complexity level to match the operational demands.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If redundant joints are added to allow reconfiguration and collision avoidance, then the manipulator can perform auxiliary tasks, but the setup and training requirements increase

Engineering Contradiction:
Improvereconfiguration capabilityVSAvoidsetup complexity
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The manipulator system performs self-reconfiguration using its own redundant joints and control algorithms. When collision avoidance or repositioning is needed, the system autonomously calculates the required joint adjustments and executes them without requiring external manual intervention or complex setup procedures. This self-service capability reduces the burden on operators and simplifies the overall setup process despite the presence of redundant joints.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The control system continuously monitors the manipulator's position, orientation, and environmental obstacles, using this feedback to dynamically adjust joint configurations. Sensors detect potential collisions or suboptimal positions, and the controller automatically computes corrective joint movements. This closed-loop feedback mechanism eliminates the need for manual reconfiguration and reduces training requirements, as the system adapts autonomously based on real-time conditions.

Inventive Principle:
Principle #23Feedback

3Reliability

If movement of joints is canceled to limit unnecessary movement, then collisions are reduced, but the control system becomes more complex

Engineering Contradiction:
Improvecollision avoidanceVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system replaces complex mechanical constraint mechanisms with software-based control algorithms that calculate and execute joint movement cancellation. Instead of using physical stops, locks, or mechanical guides to prevent unnecessary joint motion, the control system uses computational models to determine which joint movements should be canceled based on the current task and environmental context. This substitution of mechanical complexity with intelligent control reduces overall system complexity while maintaining collision avoidance capabilities.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The control system dynamically adjusts joint movement parameters (such as velocity, position, or activation state) based on real-time task requirements and environmental conditions. When a collision risk is detected or during precision tasks, the system modifies joint movement parameters to cancel potentially harmful motions while allowing beneficial movements to proceed. This parameter-based control approach provides flexible collision avoidance without requiring complex mechanical intervention systems.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2884937B1Systems for cancellation of joint motion using the null-space
Publication Date: 2022.10.05 INTUITIVE SURGICAL OPERATIONS INC
  • EP2884937B1 patent drawingFigure 1A
  • EP2884937B1 patent drawingFigure 1B
  • EP2884937B1 patent drawingFigure 2~3

AI summary

Devices, systems, and methods for cancelling movement one or more joints of a tele-surgical manipulator to effect manipulation movement of an end effector. Methods include calculating movement of joints within a null-perpendicular space to effect desired end effector movement while calculating movement of one or more locked joints within a null-space to cancel the movement of the locked joints within the null-perpendicular-space. Methods may further include calculating movement of one or more joints to effect an auxiliary movement or a reconfiguration movement that may include movement of one or more locked joints. The auxiliary and reconfiguration movements may be overlaid the manipulation movement of the joints to allow movement of the locked joints to effect the auxiliary movement or reconfiguration movement, while the movement of the locked joints to effect manipulation is canceled. Various configurations for devices and systems utilizing such methods are provided herein.