Torque-Based Catheter Articulation With Feedback for Tip Accuracy
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Solution Overview
Problem
Existing robotic surgical systems face inaccuracies in predicting catheter tip movement due to unmodeled anatomical constraints and external forces, leading to discrepancies between calculated and actual kinematic functions during minimally invasive procedures.
Innovation Solution
A robotic surgical system that utilizes closed-loop feedback and torque-based control to adjust motor current and kinematic parameters, incorporating torque sensors to measure actual motor torque and correct for discrepancies, enabling precise catheter articulation by translating positional data into pull-wire tension values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If kinematic modeling is used to predict catheter tip movement, then catheter positioning can be controlled, but inaccuracies occur due to unmodeled anatomical constraints and external forces
Solution Approach 1:
The patent implements a closed-loop feedback system where torque sensors measure actual motor torque, and this feedback is used to adjust the control algorithm. The system compares predicted catheter position with actual position and uses torque feedback to compensate for unmodeled anatomical constraints and external forces, thereby improving prediction accuracy and reducing discrepancies between calculated and actual kinematic functions.
Solution Approach 2:
The patent dynamically adjusts kinematic parameters based on measured torque values. The control algorithm modifies the relationship between pull-wire displacement and catheter articulation by incorporating torque-dependent corrections. This allows the system to adapt to varying anatomical conditions and external forces, improving the accuracy of catheter tip movement prediction under different operating conditions.
2Ease of operation
If pull-wire displacement is used to control catheter articulation, then catheter movement can be achieved, but unanticipated anatomical constraints affect articulation accuracy
Solution Approach 1:
The system uses torque sensors to measure actual motor torque and feeds this information back to the control algorithm. This feedback loop allows the system to detect when anatomical constraints are acting on the catheter and automatically adjust the control commands to compensate for these constraints, maintaining both ease of operation and prediction accuracy.
Solution Approach 2:
The patent replaces purely displacement-based mechanical control with a torque-based control system. Instead of relying solely on pull-wire displacement to achieve desired articulation, the system uses torque measurements to understand the actual mechanical state of the catheter and adjusts control commands accordingly, substituting mechanical displacement control with intelligent torque-based control.
3Device complexity
If external forces are not accounted for in kinematic modeling, then the system remains simple, but actual catheter motion deviates from predicted motion
Solution Approach 1:
The system incorporates torque feedback from sensors that measure actual motor torque in real-time. This feedback mechanism allows the control algorithm to detect and compensate for external forces acting on the catheter without requiring complex pre-programmed models of all possible anatomical constraints. The system adapts to external forces dynamically through feedback, maintaining position accuracy while keeping the base kinematic model relatively simple.
Data Source
AI summary
A robotic surgical system configured for the articulation of a catheter comprises an input device, a control computer, and an instrument driver having at least one motor for displacing the pull-wire of a steerable catheter wherein the control computer is configured to determine the desired motor torque or tension of the pull-wire of a catheter based on user manipulation of the input device. The control computer is configured to output the desired motor torque or tension of the pull-wire to the instrument driver, whereby at least one motor of the instrument driver implements the desired motor torque to cause the desired pull-wire tension to articulate the distal tip of the catheter.