Torque-Based Catheter Articulation With Pull-Wire Tension Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing robotic catheter systems face inaccuracies in predicting and controlling the movement of the catheter tip due to unmodeled anatomical constraints and external forces, leading to discrepancies between calculated and actual kinematic functions.
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 adapt electrical current, ensuring precise catheter articulation by translating positional data into pull-wire tension values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If kinematic modeling is used to predict catheter tip movement, then catheter control is simplified, but accuracy deteriorates due to unmodeled anatomical constraints
Solution Approach 1:
The system continuously measures actual catheter tip position using sensors (optical, electromagnetic, or ultrasonic) and compares it with the predicted position from kinematic modeling. The difference (error signal) is fed back to the control system, which adjusts the pull-wire actuation commands to compensate for anatomical constraints and achieve accurate catheter positioning.
2Device complexity
If pull-wire actuation is used for catheter articulation, then device complexity is reduced, but control precision deteriorates due to unmodeled constraints
Solution Approach 1:
Torque sensors measure the actual torque required to actuate the pull-wires, and position sensors measure the actual catheter tip position. This feedback information is used to adjust the control algorithm, compensating for unmodeled anatomical constraints while maintaining the simplicity of the pull-wire actuation mechanism.
Solution Approach 2:
The system dynamically adjusts control parameters (such as the relationship between pull-wire displacement and catheter articulation) based on real-time torque measurements and anatomical constraints detected during the procedure, allowing the same simple mechanism to achieve high precision under varying conditions.
3Measurement precision
If closed-loop feedback is implemented, then catheter positioning accuracy is improved, but system complexity increases
Solution Approach 1:
The control system uses feedback from torque sensors and position sensors to continuously correct positioning errors. By implementing this feedback mechanism, the system achieves high positioning accuracy while the added complexity is managed through algorithmic approaches rather than mechanical complexity.
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.