Catheter Tension Sensing via Torque Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Robotic catheter systems face challenges in accurately measuring and controlling catheter pullwire tension due to unmodeled constraints and external forces, leading to discrepancies between predicted and actual catheter motion during minimally invasive procedures.
Innovation Solution
A robotic surgical system with a control system that includes a rotary output motor and torque sensors to measure and determine output shaft torque, allowing for precise articulation of catheters by directly measuring torque on the output shaft and converting it into pullwire tension, while also considering drivetrain compliance and reaction forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque sensors are added to measure output shaft torque, then measurement precision of pullwire tension is improved, but device complexity increases
Solution Approach 1:
A torque sensor is introduced as an intermediary component between the motor and the pullwire system. The torque sensor measures the torque applied to the output shaft, which indirectly provides information about the pullwire tension. This intermediary approach allows for precise tension measurement without directly measuring the pullwire force, thereby reducing system complexity while improving measurement accuracy.
Solution Approach 2:
The patent replaces direct mechanical measurement of pullwire tension with an electrical/sensor-based measurement system. Instead of using complex mechanical force measurement devices, the system uses torque sensors and computational models to calculate tension based on torque measurements and known geometric parameters, simplifying the overall system while improving precision.
2Ease of operation
If kinematic modeling is used to predict catheter motion, then ease of operation is improved, but measurement precision of actual motion deteriorates due to unmodeled constraints
Solution Approach 1:
The system incorporates feedback mechanisms where torque sensors provide real-time measurements of actual torque applied to the pullwires. This feedback is used to adjust and refine the kinematic model predictions, allowing the system to compensate for unmodeled constraints and anatomical variations. The feedback loop continuously improves the accuracy of catheter position prediction while maintaining ease of operation through automated control adjustments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the precision and control of catheter movement by accurately measuring and managing pullwire tension, improving the accuracy of catheter positioning and reducing the risk of catheter failure during robotic surgical procedures.
Implementation Method 1
The control system is configured to actuate the at least one output motor in response to the information to drive an output shaft in communication with the elongate member, and the instrument driver is configured to determine an output shaft torque imparted by the output shaft to the elongate member.
Data Source
AI summary
This disclosure covers various concepts to use for obtaining measurement of tension in catheter pullwires to improve controllability of a robotic surgical system.