Sensor-Aligned Cable Guide for Surgical Instrument Force Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In teleoperated surgical systems, extraneous forces from twisting control cables within the shaft introduce errors in clinical force measurements due to the interaction between the end effector and patient tissue, as the cables are not isolated from mechanical forces, leading to inaccurate force feedback.
Innovation Solution
A surgical instrument design with a force sensor aligned coaxially within the shaft, featuring proximal and distal anchors with cable guide holes that maintain control cables parallel to the shaft center axis, isolating clinical forces from extraneous mechanical forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If control cables extend within the shaft to actuate the end effector, then the instrument can be teleoperated with multiple degrees of motion, but extraneous forces from cable twisting introduce errors in clinical force measurements
Solution Approach 1:
The interior of the shaft is segmented into distinct functional zones: a force sensing zone where the force sensor is located, and a cable routing zone where cables are guided through aligned holes. This segmentation isolates the force measurement function from cable interference, allowing accurate force sensing while maintaining teleoperation capability through separate cable routing paths.
2Adaptability or versatility
If the shaft rolls around its longitudinal axis during surgery, then the instrument can adapt to different surgical positions, but the cables twist and generate extraneous forces that mask clinical force cues
Solution Approach 1:
Aligned cable guide holes serve as intermediary structures that mediate between the shaft's rotational movement and the cables. These holes constrain cables to move parallel to the shaft axis while allowing the shaft to roll freely, acting as a mechanical intermediary that decouples shaft rotation from cable twisting and eliminates harmful extraneous forces.
3Loss of information
If a force sensor is placed within the shaft to measure clinical forces, then force feedback can be provided to the surgeon, but the sensor readings are contaminated by extraneous forces from control cables
Solution Approach 1:
The cable routing function is extracted from the force sensing environment. Cables are routed through aligned guide holes that are spatially separated from the force sensor's measurement zone, and constrained to move parallel to the shaft axis. This extraction removes cable-related extraneous forces from the force sensor's measurement environment, enabling accurate clinical force feedback.
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
Accurate measurement and haptic feedback of clinical forces are achieved by ensuring control cables remain parallel to the force sensor beam, eliminating errors caused by twisting, thereby providing precise force feedback to the surgeon.
Implementation Method 1
The force sensor comprises a beam and one or more strain gauges on the beam
Data Source
AI summary
Control cables in a surgical instrument are kept parallel to the instrument's longitudinal axis to prevent transverse forces from the cables being sensed by a transverse force sensor in the instrument. A surgical instrument includes an elongated hollow shaft having a longitudinal center axis. Multiple cables extend within the shaft. A force sensor includes a beam disposed within the shaft and one or more strain gauges disposed on the beam. A proximal anchor is disposed within the shaft and in contact with a proximal end of the beam. A distal anchor is at the distal end of the shaft and in contact with a distal end of the beam. A cable guide is disposed within the shaft to constrain portions of the multiple cables disposed alongside the beam to movement parallel to the center axis, and so prevent force from the moving cables causing transverse force on the beam.