Minimally Invasive Surgical Instrument Force Sensor Placement
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Solution Overview
Problem
Existing minimally invasive surgical instruments face challenges in accurately measuring force exerted on working elements due to signal distortion from ambient temperature and position-dependent measurements, particularly when force sensors are routed along hinges.
Innovation Solution
The placement of force sensors on the frame near the opening between the first and second working element origins, combined with strain sensors and temperature compensation, allows for independent force measurement independent of tissue position and reduces signal distortion by avoiding transmission over rotating hinges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensors are routed along hinges to measure gripping force, then force measurement capability is provided, but measurement accuracy deteriorates due to signal distortion from temperature and hinge deflection
Solution Approach 1:
The force sensor is extracted from the hinge structure and relocated to the frame body, separating the measurement function from the moving hinge components. This eliminates signal distortion caused by hinge deflection and temperature variations, as the sensor remains in a stable position on the frame while still measuring the gripping force through the structural connection.
Solution Approach 2:
The frame serves as an intermediary structure that transmits the gripping force from the working elements to the force sensor. By positioning the sensor on the frame near the opening between working element origins, the frame mediates the force transmission while keeping the sensor isolated from direct hinge movement and temperature effects.
2Measurement precision
If force sensors are positioned on working elements to measure gripping force, then force feedback is provided, but measurement accuracy deteriorates due to position-dependent measurements
Solution Approach 1:
The force sensor is extracted from the working elements themselves and positioned on the frame structure. This separation allows the sensor to measure the resultant gripping force through the frame's structural transmission without being affected by the positional variations of the working elements or tissue location, eliminating position-dependent measurement errors.
Solution Approach 2:
The frame structure serves multiple functions: it provides structural support, transmits forces from the working elements to the sensor, and positions the sensor in an optimal location for measurement. This multi-functionality allows a single sensor position on the frame to capture gripping force information independent of working element positions.
3Ease of operation
If force sensors are placed on moving parts to enable real-time feedback, then operational control is improved, but reliability deteriorates due to vulnerable sensor signals over rotating hinges
Solution Approach 1:
The force sensor and its signal transmission path are extracted from the moving hinge components and relocated to the stationary frame. This eliminates the vulnerability of sensor signals to damage from rotating hinges, while the frame's structural connection ensures continuous real-time force feedback for operational control.
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 configuration enhances the accuracy and sensitivity of force measurement, providing a temperature-invariant and position-independent feedback for precise control of surgical instruments during minimally invasive procedures.
Implementation Method 1
for the force sensor one or more strain sensors are used. Strain sensors can be used to measure force because a force increment dF causes a strain dx
Implementation Method 2
strain can be used to measure temperature because temperature increment dT causes a material to extend: dx=a.dT
Data Source
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AI summary
The invention relates to an instrument, preferably for minimally invasive surgery,comprising a frame (27) having a proximal end and a distal end, a first working element (4) having a first origin located at the distal end and a second working element (5) having a second origin and being arranged at the distal end cooperating with the first working element, a force sensor for measuring a force exerted on at least one of the saidthe first and the second working elements, wherein the distal end of the frame comprises an opening (23) between the first origin and the second origin, the force sensor being arranged on the frame in a vicinity of the opening.