Optical Force Torque Sensor Assembly for Robotic Surgery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Force/torque sensor assemblies in robotic surgical systems face challenges with thermal drift and limited resolution, affecting the accuracy of force and torque measurements, which can lead to inaccurate placement of surgical instruments during procedures.
Innovation Solution
An optically-based force/torque sensor assembly using a light sensitive transducer with a plurality of pixels, where light beams are directed onto the transducer to sense displacement and determine forces and torques, providing multiple resolution capabilities and avoiding thermal drift issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are used to measure forces and torques, then the measurement capability is provided, but thermal drift occurs causing inaccurate measurements
Solution Approach 1:
The patent replaces the mechanical strain gauge system with an optical measurement system. A light source emits light that reflects off a mirror attached to the sensor member onto a light-sensitive transducer. When forces or torques are applied, the sensor member displaces, causing the mirror to rotate and the light spot to move across the transducer, providing thermal-drift-free measurements.
2Adaptability or versatility
If a single resolution measurement system is used, then the device complexity is reduced, but the capability to measure at multiple resolutions is lost
Solution Approach 1:
The patent uses a light-sensitive transducer with multiple rows of photodetectors arranged in different dimensions. By detecting the position of the light spot across multiple rows and combining signals differentially, the system achieves multiple resolution levels (first resolution using all rows, second resolution using subsets of rows) without adding separate measurement systems.
3Measurement precision
If strain gauges are used, then force and torque measurement is enabled, but thermal expansion and contraction of parts causes measurement errors
Solution Approach 1:
The patent eliminates the mechanical strain gauge system that is susceptible to thermal effects by implementing an optical lever system. The light-based measurement is immune to thermal expansion and contraction, as the measurement depends on light position rather than mechanical dimension changes.
4Measurement precision
If multiple light beams are used to improve measurement resolution, then the sensitivity is enhanced, but the device complexity increases
Solution Approach 1:
The patent combines multiple light beams (first and second light beams) that reflect from the same mirror onto a single light-sensitive transducer. The transducer integrates the detection of multiple beams across its photodetector array, enabling differential measurements and multiple resolution levels without requiring separate detection systems for each beam.
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
The sensor assembly effectively measures forces and torques at different resolutions, enhancing the accuracy and precision of surgical instrument placement by eliminating thermal drift and offering improved sensitivity stages, thus improving surgical precision.
Implementation Method 1
A light source provides light to be directed in a plurality of light beams onto the light sensitive transducer so that the light beams strike different pixels of the light sensitive transducer to sense displacement of a sensor member relative to a base plate
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A sensor assembly comprises a base plate, a sensor member displaceable relative to said base plate, a light sensitive transducer having a plurality of pixels, and a light source configured to provide light directed in a plurality of light beams onto said light sensitive transducer so that the light beams strike different pixels of said light sensitive transducer to sense displacement of said sensor member relative to said base plate.