Spread-Bridge Force Sensor Layout for Redundant XY Measurement
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Solution Overview
Problem
Existing force sensors for surgical instruments face challenges in accurately measuring orthogonal forces while dealing with limited space and manufacturing constraints, leading to potential errors and increased costs due to the impracticality of adding additional full-bridges.
Innovation Solution
A beam with four Wheatstone half-bridges located on the surface, where each half-bridge is laterally spaced apart to measure orthogonal components of force, allowing for redundant measurements to detect sensor errors and reduce strain on conductor traces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional full-bridges are added to produce redundant force measurements for error detection, then sensor reliability is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent divides each full-bridge into two separate half-bridges, with each half-bridge containing only two strain gauges instead of four. This segmentation allows the same force measurement functionality to be achieved with fewer gauges per bridge, enabling redundant measurements without proportionally increasing complexity or cost.
Solution Approach 2:
The patent changes the configuration parameter from full-bridges (4 gauges each) to half-bridges (2 gauges each). This parameter change maintains the ability to measure orthogonal forces while reducing the total number of gauges needed for redundant measurements, thereby improving reliability without significantly increasing device complexity.
2Reliability
If additional full-bridges are added to produce redundant force measurements for error detection, then sensor reliability is improved, but manufacturing cost increases significantly
Solution Approach 1:
By segmenting full-bridges into half-bridges, the patent reduces the number of strain gauges required per measurement channel. This segmentation enables cost-effective redundant measurements since fewer expensive strain gauges are needed while still achieving the same reliability through multiple measurement channels.
Solution Approach 2:
The patent uses simpler half-bridge configurations that are less costly to manufacture than full-bridges. By employing multiple half-bridges instead of fewer full-bridges, the system achieves redundant measurements using cheaper components, thereby improving reliability without significantly increasing manufacturing cost.
3Reliability
If four full-bridges are formed on four sides of the beam, then redundant force measurements for error detection are achieved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent segments the bridge structure into half-bridges that can be more easily manufactured and positioned on the beam. This segmentation simplifies the manufacturing process while still enabling redundant measurements across multiple sides of the beam for error detection.
Solution Approach 2:
By changing from full-bridge to half-bridge configuration, the patent reduces manufacturing complexity. Half-bridges require fewer strain gauges and simpler wiring, making them easier to manufacture and install while maintaining the capability for redundant error detection measurements.
4Measurement precision
If half-bridges are laterally spaced apart instead of clustered, then strain on conductor traces is reduced and measurement accuracy is improved, but device area increases
Solution Approach 1:
The patent arranges half-bridges in a lateral spread configuration across the width of the beam rather than clustering them in one location. This dimensional arrangement distributes the strain load across different areas, reducing stress on individual conductor traces while maintaining measurement accuracy through the distributed gauge configuration.
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 solution provides accurate measurement of orthogonal forces with reduced manufacturing complexity and cost, enhancing sensor reliability and reducing strain on conductor traces, thereby improving surgical instrument performance.
Implementation Method 1
A force sensor includes a beam with four Wheatstone half-bridges ('half bridges') located on a beam surface
Implementation Method 2
electrical strain gauges formed on the force transducer... to measure strain imparted to the surgical instrument
Data Source
AI summary
A force sensor comprising a beam having a longitudinal center axis and a neutral axis that extends along a beam surface parallel to the center axis. A first half-bridge includes tension resistors. A second half-bridge includes tension resistors. A third half-bridge includes compression resistors. A fourth half-bridge includes compression resistors. The half-bridges are arranged on the beam surface such that redundant measurements of orthogonal components of a force imparted to the beam can be made using four different combinations of three of the half-bridges. The redundant measurements can be used to identify a malfunction of one or more of the resistors.