Force Sensor Temperature Compensation via Proximal Extraction
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Solution Overview
Problem
Current surgical robot systems face challenges in providing accurate feedback of forces and torques to surgeons during robotic surgery, particularly due to the placement of force sensors distal to the wrist joints, which requires routing of wires or optic fibers through flexible joints and is sensitive to temperature variations, affecting measurement accuracy.
Innovation Solution
A force sensor apparatus with radial ribs and strain gauges positioned proximal to the wrist joint, using high thermal diffusivity materials and negative thermo-optic coefficient optical fibers, which provides accurate force signals and eliminates the need for delicate wires or optic fibers to pass through the wrist joint, while being thermally stable and adaptable to various surgical instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensors are placed distal to the wrist joints, then force sensing capability is improved, but device complexity and routing difficulty increase due to wires or optic fibers needing to pass through flexible joints
Solution Approach 1:
The force sensing capability is extracted from the distal end effector and relocated to the proximal instrument shaft. This eliminates the need to route wires or optic fibers through the flexible wrist joint, as the sensors are now positioned where routing is mechanically simpler and does not interfere with joint flexibility.
Solution Approach 2:
The instrument shaft acts as an intermediary mechanical element that transmits force information from the distal end effector to the proximal sensor location. By using the shaft as a mechanical mediator, force sensing is achieved without requiring delicate signal carriers to pass through the flexible joint.
2Measurement precision
If force sensors are placed distal to the wrist joints, then force sensing capability is improved, but temperature sensitivity increases affecting measurement accuracy
Solution Approach 1:
The force sensors are extracted from the distal location near the wrist joint and relocated to the proximal instrument shaft. This physical relocation removes the sensors from the thermally sensitive environment near the flexible joint, eliminating temperature-induced measurement errors while preserving force sensing capability.
3Measurement precision
If wires or optic fibers are routed through the wrist joint, then force sensing is enabled, but reliability decreases due to delicate components in flexible joints
Solution Approach 1:
The delicate wiring or optic fiber routing is extracted from the wrist joint environment and relocated to the proximal instrument shaft. This eliminates the reliability issues associated with having delicate signal carriers pass through flexible joints subject to repeated bending and mechanical stress.
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 enhances force and torque feedback to surgeons, improves user awareness and control, and maintains accuracy under asymmetric thermal loads, reducing the complexity of routing sensitive components through the wrist joint and addressing temperature sensitivity issues.
Implementation Method 1
a strain gauge or gauges positioned over each of the plurality of radial ribs
Implementation Method 2
using high thermal diffusivity materials
Implementation Method 3
negative thermo-optic coefficient optical fibers
Data Source
AI summary
A force sensor apparatus is provided including a tube portion having a plurality of radial ribs and at least one fiber optic strain gauge positioned over each rib of the plurality of radial ribs. A proximal end of the tube portion is operably couplable to a shaft of a surgical instrument that is operably couplable to a manipulator arm of a robotic surgical system, and a distal end of the tube portion is proximally couplable to a wrist joint coupled to an end effector. A thermal shunt shell is over an outer surface of the tube portion.