Surgical Robot Cannula Force Sensing via Axial Deformation
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Solution Overview
Problem
Conventional surgical robot systems face issues with structural and computational complexity, and low accuracy in measuring contact forces at the terminal end of surgical instruments, which affects the surgeon's perception and the outcome of the procedure.
Innovation Solution
A surgical robot system comprising a slave unit with a robotic arm, a cannula, and a sensing element that determines radial forces on the surgical instrument's terminal end based on axial deformation, using a principle of torque balance and point-contact mechanisms, thereby simplifying force transmission and enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional force transducers and measurement components are employed to measure forces on surgical instruments, then force feedback capability is achieved, but structural complexity and device mass increase significantly
Solution Approach 1:
The patent extracts the force measurement function from complex multi-sensor systems and concentrates it into a single force transducer integrated into the trocar. By removing unnecessary measurement components and focusing on one critical measurement point (the force at the surgical site), the system achieves force feedback capability while minimizing structural complexity and mass increase.
Solution Approach 2:
The trocar is designed to serve multiple functions: it acts as both the delivery mechanism for the surgical instrument and the force measurement device. The force transducer is integrated into the trocar structure itself, allowing the same component to perform both mechanical delivery and force sensing functions, thereby reducing the need for separate dedicated measurement components.
2Measurement precision
If multiple force transducers are disposed at different locations to measure forces, then measurement accuracy is improved, but computational complexity and algorithm requirements increase
Solution Approach 1:
The patent extracts the force measurement to a single critical location - the force transducer at the trocar-surgical site interface. By focusing measurement on the most important force (the direct interaction force between instrument and tissue) rather than attempting to measure multiple forces throughout the system, the patent achieves adequate measurement precision while avoiding complex computational algorithms for force reconstruction.
3Reliability
If indirect measurement methods are used with additional components, then force feedback is achieved, but the surgical instrument's mass and structural complexity increase
Solution Approach 1:
The patent merges the force transducer directly into the trocar structure, combining the force sensing function with the existing delivery mechanism. This integration eliminates the need for separate additional components that would increase mass, as the force transducer becomes part of the trocar assembly that is already required for instrument delivery.
Solution Approach 2:
The trocar serves dual purposes: delivering the surgical instrument and measuring forces. By making the force measurement system multi-functional rather than adding a dedicated separate measurement device, the patent avoids the mass penalty that would result from duplicating components solely for measurement purposes.
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 solution provides a more accurate and simpler method for measuring radial forces on surgical instruments, reducing structural complexity and facilitating the use of existing instruments, while improving the surgeon's feedback and procedural outcomes.
Implementation Method 1
the sensing element is disposed on the cannula and configured to sense an axial deformation of the cannula
Data Source
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AI summary
A surgical robot system includes a slave unit and a computing unit (10). The slave unit includes a robotic arm (2), a surgical instrument (3), a cannula (9) and a sensing element (903). The robotic arm (2) is configured to drive the surgical instrument (3) to rotate about a remote center of motion (RCM). The cannula (9) is detachably coupled to a terminal of the robotic arm (2) and defines an axis passing through the RCM. The surgical instrument (3) is detachably connected with the terminal of the robotic arm (2) and extends distally through the cannula (9), and the sensing element (903) is disposed on the cannula (9) and configured to sense an axial deformation of the cannula (9). The computing unit (10) is configured to determine a radial force acting on the terminal of the surgical instrument (3), from a force on the cannula (9) sensed by the sensing element (903), according to the principle of torque balance. This surgical robot system has force feedback capabilities and obtains the radial force acting on the terminal of the surgical instrument (3) directly from a measurement with higher accuracy and not requiring any additional component, providing for reduced structural complexity of the surgical instrument (3).