Torsion Cable Actuation for Robotic Surgical Tools
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Solution Overview
Problem
Current robotic surgical systems face limitations in actuating end effectors with precision and ease, particularly in minimally invasive procedures, due to the complexity of mechanical mechanisms and the need for intuitive hand movements that maintain natural eye-hand axis alignment.
Innovation Solution
The development of a robotic surgical tool incorporating a drive housing with a lead screw, a carriage, and a torsion cable system that allows for precise actuation of end effectors through a rotating drive input, enabling functions such as opening/closing jaws, articulating the end effector, and advancing/retracting a knife, with a tensioning system to maintain cable tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional mechanical mechanisms are used to actuate end effectors, then the structural strength and reliability are maintained, but the device complexity increases and ease of operation decreases
Solution Approach 1:
The patent replaces traditional complex mechanical actuation mechanisms with a tendon-based cable system. The cable runs through a pulley system and connects the actuator at the proximal end to the end effector at the distal end, allowing actuation through cable tension changes rather than complex mechanical linkages. This substitution reduces mechanical complexity while maintaining actuation functionality.
Solution Approach 2:
The patent divides the actuation system into separate functional components: the actuator mechanism at the proximal end, the cable transmission system, the pulley system, and the end effector at the distal end. This segmentation allows each component to be optimized independently and simplifies the overall system architecture by distributing functionality across multiple discrete elements rather than using a monolithic mechanical mechanism.
2Ease of operation
If robotic systems maintain natural eye-hand axis alignment, then ease of operation improves, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent designs the instrument shaft to serve multiple functions: it acts as both the structural support element and the transmission path for the actuation cable. The shaft provides mechanical support for the end effector while simultaneously serving as the conduit through which the cable runs to transmit actuation forces. This multi-functionality reduces the need for separate control mechanisms while maintaining intuitive operation.
Solution Approach 2:
Instead of using complex mechanical linkages to transmit motion from the actuator to the end effector, the patent inverts the approach by using a flexible cable system that transmits tension forces through the shaft. The cable is anchored at both ends and tensionsed to move the end effector, reversing the traditional approach of using rigid mechanical connections.
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 enhances the precision and ease of actuating end effectors, improving the performance of minimally invasive surgical procedures by allowing for more intuitive and controlled movements, thereby improving surgical efficiency and reducing operator fatigue.
Implementation Method 1
a torsion cable extending between the drive gear and a drive input arranged at the first end, wherein rotating the drive input rotates the torsion cable and thereby transmits a torsional load along the torsion cable to the drive gear to actuate the activating mechanism
Implementation Method 2
a lead screw extending between the first and second ends, a carriage movably mounted to the lead screw at a carriage nut secured to the carriage
Data Source
AI summary
A robotic surgical tool includes a drive housing having a first end, a second end, and a lead screw extending between the first and second ends, a carriage movably mounted to the lead screw at a carriage nut secured to the carriage, and an activating mechanism including a drive gear rotatably mounted to the carriage and rotatable to actuate the activating mechanism. A torsion cable extends between the drive gear and a drive input arranged at the first end, wherein rotating the drive input rotates the torsion cable and thereby transmits a torsional load along the torsion cable to the drive gear to actuate the activating mechanism.