Bell Crank Transmission for Roll-to-Linear Surgical Actuation
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Solution Overview
Problem
Existing technologies face challenges in efficiently transmitting rotary actuating forces to push-pull drive elements within the elongate tubes of surgical instruments used in teleoperated minimally invasive surgeries, while maintaining a compact design to minimize the size of the incision.
Innovation Solution
A force transmission mechanism that includes a chassis supporting a rotatable arm with a slot, a rotatable lever with a protrusion engaging the slot, and a sliding drive element extending through an elongate tube. This mechanism allows for the transmission of rotary forces to the drive element, enabling it to rotate in unison with the elongate tube while translating along its length to actuate the surgical end effector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rotary actuators are used to provide controlled actuation forces, then actuation precision is improved, but device complexity increases due to the need for compact proximal control mechanism
Solution Approach 1:
The patent replaces complex mechanical proximal control mechanisms with a distal control architecture. A rotary actuator at the distal end directly controls the end effector, eliminating the need for complex mechanical transmissions (gears, linkages, cables) in the proximal control mechanism. This substitution maintains actuation precision while significantly reducing device complexity and the number of moving parts in the extension tube.
2Length of moving object
If the extension tube diameter is minimized, then incision size is reduced, but force transmission efficiency deteriorates
Solution Approach 1:
The patent extracts the force transmission function from the extension tube wall and relocates it to a separate, dedicated drive shaft positioned along the central axis of the tube. This allows the extension tube to be minimized in diameter for small incisions, while the drive shaft maintains sufficient structural integrity and surface area for efficient force transmission from the distal actuator to the end effector.
Solution Approach 2:
The patent introduces a drive shaft as an intermediary component between the distal actuator and the end effector. This drive shaft serves as a dedicated force transmission element that compensates for the reduced force transmission capacity resulting from the minimized extension tube diameter, thereby maintaining force transmission efficiency despite the smaller overall device size.
3Adaptability or versatility
If multiple drive elements are used to control push-pull motions and rotation, then control versatility is improved, but device complexity increases due to crowding in the surgical field
Solution Approach 1:
The patent implements a universal control architecture where a single distal rotary actuator performs multiple functions. By positioning the actuator at the distal end, it can independently control both the push-pull motion (via a drive shaft connected to the end effector) and the rotation (via direct connection or a separate drive shaft) of the end effector. This multi-functionality eliminates the need for separate proximal actuators and their associated drive elements, reducing device complexity and crowding in the surgical field while maintaining full control versatility.
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 mechanism effectively transmits rotary actuating forces to the push-pull drive element, allowing for precise control of the surgical end effector while maintaining a compact design that minimizes the diameter of the extension tube, thus reducing the size of the incision required.
Implementation Method 1
The bell crank may be a rocker that converts the rotary motion of the actuator into the linear motion of the drive element
Data Source
AI summary
A force transmission mechanism includes a chassis that supports a rotatable arm, which includes a slot. A rotatable lever is supported by the chassis. A protrusion at an end of the lever engages the slot. A sliding drive element is supported by the chassis. A proximal termination of the drive element engages a second end of the lever. The chassis may support an elongate tube with an end effector fixed to the tube. The drive element may extend through the elongate tube. The elongate tube may rotate relative to the chassis. The drive element may rotate in unison with the elongate tube with the proximal termination rotating relative to the fork. The drive element may be a tube that provides a fluid passage to the end effector. The lever may be a bell crank with arms at a right angle.