Surgical Instrument Gearbox With Spring-Controlled Closure Force
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Solution Overview
Problem
The design of surgical instruments for robotic surgical systems is constrained by the limited number and type of inputs provided by the robotic arm, necessitating innovative mechanisms to effectively utilize these inputs for desired functionalities.
Innovation Solution
A gearbox assembly incorporating a drive gear, hubs, a drive rod, and a compression spring, which translates rotational inputs into controlled movement of surgical instrument components, including a jaw mechanism, through a spring-compression mechanism that maintains closure force within a specified range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a robotic arm provides limited inputs to a surgical instrument, then the instrument design is constrained, but the system maintains simplicity and ease of operation
Solution Approach 1:
The surgical instrument is divided into modular components including a robotic arm module, a transmission module with gearbox assembly, and an end effector module. This segmentation allows each module to be optimized independently while maintaining overall system versatility without excessive complexity
Solution Approach 2:
The robotic arm is designed with universal inputs that can accommodate multiple types of surgical instruments and procedures. The standardized interface and multi-functional transmission mechanisms enable the same robotic arm to perform various surgical tasks with different instruments, enhancing adaptability without requiring complex specialized mechanisms for each function
2Force
If rotational input is directly translated to jaw movement, then the mechanism is simple, but closure force cannot be maintained within a specified range
Solution Approach 1:
The compression spring is pre-loaded to a specific compression amount before operation begins. This preliminary action ensures that the spring is positioned to exert the correct preliminary closure force on the jaw, allowing the transmission mechanism to maintain force within the specified range without requiring complex active control systems
Solution Approach 2:
The compression spring acts as an intermediary element between the rotational input and the jaw closure force. It mediates the force transmission by providing elastic compliance and maintaining consistent closure force within the specified range, absorbing variations and ensuring stable force application without direct mechanical coupling
3Force
If the compression spring is highly compressed to increase closure force, then the force range is adequate, but the spring may over-compress and damage components
Solution Approach 1:
The system incorporates feedback mechanisms through the spring's elastic properties and mechanical stops that prevent over-compression. As the jaw closes and tissue resistance increases, the spring compresses and provides natural feedback that modulates the closure force, preventing excessive compression forces that could damage components while maintaining adequate force within the operational range
Solution Approach 2:
The compression spring provides beforehand cushioning by being pre-loaded within safe compression limits. This preliminary cushioning ensures that the spring can absorb variations in tissue resistance and prevent sudden over-compression events that could damage components, while still providing adequate closure force for effective tissue grasping and cutting
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
Enables precise and controlled operation of surgical instruments, such as electrosurgical forceps, by translating rotational inputs into effective jaw movement and tissue grasping/cutting functions, while maintaining closure force within a desired range.
Implementation Method 1
a compression spring, which maintains closure force within a specified range during jaw movement
Implementation Method 2
a lead screw coupled to the round gear such that the rotational input to the round gear rotates the lead screw. The first hub is threadingly engaged about the lead screw such that rotation of the lead screw translates the first hub therealong
Data Source
AI summary
A gearbox assembly and surgical instrument including the same. The gearbox assembly includes a drive gear including a round gear and a lead screw such that a rotational input to the round gear rotates the lead screw. A first hub is threadingly engaged about the lead screw such that rotation of the lead screw translates the first hub. A second hub is spaced-apart from the first hub and engaged with a drive rod. A compression spring is disposed between the hubs. When a force acting against the drive rod is below a threshold, the rotational input translates the first hub, compression spring, second hub, and drive rod. When the force is equal to or above the threshold, the rotational input translates the first hub and compresses the compression spring against the second hub to maintain the second hub and drive rod in position.