End Effector Arm Gravity Compensation for Precise Surgical Guidance
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Solution Overview
Problem
Conventional surgical guidance systems for robotic surgery, such as those used in total knee arthroplasty, face challenges in maintaining precision and reducing surgeon strain due to the weight of end effector components, especially when resection planes are inclined or vertical, leading to inaccurate cuts and physical stress on the surgeon.
Innovation Solution
An end effector arm with a spring mechanism that imparts a variable rotational force based on the angle of rotation, compensating for gravitational forces across a range of angles, ensuring precise tool guidance and reducing surgeon effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Aluminum material is used for structural parts to reduce manufacturing cost and improve measurement precision with encoders, then manufacturing cost and measurement precision are improved, but the weight of structural parts increases causing strain on surgeon's hand
Solution Approach 1:
A spring mechanism is integrated into the end effector arm to provide an upward counterbalancing force that offsets the gravitational force acting on the arm. The spring is positioned and tensioned to generate a force equal to or slightly greater than the weight of the arm, creating a counterweight effect that eliminates the need for the surgeon to support the arm's weight during operation.
2Adaptability or versatility
If the resection plane is inclined or vertical, then surgical versatility is improved, but the weight of links is partially or totally supported by surgeon's hand causing strain
Solution Approach 1:
The spring mechanism provides continuous gravitational compensation regardless of the end effector arm's orientation. When the resection plane is inclined or vertical, the spring's upward force counteracts the component of gravitational force acting on the arm, preventing the surgeon from having to support the full weight and reducing hand strain during versatile positioning.
Solution Approach 2:
The spring mechanism dynamically adjusts to the end effector arm's position and orientation, providing variable gravitational compensation. As the arm moves through different angles and positions during surgery, the spring automatically adjusts its mechanical advantage and force application to maintain neutral buoyancy, enabling smooth operation across all resection plane configurations.
3Manufacturing precision
If passive structure is designed with highest possible transverse stiffness, then resection accuracy is improved, but the weight of structural parts increases
Solution Approach 1:
The spring mechanism compensates for the weight of the stiff structural components, allowing the use of heavy, high-stiffness materials without penalizing the surgeon. The counterbalancing force neutralizes the gravitational effect of the dense materials, enabling the structure to be both stiff for accuracy and heavy for performance without creating operational strain.
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 precision in surgical cuts and minimizes surgeon fatigue by dynamically balancing the weight of the end effector arm, maintaining accurate tool guidance regardless of the resection plane orientation.
Implementation Method 1
a spring mechanism configured to impart a variable rotational force on the mechanical linkage based on an angle of rotation of the mechanical linkage with respect to the base
Data Source
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AI summary
An end effector arm for use with a surgical navigation system includes a base configured to attach to an end effector coupler of a surgical robot arm and a mechanical linkage. The mechanical linkage includes a first end rotatably coupled to the base and a second end opposite the first end, the second end configured to be removably coupled to a handheld surgical tool. The end effector arm further includes a spring mechanism configured to impart a variable rotational force on the mechanical linkage based on an angle of rotation of the mechanical linkage with respect to the base.