Pulley-Based Rotation Position Detection for Surgical Tool Holders
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Solution Overview
Problem
Existing rotation position detection systems for surgical assistance robots are complicated and bulky when detecting rotation angles exceeding 360 degrees, leading to issues like wire harness twisting and increased size and weight.
Innovation Solution
A rotation position detection unit utilizing a motor, drive-side and driven-side pulleys, a transmission belt, and a rotary encoder, where the drive-side pulley diameter is smaller than the driven-side pulley, allowing calculation of the insertion member's rotation position based on the pulley ratio, enabling detection of 360 degrees or more in a compact configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional rotation position detection system is used to detect rotation angles exceeding 360 degrees, then the detection capability is improved, but the device complexity and size increase
Solution Approach 1:
The patent introduces a pulley transmission mechanism as an intermediary between the rotary encoder and the insertion member. The pulleys convert the rotation angle of the insertion member into a different rotation angle for the encoder, enabling detection of rotations exceeding 360 degrees while keeping the encoder itself simple and compact.
Solution Approach 2:
The patent changes the rotational parameter relationship between the insertion member and the encoder through the pulley ratio. By using pulleys with different diameters, the rotation angle is transformed, allowing the encoder to detect positions beyond its native 360-degree range without requiring a complex multi-encoder system.
2Measurement precision
If a conventional rotation position detection system is used to detect rotation angles exceeding 360 degrees, then the detection capability is improved, but the device size and weight increase
Solution Approach 1:
The pulley transmission mechanism acts as a compact intermediary that enables extended rotation detection without requiring multiple encoders or complex mechanical structures. This keeps the overall detection system lightweight while achieving the desired detection capability.
Solution Approach 2:
The patent uses a single rotary encoder to effectively 'copy' or represent the rotation position of the insertion member through the pulley ratio relationship. This eliminates the need for multiple encoders or redundant detection components, reducing weight while maintaining detection accuracy.
3Measurement precision
If wire harnesses are used in conventional detection systems for 360 degrees or more rotation, then the detection capability is improved, but wire harness twisting occurs
Solution Approach 1:
The pulley transmission mechanism serves as an intermediary that reduces the rotation angle transmitted to the encoder and its associated wire harnesses. By using the pulley ratio to decrease the encoder's rotation angle relative to the insertion member's rotation, the wire harnesses experience less twisting even when the insertion member rotates 360 degrees or more.
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 provides a simple and compact mechanism for detecting the rotation position of an insertion member, reducing size and weight while maintaining reliable detection accuracy without the need for complex multi-encoders or stopper mechanisms.
Implementation Method 1
a transmission belt that transmits a rotational drive of the drive-side pulley to the driven-side pulley
Data Source
AI summary
A rotation position detector includes a motor having a drive shaft extending along a first axis, a drive-side pulley that is connected to the drive shaft, a holder that holds a treatment tool to be inserted into a patient during surgery, the holder rotating in association with the drive-side pulley, a driven-side pulley that rotates around the first axis, a diameter of the drive-side pulley being smaller than a diameter of the driven-side pulley, a transmission belt that transmits a rotational drive of the drive-side pulley to the driven-side pulley, a rotary encoder that is provided on the first axis and detects a rotation angle of the driven-side pulley, and a controller that calculates a rotation position of the holder based on the rotation angle and based a pulley ratio of the drive-side pulley to the driven-side pulley, and controls the motor based on the rotation position.