Pulley-Based Rotation Position Detection for Medical Robot Insertion Members
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Solution Overview
Problem
Existing medical robots face challenges in detecting the rotation position of insertion members that rotate beyond 360 degrees, leading to complex configurations, increased size, and weight, as well as issues with wire harness twisting and disconnection.
Innovation Solution
A rotation position detection unit comprising a motor, drive-side and driven-side pulleys, a transmission belt, and a rotary encoder, where the pulley ratio is set to allow detection of rotation positions exceeding 360 degrees in a simple and compact configuration, using an intermediate pulley and a control unit to calculate the rotation position based on the rotation angle of the driven-side pulley.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multi-encoder or single-turn encoder combined with zero-point limit switch is used to detect rotation position exceeding 360 degrees, then the rotation position detection capability is improved, but the device complexity and size are increased
Solution Approach 1:
The patent replaces complex mechanical detection systems (multi-encoder or single-turn encoder with zero-point limit switch) with a simpler optical encoder system combined with pulley ratio mechanics. The rotary encoder detects the rotation angle of the driven-side pulley, and the control unit calculates the insertion member's rotation position based on the pulley ratio, eliminating the need for complex multi-encoder configurations or zero-point limit switches.
Solution Approach 2:
The patent introduces an intermediate pulley system as a mechanical intermediary between the motor and the insertion member. The drive-side pulley (smaller diameter) and driven-side pulley (larger diameter) create a pulley ratio that allows the rotary encoder to detect a reduced rotation angle range while the insertion member achieves the required larger rotation range, effectively mediating between the detection capability and the operational requirement.
2Measurement precision
If a multi-encoder or single-turn encoder combined with zero-point limit switch is used to detect rotation position exceeding 360 degrees, then the rotation position detection capability is improved, but the device size is increased
Solution Approach 1:
The patent replaces bulky mechanical detection systems with a compact rotary encoder and pulley ratio mechanism. The rotary encoder mounted on the driven-side pulley axis requires minimal space, and the pulley ratio system allows the encoder to detect a smaller rotation angle while the insertion member rotates through the required larger angle, significantly reducing the overall detection device size.
Solution Approach 2:
The patent changes the detection parameter from directly measuring the full rotation angle of the insertion member to measuring a scaled-down rotation angle of the driven-side pulley. By utilizing the pulley ratio (where the driven-side pulley has a larger diameter and thus rotates through a smaller angle for the same linear belt displacement), the system achieves accurate detection of large rotation ranges with a compact encoder that only needs to measure a smaller angle range.
3Adaptability or versatility
If the rotation exceeds 360 degrees, then the rotation function capability is improved, but the wire harness twisting and disconnection problems occur
Solution Approach 1:
The patent introduces the pulley system as a mechanical intermediary that decouples the rotation motion of the insertion member from the wire harness. The wire harness connects to the drive-side pulley (or fixed frame), while the insertion member rotates relative to it through the pulley ratio mechanism. This intermediary arrangement allows the insertion member to rotate more than 360 degrees without causing the wire harness to twist or disconnect, as the wire harness does not need to follow the full rotation path.
4Reliability
If a stopper mechanism for restricting the rotation amount of the wire harness is provided, then the wire harness protection is improved, but the device size and weight are increased
Solution Approach 1:
The patent replaces the need for stopper mechanisms with a pulley ratio system that inherently prevents wire harness over-rotation. By mounting the rotary encoder on the driven-side pulley and using the pulley ratio relationship, the system allows the insertion member to rotate freely through large angles while the encoder and wire harness remain within safe rotation limits, eliminating the need for additional stopper mechanisms and their associated weight.
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 the detection of rotation positions of insertion members that rotate 360 degrees or more in a medical robot with a compact and simplified design, reducing size and weight while preventing wire harness issues.
Implementation Method 1
a transmission belt that transmits rotational drive of the drive-side pulley to the driven-side pulley
Data Source
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AI summary
An object is to provide a rotation position detection unit capable of detecting the rotation position of an insertion member that is to be inserted into the patient's body and can rotate 360 degrees or more in a simple and compact configuration in a medical robot that holds the insertion member in a rotatable manner. The rotation position detection unit comprises: a motor; a drive-side pulley that is connected to the motor and rotationally driven by the motor around a drive shaft of the motor; a driven-side pulley that rotates around a first axis of rotation; a transmission belt that transmits rotational drive of the drive-side pulley to the driven-side pulley; a rotary encoder that is connected to the first axis of rotation and detects a rotation angle of the driven-side pulley; and a control unit that controls drive of the motor and to which a detection result by the rotary encoder is input. The insertion member rotates in association with rotation of the drive-side pulley. The diameter of the drive-side pulley is smaller than the diameter of the driven-side pulley. The control unit calculates the rotation position of the insertion member based on the rotation angle of the driven-side pulley and a pulley ratio obtained by dividing the diameter of the drive-side pulley by the diameter of the driven-side pulley.