Needle-Coupled Parallel Mechanism for Precision Control

Solution Overview

Problem

Serial mechanisms used in medical devices for controlling needle position and posture suffer from low precision due to cumulative errors and increased size and inertial mass, requiring a mechanism with a broad working area and high precision that can be controlled with a small force.

Innovation Solution

A needle-coupled parallel mechanism with a fixed frame, movable main shaft, and links featuring prismatic, 1-axis revolute, and spherical joints, allowing 6 degrees-of-freedom motion to control the needle's position and posture with reduced force and increased precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a serial mechanism is used to control needle position and posture, then the working area can be broad, but the precision becomes very low due to cumulative errors

Engineering Contradiction:

Improveneedle control precisionVSAvoidmechanism structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent inverts the traditional serial mechanism architecture by adopting a parallel mechanism where multiple independent links (first links and second links) connect the frame to the main shaft simultaneously. This inversion eliminates cumulative errors because each link independently supports the load, and errors do not propagate sequentially. The parallel structure with three first links and three second links creates redundant support paths that maintain precision while enabling broad working area through 6 degrees-of-freedom motion.

Inventive Principle:

Principle #13The other way round (Inversion)

2Measurement precision

If links are coupled in series to control needle position and posture, then the working area can be broad, but the size and inertial mass of the mechanism increase greatly

Engineering Contradiction:

Improveneedle control precisionVSAvoidmechanism inertial mass

Core Design Contradiction:

Measurement precisionVSWeight of moving object

Solution Approach 1:

The patent inverts the traditional serial mechanism architecture by adopting a parallel mechanism where multiple independent links (first links and second links) connect the frame to the main shaft simultaneously. This inversion eliminates cumulative errors because each link independently supports the load, and errors do not propagate sequentially. The parallel structure with three first links and three second links creates redundant support paths that maintain precision while enabling broad working area through 6 degrees-of-freedom motion.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If links are coupled in series to control needle position and posture, then the working area can be broad, but the force necessary to control the needle increases greatly

Engineering Contradiction:

Improveworking areaVSAvoidcontrol force

Core Design Contradiction:

Adaptability or versatilityVSForce

Solution Approach 1:

The patent inverts the traditional serial mechanism architecture by adopting a parallel mechanism where multiple independent links (first links and second links) connect the frame to the main shaft simultaneously. This inversion eliminates cumulative errors because each link independently supports the load, and errors do not propagate sequentially. The parallel structure with three first links and three second links creates redundant support paths that maintain precision while enabling broad working area through 6 degrees-of-freedom motion.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent merges multiple support paths by connecting three first links and three second links in parallel between the frame and the main shaft. This merging of redundant support paths distributes the control force across multiple independent links, reducing the force requirement on each individual link while maintaining overall system capability. The combined parallel structure provides synergistic support that enables broad working area with reduced control force.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS8535335B2Needle-coupled parallel mechanism

Publication Date: 2013.09.17 INDUSTRY UNIVERSITY COOPERATION FOUNDATION HANYANG UNIVERSITY

AI summary

A needle-coupled parallel mechanism is provided. The needle-coupled parallel mechanism is structurally improved so as to have a broad working area and a high precision. The needle-coupled parallel mechanism comprises a fixedly positioned frame, a main shaft, three first links, three second links, and a needle. The main shaft is arranged so as to be movable relative to the frame. One end of each of the first links is connected to the frame between both ends of the main shaft and the other end thereof is connected to one end of the main shaft. One end of each of the second links is connected to the frame between both ends of the main shaft and the other end thereof is connected to the other end of the main shaft. The needle is linearly movably coupled to the main shaft to perform a predetermined operation on a target object. Each of the first links and the second links has at least three joints selected from a prismatic joint, a 1-axis revolute joint, a 2-axis revolute joint and a spherical joint. The needle and the main shaft are moved with 6 degrees-of-freedom in conjunction with the operations of the first links and the second links.