Interlocking Collet Retention for Bidirectional Surgical Tool Locking

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional collets used in robotic surgical systems often fail to securely retain surgical tools in both directions along the axis of rotation, leading to movement issues and bending moments when lateral loads are applied, causing tool slippage and inaccurate cutting.

Innovation Solution

An interlocking collet system with first and second locking members and a bias member is designed to exert opposing axial forces on the surgical tool, providing symmetric retention and resisting bending moments through distributed load, allowing secure retention and movement in either direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single locking mechanism is used to retain the tool, then the structure is simple, but the tool cannot be securely retained in both directions along the axis

Engineering Contradiction:
Improvelocking mechanism structureVSAvoidtool retention in both directions
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The locking mechanism is segmented into two separate locking members (first locking member and second locking member), each responsible for retaining the tool in one direction along the axis. This segmentation allows independent optimization of each locking member for its specific directional retention function, achieving reliable bidirectional retention without excessive complexity.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If a single locking mechanism retains the tool in one direction, then the structure is simple, but bending moments cause tool slippage when lateral loads are applied

Engineering Contradiction:
Improvelocking mechanism structureVSAvoidresistance to bending moments and lateral loads
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The two locking members are positioned to act as counterbalancing elements that collectively resist bending moments. When lateral loads are applied, the locking members distribute the counteracting forces along the tool axis, neutralizing the bending moment effect and preventing tool slippage, thereby enhancing strength without complicating the overall structure.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

3Device complexity

If a single locking mechanism is used, then the device is simple, but the tool may move along the axis altering the cutting location

Engineering Contradiction:
Improveretention mechanismVSAvoidcutting location accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The retention mechanism is divided into two independent locking members that respectively constrain the tool in opposite axial directions. This segmentation ensures that the tool cannot move along the axis in either direction, maintaining precise cutting location accuracy without requiring an overly complex retention system.

Inventive Principle:
Principle #1Segmentation

4Reliability

If opposing axial forces are exerted on the tool, then retention stability is improved, but the device complexity increases

Engineering Contradiction:
Improvetool retention stabilityVSAvoidlocking members and bias member configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The first and second locking members are integrated within a single collet housing structure, sharing common bias members and spatial arrangement. This merging approach allows opposing axial forces to be exerted on the tool while maintaining a compact, unified device design, minimizing the increase in overall complexity despite the enhanced retention stability.

Inventive Principle:
Principle #5Merging (Combining)

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 interlocking collet system ensures stable and precise tool retention, reducing deflection and slippage, and facilitating efficient and uniform material removal during surgical procedures.

Implementation Method 1

at least one bias member disposed within the bore of the housing... arranged to position the first locking member along the axis in a first position in which the first locking member is configured to contact the first attachment surface

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 2

The at least one bias member is arranged to position the second locking member along the axis in a second position in which the second locking member is configured to contact the second attachment surface

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 3

The first and second locking members in the first and second positions, respectively, are configured to exert opposing axial forces on the attachment

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Data Source

PatentEP4216859B1Interlocking collet system for a surgical device
Publication Date: 2024.12.11 MAKO SURGICAL CORP
  • EP4216859B1 patent drawingFigure 1
  • EP4216859B1 patent drawingFigure 2
  • EP4216859B1 patent drawingFigure 3

AI summary

An interlocking collet system includes an attachment (106) comprising first and second attachment surfaces (108, 110) spaced from one another and a collet. The collet comprises a housing configured to extend along an axis. The housing defines a bore for selectively disposing and retaining the attachment therein in an installed position. First and second locking members (122, 124) are disposed within the bore and are moveable. At least one bias member (126) is disposed within the bore and is arranged to position the first locking member in a first position in which the first locking member is configured to contact the first attachment surface. The at least one bias member is arranged to position the second locking member in a second position in which the second locking member is configured to contact the second attachment surface. The first and second locking members are configured to exert opposing axial forces on the attachment.