Articulated Arm CMM Joint Housing for Encoder Alignment

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Solution Overview

Problem

Conventional coordinate measuring machines (CMMs) face challenges in achieving high accuracy, reliability, durability, ease of use, and low cost, particularly in the design of articulated arms which require complex joint assemblies and separate housings for encoders, leading to increased parts, assembly time, and potential misalignment issues.

Innovation Solution

The articulated arm CMM system incorporates a dual-axis housing for combined hinge and swiveling joints, reducing parts and misalignment, along with a counterbalance system that shortens the first axis of rotation and integrates electronics in a removable handle for modular functionality and improved sealing, while using non-contact scanning and detection components for enhanced data acquisition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If separate housings are used for encoders and joint assemblies, then each joint can be independently assembled, but the number of parts increases and assembly time increases

Engineering Contradiction:
ImproveIndependent assembly capabilityVSAvoidNumber of parts
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The encoder housing and joint assembly housing are merged into a single integrated housing structure. The encoder is mounted directly within the joint assembly housing, eliminating the need for separate encoder housings and reducing the total number of parts while maintaining independent assembly capability through modular joint cartridge design.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of manufacture

If separate housings are used for encoders and joint assemblies, then manufacturing is simplified, but assembly time increases

Engineering Contradiction:
ImproveManufacturing simplicityVSAvoidAssembly time
Core Design Contradiction:
Ease of manufactureVSLoss of time

Solution Approach 1:

The joint assembly is segmented into modular cartridges that can be pre-assembled and tested independently, then quickly installed into the articulated arm. This modular cartridge approach maintains manufacturing simplicity while significantly reducing final assembly time through standardized interfaces and quick-connect mechanisms.

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If complex joint assemblies with separate housings are used, then each component can be optimized independently, but misalignment issues increase

Engineering Contradiction:
ImproveComponent optimizationVSAvoidAlignment accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

By integrating the encoder mounting directly into the joint assembly housing with precision-machined reference surfaces, the patent eliminates misalignment issues between separate housings. The encoder shaft is directly coupled to the joint axis through precision bearings within the same housing, ensuring accurate alignment while still allowing independent optimization of encoder and joint components during the design phase.

Inventive Principle:
Principle #5Merging (Combining)

4Strength

If traditional articulated arm design is used, then structural integrity is maintained, but weight increases

Engineering Contradiction:
ImproveStructural integrityVSAvoidArticulated arm weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The articulated arm members are constructed using composite materials such as carbon fiber reinforced polymers or aluminum alloys with optimized cross-sections. These composite structures maintain the required structural integrity and stiffness for accurate measurement while significantly reducing the weight compared to traditional solid metal construction, improving the arm's maneuverability and reducing counterbalance requirements.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3382328B1Articulated arm CMM system
Publication Date: 2023.09.06 HEXAGON TECH CENT GMBH
  • EP3382328B1 patent drawingFigure 1
  • EP3382328B1 patent drawingFigure 1A
  • EP3382328B1 patent drawingFigure 2

AI summary

The invention relates to an articulated arm CMM comprises an articulated arm and a handle. The articulated arm includes a plurality of articulated arm members, a coordinate acquisition member at a distal end, and a base at a proximal end. The handle includes electronics and be removable connected to the coordinate acquisition member.