Articulated CMM Counterweight Hinge for Gravity Compensation

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Solution Overview

Problem

Existing portable articulated arm coordinate measuring machines (AACMMs) face challenges with excessive workload due to supporting heavy weights, non-natural postures, and uncontrolled movements, which can lead to injury or damage, while prior art counterweight members either increase weight or negatively affect accuracy.

Innovation Solution

A counterweight member is integrated with the first hinge of the AACMM, comprising a force-providing element, a static element, and an internal support to counteract gravitational torque, minimizing deformation and improving measurement accuracy by providing a stable orientation and reducing operator workload.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a counterweight member is added to compensate gravity, then operator workload is reduced, but the weight of the instrument increases

Engineering Contradiction:
Improveoperator workloadVSAvoidweight of the instrument
Core Design Contradiction:
Ease of operationVSWeight of moving object

Solution Approach 1:

The patent applies the counterweight principle by integrating a counterweight member with the first hinge that generates a counterbalancing force to compensate for gravitational effects on the articulated elements. This reduces the operator workload by automatically balancing the heavy weights during measurement operations, eliminating the need for manual support of intermediate joints.

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

2Ease of operation

If prior art counterweight members are used, then gravity compensation is provided, but measurement accuracy is negatively influenced

Engineering Contradiction:
Improvegravity compensationVSAvoidmeasurement accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies local quality by providing counterbalancing force specifically at the first hinge location where gravitational torque is most significant, rather than uniformly distributing counterweight effects throughout the system. The counterweight member is strategically positioned and configured to generate localized compensation that maintains overall measurement accuracy while effectively reducing operator workload.

Inventive Principle:
Principle #3Local quality

3Weight of moving object

If the AACMM is made portable with reduced weight, then flexibility is improved, but control and safety are worsened due to uncontrolled movements

Engineering Contradiction:
ImproveportabilityVSAvoidcontrol and safety
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by implementing a friction element that can provide friction torque to prevent uncontrolled movements of the first hinge before they occur. This friction element acts as a preliminary safety mechanism that maintains control and prevents injuries or damage while preserving the portability benefits of the reduced-weight AACMM design.

Inventive Principle:
Principle #9Preliminary anti-action

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 reduces operator fatigue, minimizes deformation of the first segment, enhances measurement accuracy, and reduces the risk of collisions, providing a safer and more precise measurement experience.

Implementation Method 1

configured to provide a counterbalancing torque to compensate for gravitational torque acting on the first hinge

Methodology Applied
Scientific EffectGravitational torque: Gravitation

Implementation Method 2

The counterweight member comprises a force-providing element, a static element and an internal support. The force providing element provides a force to the rotary element

Methodology Applied
Scientific EffectTorque: Torque

Implementation Method 3

The friction element is configured to provide friction torque to prevent uncontrolled movements of the first hinge

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4534948B1Coordinate measuring machine with counterweight member
Publication Date: 2025.12.31 HEXAGON INNOVATION HUB GMBH
  • EP4534948B1 patent drawingFigure 1
  • EP4534948B1 patent drawingFigure 2a~2c
  • EP4534948B1 patent drawingFigure 3a~3b

AI summary

The invention relates to a CMM (1) comprising, a base (10), articulated elements (11-16), a counterweight, internal sensors (70-76), a control unit and a probe. The counterweight is associated with a first segment (12) and hinge (11) and configured to provide a counterweight torque to the first hinge (11) having an opposite direction to a gravitational torque. The counterweight comprises a force-providing element and a mechanism. The mechanism comprises a static element mounted on an axis (110) of the first hinge (11) and a rotary element kinematically linked to the static element. The shape of the static element is configured to set the counterweight torque. The mechanism further comprises a internal support configured to interact with an interaction area of the first segment (12).