Articulated Arm CMM Counterweight for Gravity Torque Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing portable articulated arm coordinate measuring machines (AACMMs) face issues with excessive workload due to supporting heavy weights, non-natural postures, and potential for collisions, which can lead to injury or damage, while prior art counterweight members either increase weight or negatively affect accuracy.
Innovation Solution
A CMM with a counterweight member that provides a torque opposite to the gravitational torque acting on the first hinge, using a mechanism with a static element and rotary element to compensate for gravity, minimizing deformation and enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If prior art counterweight members are used to compensate gravity, then the workload is reduced, but the weight of the instrument increases
Solution Approach 1:
The patent applies the counterweight principle by introducing a counterweight member with mass that generates a torque opposite to the gravitational torque acting on the articulated elements. This counterweight member is positioned and configured to provide gravitational counter-torque, thereby compensating for the weight of the articulated elements and reducing the operator's workload without requiring motorized compensation systems.
2Ease of operation
If prior art counterweight members are used to compensate gravity, then the workload is reduced, but the measurement accuracy deteriorates
Solution Approach 1:
The patent applies local quality by positioning the counterweight member specifically at the first hinge location, where it provides localized gravitational counter-torque only where needed to compensate for the articulated elements' weight. This localized approach ensures that the counterweight does not interfere with the probe's measurement path or the overall instrument geometry, thereby preserving measurement accuracy while reducing workload.
Solution Approach 2:
The counterweight member acts as an intermediary element that mediates between the gravitational force acting on the articulated elements and the operator's manual control. By introducing this intermediate mass, the system transforms the direct gravitational burden into a balanced torque relationship, reducing operational difficulty without compromising the precision of measurements taken by the probe.
3Volume of moving object
If the articulated arm is designed with large accessible volume, then the measurement range increases, but the weight and torque requirements increase
Solution Approach 1:
The patent addresses the weight issue of large-volume articulated arms by incorporating a counterweight member that compensates for the gravitational torque generated by the elongated articulated elements. This allows the arm to achieve large accessible volume without requiring excessive motor power or creating unmanageable torque requirements, as the counterweight balances the gravitational forces acting on the extended segments.
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
Reduces operator workload, minimizes deformation of the first segment, and improves measurement accuracy by passively stabilizing the first hinge, reducing the risk of collisions and enhancing pose reproducibility.
Implementation Method 1
the requirements of ultra-high accuracy, low weight, large accessible volume, lead to a preferred embodiment in which the arm comprises a series of hinges and elongated cylinders allowing rotation about their axis
Implementation Method 2
The counterweight member is configured to provide a torque having opposite direction to a torque caused by weight of the articulated elements
Data Source
AI summary
A CMM comprising, a base, articulated elements, a counterweight, internal sensors, a control unit and a probe. The counterweight is associated with a first segment and hinge and configured to provide a counterweight torque to the first hinge 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 of the first hinge 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.