Rotatable Grip Assembly for Portable CMM Operator Positioning
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Solution Overview
Problem
Conventional coordinate measuring machines (CMMs) face challenges in achieving accurate measurements due to variability in operator-induced loads and hand positioning, which complicates calibration and affects measurement accuracy.
Innovation Solution
The implementation of a coordinate measuring machine with a rotatable grip assembly that allows for easy and ergonomic handling, reducing frictional forces and providing consistent operator positioning, coupled with a counterbalance system to mitigate weight-related difficulties and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fixed grip designs are used, then the structure is simple, but operator-induced loads and hand positioning variability reduce measurement accuracy
Solution Approach 1:
The grip assembly is made rotatable about the longitudinal axis of the transfer member, allowing it to rotate dynamically as the operator moves their hand during positioning. This dynamic capability enables the operator to maintain a consistent grip orientation while moving through different positions, reducing variability in operator-induced loads and improving measurement accuracy without requiring complex active control systems
Solution Approach 2:
The rotatable grip assembly serves itself by automatically adjusting its rotational position as the operator naturally moves their hand during operation. The grip rotates passively with operator movement rather than requiring active control mechanisms, sensors, or motors, thereby improving measurement consistency while keeping the device structure relatively simple
2Ease of operation
If operator hands are positioned at various locations along the arms, then ease of operation is improved, but calibration difficulty increases due to varying loads
Solution Approach 1:
The rotatable grip allows the operator's hand to move freely to various locations along the transfer member while maintaining a consistent grip orientation. The grip rotates dynamically with hand movement, ensuring that the operator always grips in the same rotational position regardless of location, which maintains ease of operation while reducing calibration complexity by eliminating variability in grip orientation
Solution Approach 2:
The invention changes the rotational position parameter of the grip dynamically as the operator moves to different locations. By allowing the grip to rotate to different angular positions corresponding to different hand locations, the system maintains consistent operator interaction characteristics throughout the range of motion, simplifying calibration while preserving operational flexibility
Data Source
AI summary
A portable coordinate measuring machine (PCMM) can have one or more rotatable grip assemblies to provide a location for an operator to grasp the PCMM. A rotatable grip assembly can include a rotatable sleeve, a grip portion disposed over the sleeve, and one or more retaining rings to prevent the rotatable grip from axially sliding along one or more members of an articulated arm PCMM. A PCMM can include two rotatable grips to allow an operator to grasp the PCMM with both hands for positioning and repositioning operations. One rotatable grip can be positioned on an arm member most distant the PCMM base, and another rotatable grip can be positioned on a housing at least partially encasing an articulating joint assembly coupled to the arm member most distant the PCMM base. Other numbers of and locations of rotatable grip assemblies can be used in PCMMs.