Articulated Wrist Controller for CMM Probe Reorientation
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Solution Overview
Problem
Existing articulated wrists for reorienting measuring probes in coordinate measurement machines face limitations in precision and efficiency due to mechanical uncertainties and the need for separate reorientation steps, which increase measurement time and risk of collisions.
Innovation Solution
An articulating wrist with a support element, reorientable elements, and a wrist controller that operates in locked and free modes, allowing precise and simultaneous reorientation with the positioning platform, using angle encoders and actuators to achieve desired orientations within specified times, and optionally incorporating environmental sensors for improved accuracy and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the articulated wrist uses indexed rotation axes with locking mechanisms, then measurement precision is improved, but measurement time increases due to separate reorientation steps
Solution Approach 1:
The patent applies dynamics by enabling the rotation axes to operate in two modes: locked mode for precision measurements and free mode for continuous reorientation. The controller dynamically switches between these modes, allowing the wrist to move freely during repositioning without mechanical constraints, then lock for accurate measurements, thus reducing measurement time while maintaining precision
2Measurement precision
If the articulated wrist performs reorientation separately from positioning, then measurement accuracy is improved, but productivity decreases due to increased dead time
Solution Approach 1:
The patent merges positioning and reorientation operations by enabling the controller to command the positioning platform and articulated wrist to move simultaneously along synchronized trajectories. This combination eliminates dead time between operations while maintaining measurement accuracy through the locked/free mode mechanism, thereby improving productivity without sacrificing precision
3Productivity
If the articulated wrist operates in free mode for continuous reorientation, then productivity is improved, but measurement precision deteriorates due to mechanical uncertainties
Solution Approach 1:
The patent uses dynamics by implementing mode switching between locked and free operation. The controller commands the articulated wrist to operate in free mode during reorientation for high productivity, then switches to locked mode before measurements to eliminate mechanical uncertainties and ensure precision. This dynamic adaptation allows the system to optimize for either productivity or precision based on operational requirements
4Measurement precision
If the articulated wrist uses locking mechanisms for indexed positions, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies dynamics by implementing a controllable locking mechanism that can switch between locked and free modes. The locking mechanism provides indexed positions for precision measurements when engaged, but can be disengaged to allow continuous reorientation. The controller manages this dynamic behavior, enabling the system to maintain precision capabilities while reducing operational complexity through automated mode switching
Data Source
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AI summary
An articulating wrist for reorienting a measure probe relatively to a measuring apparatus, including a support element connectable to a positioning platform of a coordinate measuring machine, a first reorientable element pivotably connected to the support element for rotation about a first rotation axis, a first actuator, actuatable to cause the first reorientable element to turn about the first rotation axis, a first angle encoder configured to determine an angular position of the first reorientable element relative to the support element and to generate a time series of position values, characterized by a wrist controller receiving the time series of position values, determine in real time desired positions of the first reorientable element and command the first actuator to move towards the desired positions