Coordinate Positioning Machine with Passive Metrology Coupling
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Solution Overview
Problem
Articulated robots suffer from cumulative positional errors due to their serial nature, leading to lower accuracy and repeatability compared to Cartesian machines, making them unsuitable for demanding applications requiring high precision.
Innovation Solution
A manufacturing system that integrates a coordinate positioning machine with a passive metrology arrangement, allowing the machine to be coupled to a higher-accuracy metrology system for specific operations, using a combination of drive and positioning arrangements to enhance precision within defined zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If articulated robots use multiple rotary joints to achieve flexibility and reach, then adaptability and working volume are improved, but cumulative positional errors increase and measurement precision deteriorates
Solution Approach 1:
A passive metrology arrangement acts as an intermediary measurement system that couples to the articulated robot. This separate metrology system (using methods like laser tracking or vision systems) provides independent, high-precision position measurements without being part of the robot's mechanical linkage, thereby avoiding cumulative errors while maintaining the robot's flexibility
Solution Approach 2:
The system separates the robot's mechanical function (providing flexibility and reach) from the measurement function (providing positional accuracy). The robot handles adaptation and working volume, while a distinct passive metrology arrangement handles precise measurement, allowing each subsystem to optimize its own performance without compromising the other
2Productivity
If articulated robots are used for demanding high-precision tasks, then productivity is improved, but the inherent cumulative errors reduce manufacturing precision
Solution Approach 1:
The passive metrology arrangement provides real-time or near-real-time feedback on the actual position of the robot's tool center point. This feedback is used to compensate for cumulative errors through software correction, allowing the robot to achieve high manufacturing precision while maintaining its productivity and flexibility
3Measurement precision
If calibration techniques are applied to reduce positional errors, then measurement precision is improved, but the complexity of calibration increases due to the serial nature of joints
Solution Approach 1:
Instead of attempting to calibrate the complex serial linkage of multiple rotary joints, the system introduces a passive metrology arrangement as an intermediary reference system. This metrology system provides direct, absolute position measurements that bypass the need for complex calibration of the robot's mechanical parameters, significantly reducing calibration complexity
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A manufacturing system comprises: a coordinate positioning machine (10) having a structure moveable within a working volume of the machine, a drive arrangement for moving the structure around the working volume, and a positioning arrangement for determining the position of the structure within the working volume with a first accuracy; and a metrology arrangement (30) to which the machine (10) is removably couplable, such that when the machine (10) is coupled to the metrology arrangement (30), with the structure being moved by the drive arrangement, the metrology arrangement (30) is able to measure the position of the structure with a second accuracy that is higher than the first accuracy.