Coordinate Positioning Machine with Hexapod Metrology Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing coordinate positioning machines face challenges in achieving accurate positioning and movement within a working volume, particularly due to conflicts between drive and metrology arrangements that affect speed, accuracy, and cost considerations.
Innovation Solution
A coordinate positioning machine design that separates the metrology arrangement from the drive arrangement, utilizing a hexapod metrology arrangement for accurate position measurement in six degrees of freedom and a non-hexapod drive arrangement for rapid movement in fewer than six degrees of freedom, allowing for lightweight and fast movement with high accelerations while maintaining positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hexapod drive arrangement is used to move the structure in six degrees of freedom, then positioning accuracy is improved, but the drive mechanism becomes complex and expensive
Solution Approach 1:
The system is divided into two separate functional arrangements: a hexapod metrology arrangement dedicated to measurement and a non-hexapod drive arrangement dedicated to movement. This segmentation allows each subsystem to be optimized independently, reducing overall complexity while maintaining measurement precision.
Solution Approach 2:
The measurement function is extracted from the drive system. The hexapod metrology arrangement is separated from the drive mechanisms, allowing the drive system to be simpler and less expensive while the measurement system maintains high precision through its dedicated hexapod configuration with six length-measuring transducers.
2Measurement precision
If a hexapod drive arrangement with six actuators is used, then positioning accuracy is improved, but the speed and acceleration of the structure are reduced
Solution Approach 1:
The system separates measurement functions from drive functions. The hexapod metrology arrangement provides accurate position feedback without being involved in the actual movement, allowing the drive arrangement to operate at higher speeds and accelerations without the constraints of six heavy actuators.
Solution Approach 2:
The patent replaces a mechanical hexapod drive system with a non-hexapod drive arrangement (such as Cartesian or scara mechanisms) combined with a hexapod metrology system. This substitution allows faster, lighter drive mechanisms to be used while the hexapod transducers provide the necessary measurement precision through optical or other non-mechanical sensing methods.
3Measurement precision
If six length-measuring transducers are used in the hexapod arrangement, then measurement accuracy in six degrees of freedom is improved, but the cost of the machine increases
Solution Approach 1:
The measurement function is extracted and dedicated to a separate hexapod metrology arrangement. This allows the use of six precise length-measuring transducers solely for measurement purposes, while the drive system uses fewer, less expensive actuators. The separation enables cost-effective implementation by not requiring six expensive drive actuators with integrated measurement capabilities.
Solution Approach 2:
The patent uses the hexapod configuration specifically for metrology (measurement) rather than for driving. This creates a measurement copy of the hexapod principle that provides accurate six-degree-of-freedom positioning data without the cost and complexity of six full drive actuators, thereby reducing overall manufacturing cost while maintaining measurement accuracy.
4Speed
If the drive arrangement is constrained to fewer than six degrees of freedom, then the structure can move more rapidly with higher accelerations, but positioning accuracy in all six degrees of freedom may be compromised
Solution Approach 1:
The hexapod metrology arrangement provides continuous feedback on the position and orientation of the moveable structure in all six degrees of freedom. This feedback allows the control system to compensate for any deviations from the intended trajectory, maintaining positioning accuracy even though the drive arrangement operates with fewer degrees of freedom and higher speeds.
Data Source
AI summary
A coordinate positioning machine that includes: a structure moveable within a working volume of the machine, a hexapod metrology arrangement for measuring the position of the structure within the working volume, and a non-hexapod drive arrangement for moving the structure around the working volume. Also, a coordinate positioning machine including a structure moveable within a working volume of the machine, a drive arrangement for moving the structure around the working volume in fewer than six degrees of freedom, and a metrology arrangement for measuring the position of the structure within the working volume in more degrees of freedom than the drive arrangement.