Optical Beam Calibration for Non-Cartesian Positioning Machines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Calibration of non-Cartesian coordinate positioning machines, such as articulated robots, is challenging due to their complex geometry and the cumulative nature of positional errors in serial kinematic machines.
Innovation Solution
A system comprising a launch unit, a sensor unit, and a processor is used to calibrate non-Cartesian machines. The system launches an optical beam into the machine's working volume, and the sensor unit moves along the beam to measure transverse beam positions at multiple points, allowing the processor to derive the sensor unit's position relative to the beam in multiple degrees of freedom, thereby calibrating the machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used for non-Cartesian machines, then the calibration process is simple, but the positioning accuracy remains poor due to cumulative errors
Solution Approach 1:
An optical beam serves as an intermediary reference between the launch unit and sensor unit, enabling precise measurement of positional deviations without direct mechanical contact. The beam provides a stable reference that traverses the working volume, allowing calibration through optical measurement rather than complex mechanical comparison
Solution Approach 2:
The patent replaces traditional mechanical calibration methods with an optical measurement system. Instead of using mechanical artifacts or contact-based measurement, the system uses laser or optical beams to measure positions, eliminating mechanical error transmission and achieving higher precision in calibrating serial kinematic machines
2Adaptability or versatility
If serial kinematic architecture is used, then the machine has high flexibility and large reach, but positional errors accumulate along the kinematic chain
Solution Approach 1:
The calibration system measures actual positions of the sensor unit at multiple points along the optical beam and compares these measurements with the expected positions based on the kinematic model. This feedback information is used to identify and correct errors in the machine parameters, compensating for cumulative errors while maintaining the serial kinematic architecture's flexibility
Solution Approach 2:
The patent measures positions in multiple degrees of freedom (at least three) by detecting the optical beam at multiple measurement positions. This multi-dimensional measurement approach allows comprehensive characterization of positional errors throughout the working volume, enabling accurate calibration of the serial kinematic chain
3Measurement precision
If multiple measurement positions along the beam are used, then the positioning accuracy improves, but the calibration time increases
Solution Approach 1:
The system uses a sufficient number of measurement positions along the optical beam to achieve the required positioning accuracy. By strategically selecting measurement positions that provide maximum information about the kinematic errors, the calibration achieves high precision without unnecessarily increasing calibration time through excessive measurements
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
This method improves the positioning accuracy of non-Cartesian machines, making them suitable for use as coordinate measuring machines, and is applicable to various types of coordinate positioning machines beyond articulated robots.
Implementation Method 1
The sensor unit is operable, for each of the plurality of sensor unit positions, to measure a transverse beam position at a plurality of measurement positions along the beam
Data Source
AI summary
A system for calibrating or otherwise characterising a machine, including: a launch unit which is operable to launch an optical beam into a working volume of the machine; a sensor unit which is moveable by the machine to a plurality of sensor unit positions along the beam, and which is operable, for each of the plurality of sensor unit positions, to measure a transverse beam position at a plurality of measurement positions along the beam, with a position of the sensor unit relative to the beam in at least three degrees of freedom being derivable from the measurements; and a processor unit which is operable to use the measurements to calibrate or otherwise characterise the machine.