SAR Interferometry Excavation Stability Monitoring
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Solution Overview
Problem
Existing methods for monitoring the stability of an excavation face, such as laser-based systems and radar interferometry, face challenges in accuracy and reliability due to environmental disturbances and movement of machinery, leading to potential false alarms and reduced effectiveness in detecting precursors to collapse.
Innovation Solution
A method using SAR interferometry that filters interferometric radar data to exclude disturbances caused by moving machinery, allowing for sub-millimeter accurate displacement measurements by calculating coherence values and applying mask coefficients to ensure reliable data, and combining with laser measurements for a three-dimensional representation of displacement data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radar interferometry is used to achieve sub-millimeter measurement accuracy, then measurement precision is improved, but reliability deteriorates due to disturbances from moving machinery
Solution Approach 1:
The patent extracts and removes the harmful interference components from the radar signal caused by moving machinery. By identifying and separating the signal components related to machinery movement from those related to excavation face displacement, the system preserves the high measurement precision of radar interferometry while eliminating the reliability-deteriorating disturbances.
Solution Approach 2:
The patent introduces an intermediary processing stage that analyzes the coherence of radar signals and selectively filters out components caused by moving machinery. This intermediary layer acts as a mediator between the raw radar data and the final displacement measurement, allowing the system to maintain sub-millimeter accuracy while improving reliability by excluding machinery-induced noise.
2Measurement precision
If laser-based monitoring systems are used to achieve high measurement accuracy, then measurement precision is improved, but ease of operation deteriorates due to the need for periodic repositioning of reflectors
Solution Approach 1:
The patent removes the requirement for physical reflectors by extracting the measurement function directly from the radar signal interference pattern. This eliminates the operational burden of installing, maintaining, and repositioning reflectors while preserving the high measurement precision capability through coherent radar interferometry.
Solution Approach 2:
The patent replaces the mechanical reflector-based laser measurement system with a radar-based electromagnetic wave interference system. This substitution eliminates the need for physical components that require manual positioning and maintenance, significantly improving ease of operation while maintaining measurement precision through the interferometric measurement principle.
3Measurement precision
If laser-based systems are used to achieve high measurement accuracy, then measurement precision is improved, but reliability deteriorates in the presence of dust and vapor
Solution Approach 1:
The patent replaces the optical laser-based system with a radar-based electromagnetic wave system. Radar waves have longer wavelengths and can penetrate dust and vapor that scatter or absorb optical light, thereby maintaining measurement precision and reliability in harsh excavation environments where laser systems deteriorate.
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
The method effectively filters out noise from moving machinery, providing accurate and reliable sub-millimeter displacement measurements, reducing false alarms, and enhancing the effectiveness of monitoring the stability of excavation faces.
Implementation Method 1
monitoring devices based on laser technology are currently used... by means of SAR (Synthetic Aperture Radar) interferometry... analyse the signal received by the radar sensor by means of interferometric technique
Data Source
Figure 1A~1B
Figure 2A~3
Figure 4
AI summary
A method for filtering an interferometric radar acquisition, said method comprising the step of prearrangement of a radar system for carrying out acquisitions of images of a scenario by means of SAR interferometry, said radar system comprising at least one radar sensor (110) arranged to emit and receive a radar signal, a control unit (115) configured to analyse said signal received by said radar sensor (110) by means of interferometric technique, a screen (120) arranged to show to a user said images of said scenario. The method then provides a step of periodic acquisition of images Si of said scenario for a number nc of cycles, with i = 1,2,...,nc, each image Si comprising a number np of pixels Pij having spatial coordinates defined with respect to a predetermined reference system, where Pij is the j-th pixel of the i-th image acquired at the i-th cycle, with j = 1,2,...,np . The method, at each i-th cycle and for each pixel Pij, further provides an iteration of the steps of calculation of a coherence value γij arranged to represent the quality of the phase information provided by a j-th pixel at the i-th cycle, comparison of said coherence value γij with a predetermined minimum coherence value γmin, interferometric calculation of a displacement value dij of said pixel Pij' said displacement value dij being zero in case that γij < γmin, and calculation of a cumulative displacement value Dij as the sum of the displacement values dij in the N cycles preceding said i-th cycle, said cumulative displacement value Dij being calculated according to the equation Dij=∑k=i−Nidkj.