Common-Axis LIDAR-Radar Scanning for Deformation Mapping
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Solution Overview
Problem
Existing structural monitoring methods face challenges such as the difficulty in installing optical reflectors on historic or hard-to-reach structures, operational complexity in combining radar and laser data, and limitations due to phase ambiguity and partial coverage overlap, leading to inaccurate and inefficient deformation measurements.
Innovation Solution
A method integrating SAR interferometry with laser scanning, using a combined LIDAR and radar sensor system that rotates simultaneously around a common axis, allowing simultaneous data acquisition and alignment, and includes a disambiguation step to overcome phase ambiguity, enabling precise three-dimensional mapping and displacement vector calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical reflectors are installed on structures for laser monitoring, then measurement accuracy of about 1 mm is achieved, but installation becomes operationally onerous and difficult on historic or hard-to-reach structures
Solution Approach 1:
The invention extracts the measurement capability from the structure by using radar interferometry that measures displacement of the structure itself through its natural reflectivity, eliminating the need to attach external reflectors to the monitored structure. The radar system measures the phase difference of signals reflected directly from the structure surface.
Solution Approach 2:
The radar system serves multiple functions: it monitors deformation without requiring installation on the target structure, works on any surface with natural reflectivity, and provides both displacement magnitude and direction information through interferometric phase measurement.
2Adaptability or versatility
If independent radar and laser systems are used for monitoring, then both technologies can be applied, but data combination requires high operational complexity and systematic error correction
Solution Approach 1:
The invention merges radar and laser systems into a single integrated platform with a common support structure and shared spatial reference system. Both sensors are mounted on the same moving platform and rotate together around the same axis, ensuring that all measurements are automatically referenced to the same coordinate system without requiring complex alignment procedures.
Solution Approach 2:
The common support structure acts as an intermediary that couples the radar and laser systems, providing a rigid mechanical reference frame that automatically synchronizes their spatial coordinates. This mechanical coupling eliminates the need for complex mathematical transformations between different coordinate systems.
3Adaptability or versatility
If independent radar and laser systems are used with different viewpoints, then both technologies operate independently, but coverage overlap is only partial and monitoring is limited to areas where both data are available
Solution Approach 1:
By merging radar and laser systems on a common platform with identical rotation axis and spatial reference, the invention creates a unified measurement system where both sensors observe the exact same areas simultaneously, maximizing coverage overlap and eliminating gaps in monitoring coverage.
4Measurement precision
If interferometric radar is used for monitoring, then sub-millimeter accuracy is achieved, but phase ambiguity limits measurement to displacements less than a quarter of the wavelength
Solution Approach 1:
The laser system acts as an intermediary that provides unambiguous displacement measurements along the laser line of sight. This independent measurement channel resolves the phase ambiguity of the radar system by providing a reference that does not suffer from the same wavelength limitations, allowing the radar to accurately measure larger displacements when combined with the laser data.
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 approach provides precise, efficient, and comprehensive deformation monitoring with improved data superimposition and reduced computational time, overcoming phase ambiguity and alignment errors, while allowing for intuitive visualization and accurate displacement measurement.
Implementation Method 1
a LIDAR sensor; during said step of rotating said LIDAR sensor, laser scanning of said scenario, obtaining a three-dimensional model comprising a plurality of points Pl
Implementation Method 2
a radar sensor; during said step of rotating said radar sensor, radar scanning of said scenario, obtaining at least two matrices of complex data comprising information of amplitude and phase
Implementation Method 3
rotating said LIDAR sensor about said rotation axis z, by means of said or each actuator; rotating said radar sensor about said rotation axis z, by means of said or each actuator
Data Source
AI summary
A method for monitoring the deformation of a scenario comprising a first step of prearranging a device (100) for monitoring the deformation of a scenario comprising a support (105), a LIDAR sensor (110), a radar sensor (120), at least one actuator arranged to move the LIDAR sensor (110) and the radar sensor (120) with respect to the support (105). The method then comprises the steps of defining a spatial reference system S comprising a rotation axis z, integral with the support (105), rotating the LIDAR sensor (110) about its rotation axis z, and contemporaneous laser scanning of the scenario, obtaining a three-dimensional model comprising a plurality of points Pl of the scenario. The method also comprises the steps of rotating the radar sensor (120) about its rotation axis z, and contemporaneous radar scanning of said scenario, obtaining at least two matrices of complex data comprising information of amplitude and phase of a plurality of points Pr. The method also comprises the steps of focusing the at least two matrices of complex data obtaining at least two focused images of the scenario, comparing the at least two focused images of the scenario obtaining a relative interferogram and generating a three-dimensional map of the scenario superimposing the relative interferogram with the three-dimensional model in such a way that points Pl and Pr having the same spatial coordinates with respect to the spatial reference system S are superimposed to each other.