Bistatic Radar Time-of-Flight Imaging System
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Solution Overview
Problem
Current imaging systems, such as millimeter wave imaging, require extensive scanning and large detector arrays for high resolution, and often make assumptions about the object's electrical boundary, limiting their efficiency and accuracy in reconstructing target objects.
Innovation Solution
The use of bistatic radar sensors to transmit and measure electromagnetic waves, determining time of flight estimates, and creating an image model to draw candidate surface portions and assign weights, allowing for the definition of an estimated surface without assuming the object's electrical boundary, using techniques like Orthogonal Matching Pursuit for sparse estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If holographic reconstruction with rotational scanning is used, then image quality is improved, but scanning time increases significantly
Solution Approach 1:
The patent segments the continuous rotational scanning process into discrete measurement positions. Instead of continuously rotating the detection arm, the system takes measurements at specific angular positions, reducing the time required while maintaining sufficient data for image reconstruction through sparse aperture techniques
Solution Approach 2:
The patent applies partial action by using a limited number of measurement positions rather than full rotational scanning. The sparse aperture approach uses fewer spatial samples than traditional methods, yet still achieves acceptable image quality by focusing computational resources on reconstructing the most critical object features
2Measurement precision
If focal plane array imaging is used for high resolution, then image resolution is improved, but the number of detectors required increases
Solution Approach 1:
The patent replaces the mechanical detector array system with an electromagnetic wave-based measurement system. Instead of using numerous physical detectors arranged in a focal plane array, the system uses radar sensors to transmit and receive electromagnetic waves, with image reconstruction performed through computational algorithms rather than direct detector sampling
Solution Approach 2:
The patent transitions from a two-dimensional detector array to a three-dimensional measurement approach by incorporating time-of-flight information. This adds the time dimension to the spatial measurements, enabling depth resolution without requiring additional detectors in the traditional focal plane array configuration
3Measurement precision
If inverse scattering techniques are used, then surface imaging capability is improved, but assumptions about electrical boundary are required
Solution Approach 1:
The patent changes the fundamental measurement parameter from assuming electrical boundary properties to measuring time-of-flight directly. By timing the round-trip travel of electromagnetic waves, the system determines surface geometry without needing to assume or know the electrical characteristics (conductivity, permittivity) of the target object, making the technique applicable to diverse materials
4Measurement precision
If diverging beams with large aperture are used, then cross-range resolution is improved, but field of view requirement increases
Solution Approach 1:
The patent introduces dynamic positioning of the radar sensors, allowing the system to achieve high cross-range resolution through multiple measurements at different sensor positions. Instead of using a static large aperture, the system dynamically moves sensors to capture data from multiple angles, synthesizing a large effective aperture through processing rather than physical size
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 enables efficient and accurate imaging of target objects with reduced scanning time and without assuming the object's electrical boundary, improving resolution and reflectivity estimation, as demonstrated by simulations and experiments with various targets.
Implementation Method 1
determine time of flight estimates based on the measured electromagnetic waves
Implementation Method 2
measure the electromagnetic waves reflected from the surface of the target object
Data Source
AI summary
An imaging system as disclosed can include multiple bistatic radar sensors configured to transmit electromagnetic waves towards a surface of a target object and configured to measure the electromagnetic waves reflected from the surface of the target object. The imaging system includes a computing device that determines time of flight estimates based on the measured waves. The computing device can draw, within an image model for the target object, multiple candidate surface portions of the surface of the target object based on the TOF estimates and predetermined positions of the bistatic radar sensors. Further, the computing device can assign weights to the candidate surface portions. The computing device can determine points where the candidate surface portions meet with a predetermined probability based on the weights. The computing device is configured to define an estimated surface of the target object in the image model based on the determined points.