Radar Signal Processing for Moving Object Detection
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Solution Overview
Problem
Existing radar technologies face challenges in accurately sensing moving objects due to coarse distance resolution and difficulty in distinguishing between moving bodies and fixed objects, especially when they are close to each other.
Innovation Solution
An object sensing apparatus that emits periodic frequency-swept RF transmission signals, receives reflected waves, generates IF signals, and produces one-dimensional spectra with fixed object reflections removed, allowing for accurate position and displacement detection of moving objects by analyzing the amplitude and phase of these spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FMCW or Fast-FMCW radar scheme is used, then object sensing capability is achieved, but distance resolution is coarse (about 0.3 meters)
Solution Approach 1:
The patent segments the reflected wave signal into multiple frequency components through Fourier transform, analyzing each frequency component separately to determine distance. This segmentation of the signal processing approach enables fine distance resolution without requiring extremely large bandwidth, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent transitions from one-dimensional distance measurement to two-dimensional analysis by examining both frequency and time domains. By analyzing the phase difference across multiple frequency components, the system achieves high distance resolution through dimensional expansion in the frequency domain, avoiding the need for simple wideband signals.
2Measurement precision
If phase change observation is used to sense small movements, then movement detection capability is improved, but ability to distinguish moving body from fixed object is lost when they are near each other
Solution Approach 1:
The patent segments the distance spectrum into multiple frequency components and analyzes the phase characteristics of each segment independently. By comparing phase changes across different frequency segments, the system can distinguish between fixed objects (which show consistent phase across frequencies) and moving objects (which show differential phase changes), thereby preserving object distinction information while maintaining movement detection capability.
Solution Approach 2:
The patent introduces frequency domain analysis as an intermediary between signal reception and movement detection. By using frequency components as mediators, the system can separately analyze phase changes for movement detection while simultaneously using frequency-dependent phase patterns to distinguish moving objects from fixed objects, preventing information loss.
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
Enables precise sensing of moving bodies by improving distance resolution and differentiating between moving and fixed objects, even when they are near each other, thereby enhancing the accuracy of object detection in radar systems.
Implementation Method 1
a sensing method using radar technology has been known as a method for sensing an object
Implementation Method 2
receive a reflected wave of the RF transmission signal reflected by an object
Implementation Method 3
generate an IF signal in each of the periods by mixing the RF transmission signal and the RF reception signal
Implementation Method 4
the width of the distance that can be detected with these schemes is defined by discrete values each separated by c/(2BW) due to the property of the Fourier transform
Implementation Method 5
measure minute displacement of the sensed target objects by using the change in phase of the received signal
Data Source
AI summary
An object sensing apparatus 1 includes: an emission unit 11 configured to emit an RF transmission signal in each period; a reception unit 21 configured to receive a reflected wave of the RF transmission signal as an RF reception signal; an IF signal generation unit 22 configured to generate an IF signal by mixing the RF transmission signal and the RF reception signal; a one-dimensional spectrum generation unit 23 configured to generate a one-dimensional spectrum with respect to distance obtained using the object sensing apparatus as a reference, based on the IF signal, and use the generated one-dimensional spectrum to generate a one-dimensional spectrum with fixed object reflection removed, from which a signal component caused by a reflected wave from a fixed object present in an emission range has been removed; a position detection unit 24 configured to detect a position of an object other than the fixed object based on the amplitude of the one-dimensional spectrum with fixed object reflection removed; and a displacement detection unit 25 configured to detect displacement of the object other than the fixed object, based on the phase of the one-dimensional spectrum with fixed object reflection removed, which corresponds to the position of the object other than the fixed object.