Automotive Radar Phase Displacement Detection
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Solution Overview
Problem
Current automotive radar systems using FMCW or Fast-FMCW schemes have limited range resolution, making it difficult to detect small motions such as a person waving their hand, as the range resolution is too coarse compared to the magnitude of the object's motion, leading to undetectable motion and incorrect detection of a person as stationary.
Innovation Solution
An object sensing device with a transmitter and receiver that uses a periodically swept RF frequency signal, generating an IF signal by mixing the transmission and reception signals, and detecting target position based on amplitude and displacement based on phase changes in the IF signal, allowing for the detection of moving bodies without complex processing or special devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FMCW or Fast-FMCW scheme is used for object detection, then the detection system can identify targets at a distance, but the range resolution is limited to about 0.3m, making small motions undetectable
Solution Approach 1:
The patent segments the detection process into two independent components: position detection using amplitude information and displacement detection using phase information. By separating these functions, the system can detect both the location and motion of objects independently, overcoming the limitation where small motions were undetectable due to coarse range resolution.
Solution Approach 2:
The patent introduces a new dimension of phase information to complement the traditional amplitude-based range detection. While amplitude provides position information with resolution limited by bandwidth, phase provides an additional dimension that can detect displacements much smaller than the range resolution, effectively adding a fine-resolution measurement channel.
2Measurement precision
If bandwidth is increased to improve range resolution, then detection precision improves, but system complexity and cost increase
Solution Approach 1:
The patent uses phase information as an intermediary to achieve high-resolution displacement measurement without requiring high bandwidth. The phase of the IF signal serves as a mediator that encodes fine displacement information, allowing the system to achieve high measurement precision while maintaining moderate bandwidth and avoiding the complexity associated with ultra-wideband systems.
3Measurement precision
If phase information is used for displacement detection, then motion detection sensitivity improves, but signal processing complexity increases
Solution Approach 1:
The patent employs dynamic tracking of phase changes over time to detect displacement. By continuously monitoring the phase of the IF signal and comparing it across different time points, the system achieves high sensitivity to motion while using relatively simple processing operations that track temporal variations rather than requiring complex simultaneous computations.
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 the detection of moving bodies with improved resolution, distinguishing between stationary and moving targets, even when the motion is smaller than the traditional range resolution, enhancing safety in autonomous driving applications.
Implementation Method 1
a transmitter (10) that transmits a radio wave
Implementation Method 2
a receiver (20) that receives a reception signal (u0(t)) which is a reflected wave of the transmission signal (u(t)) reflected by the target (403)
Implementation Method 3
an IF signal generation unit (202) that generates an IF signal by mixing the RF transmission signal with the RF reception signal
Data Source
AI summary
The object sensing device comprises a transmitter and a receiver. The transmitter includes an irradiation unit that irradiates an RF transmission signal having a periodically swept frequency. The receiver includes a reception unit that receives an RF reception signal being a reflected wave of the RF transmission signal reflected by the target, an IF signal generation unit that generates an IF signal by mixing the RF transmission signal with the RF reception signal, a position detection unit that detects a position of the target, based on amplitude of a one-dimensional spectrum calculated from the IF signal for each period in which the frequency is swept, and a displacement detection unit that detects displacement of the target, based on a phase of the one-dimensional spectrum at the detected position of the target.