Moving Object Detection Using Doppler Coefficient Estimation
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Solution Overview
Problem
Existing moving object detection systems that use linearly changed transmission waves face challenges in accurately measuring the distance and velocity of objects with unknown velocities, as they rely on approximations that lead to errors due to time-dependent frequency differences between transmission and reception waves.
Innovation Solution
A moving object detection system that includes a transmission waveform setting section, a transmitting section, a receiving section, a Doppler coefficient estimating section, and an object detection section, which sets a transmission signal with a linearly changed frequency, receives and processes the reflected signal, estimates the Doppler coefficient by analyzing waveforms at present and past time points, and detects the object based on this information to accurately calculate distance and velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a frequency offset is given to the transmission radio wave in advance based on predicted Doppler shift, then the reception radio wave can be processed in a form equivalent to a stationary object, but the technique fails when the object velocity is unknown
Solution Approach 1:
The patent applies preliminary action by predicting the Doppler shift based on object acceleration and giving a frequency offset to the transmission radio wave in advance. This allows the reception radio wave to be processed in a form equivalent to a stationary object, improving detection accuracy for objects with predictable motion patterns.
Solution Approach 2:
The patent transitions from a static frequency offset approach to a dynamic approach by incorporating object acceleration into the Doppler shift prediction. The frequency offset is dynamically adjusted based on the predicted acceleration, enabling the system to adapt to objects with unknown but changing velocities.
2Adaptability or versatility
If the beat frequency is calculated by averaging up-chirp and down-chirp beat frequencies, then objects with unknown velocity can be detected, but time-dependent frequency differences cause measurement errors
Solution Approach 1:
The patent replaces the mechanical averaging process with a computational approach. Instead of simply averaging up-chirp and down-chirp beat frequencies, the system calculates the Doppler shift based on object acceleration and applies appropriate frequency offsets, thereby accounting for time-dependent frequency differences and improving measurement precision.
Solution Approach 2:
The patent changes the parameters used in beat frequency calculation by incorporating acceleration-based Doppler shift predictions. The frequency offset is dynamically adjusted based on predicted acceleration, allowing the system to maintain measurement precision while detecting objects with unknown velocities.
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 enhances the accuracy of distance and velocity measurements by accounting for time-dependent frequency differences, improving the precision of object detection without relying on approximations, thus effectively handling objects with unknown velocities.
Implementation Method 1
a transmission signal whose frequency is linearly changed
Implementation Method 2
the Doppler shift fdt, which occurs along with the movement of the object, is added to the frequency of a reception radio wave
Data Source
AI summary
A moving object detection system comprises: a transmission waveform setting section to set a transmission signal in such a way that a frequency of the transmission signal is linearly changed; a transmitting section to transmit the transmission signal; a receiving section to receive a reception signal resulting from a reflection of the transmission signal at an object; a Doppler coefficient estimating section to estimate a Doppler coefficient associated with a movement of the object by performing arithmetic processing on a waveform of the reception signal at a present time point and waveforms of the reception signal at one or more past time points, the one or more past time points being earlier than the present time point by one or more specified periods of time; and an object detection section to detect the object based on the transmission signal, the Doppler coefficient, and the reception signal.