Lidar Signal Processing for Same-Speed Target Differentiation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lidar devices struggle to distinguish between scattered light from near and far observation targets when their moving speeds are the same, leading to overlapping frequencies and inability to detect the presence of both targets accurately.
Innovation Solution
The proposed solution involves generating multiple light pulses with distinct optical frequencies, allowing the lidar device to differentiate between scattered light from different targets by employing a pulse modulating unit, optical multiplexing, and signal processing techniques to calculate the Doppler frequency and relative speeds of each target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional lidar device uses a single optical frequency for light pulses, then the device structure is simple, but it cannot distinguish between scattered light from near and far observation targets when their moving speeds are the same
Solution Approach 1:
The patent applies parameter changes by varying the optical frequency parameter of light pulses across different radiation cycles. The pulse modulating unit assigns different optical frequencies to light pulses radiated in different cycles, enabling the signal processing device to distinguish between scattered light from near and far targets by detecting these frequency differences, even when their Doppler frequencies are identical.
Solution Approach 2:
The patent implements periodic action through the pulse modulating unit that repeatedly radiates light pulses with different optical frequencies in different radiation cycles. This periodic variation of optical frequencies allows the system to differentiate between targets at different distances by analyzing the temporal and spectral characteristics of returned scattered light across multiple cycles.
2Productivity
If the lidar device radiates light pulses at short intervals, then the productivity is improved, but scattered light from far targets may overlap with light pulses from subsequent radiation cycles
Solution Approach 1:
The patent resolves the overlap problem by changing the optical frequency parameter. When scattered light from far targets returns after subsequent light pulses are radiated, the pulse modulating unit ensures that each radiation cycle uses a distinct optical frequency. The signal processing device then identifies the correct scattered light by matching the frequency of received light with the expected frequency for that radiation cycle, preventing misidentification despite temporal overlap.
Solution Approach 2:
The optical frequency acts as an intermediary identifier that links each scattered light signal to its corresponding radiation cycle. By encoding the radiation cycle information into the optical frequency of light pulses, the system creates a unique signature for each cycle's scattered light, enabling the signal processing device to correctly attribute returned signals to their source cycles even when pulses are radiated at short intervals.
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 accurate calculation of the moving speeds of both near and far observation targets even when their scattered light overlaps, effectively resolving the differentiation issue in conventional lidar devices.
Implementation Method 1
a light source that outputs a laser beam
Implementation Method 2
calculates a Doppler frequency due to movement of each observation target from an optical frequency of each multiplexed light
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A signal processing device (15) is configured to calculate, as a moving speed of each of a plurality of observation targets present in a space, a relative speed of each of the observation targets with respect to a lidar device. A plurality of light pulses having different optical frequencies from each other are generated from a laser beam output from a light source (1), each of the light pulses radiated to the space and then scattered by each of the observation targets is received as scattered light, and multiplexed light of each of the scattered light and the laser beam is detected. The signal processing device (15) includes: a Doppler frequency calculating unit (16) to calculate a Doppler frequency that is included in an optical frequency of each of the scattered light and due to movement of each of the observation targets from the optical frequencies of the plurality of generated light pulses and a detection signal of each of the multiplexed light; and a speed calculating unit (17) to calculate a relative speed of each of the observation targets from each of the Doppler frequency calculated by the Doppler frequency calculating unit (16).