LiDAR Ranging With Multi-Level Signals To Resolve Dynamic Range Limits
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Solution Overview
Problem
Conventional LiDAR systems face challenges in accurately determining distances and reflectivity due to non-linearity introduced by pre-processing circuits when signal levels of reflected light signals fall outside the dynamic range, leading to errors in ranging operations, especially across varying measurement distances and reflectivity levels.
Innovation Solution
A LiDAR module that transmits multiple signals with different levels and a configured time gap, ensuring at least one reflected signal is within the dynamic range, allowing for accurate identification and processing of candidate signals to determine distances and reflectivity, even when others are outside the range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-processing circuits (amplifier and ADC) are used to improve noise immunity of ranging operation, then noise immunity is improved, but non-linearity is introduced when signal levels fall outside dynamic range, causing errors in ranging and reflectivity measurement
Solution Approach 1:
The patent changes the signal level parameter by transmitting multiple signals with different levels (first signal with higher level, second signal with lower level). This allows the system to adapt to different reflectivity conditions - when the first signal produces a reflected signal outside the dynamic range, the second signal with lower level keeps its reflected signal within the linear range, maintaining measurement precision while still benefiting from pre-processing noise immunity.
2Ease of operation
If a single signal level is transmitted to perform ranging operation, then the system is simple to operate, but it cannot accurately measure both close and far target objects with different reflectivity levels
Solution Approach 1:
The patent segments the measurement task by dividing it into multiple signal transmission operations with different signal levels. The first signal with higher level is optimized for detecting far or low-reflectivity targets, while the second signal with lower level is optimized for detecting close or high-reflectivity targets. This segmentation allows the system to cover a wider range of measurement conditions without requiring complex adaptive signal level adjustment during operation.
Solution Approach 2:
The patent makes the LiDAR system multi-functional by enabling it to accurately measure both close and far target objects with varying reflectivity levels using a fixed set of multiple signal levels. The controller selectively processes results from different signal levels based on detected signal characteristics, allowing the same hardware to universally handle diverse measurement scenarios without requiring physical reconfiguration.
3Adaptability or versatility
If multiple signals with different levels are transmitted to cover wider measurement range, then adaptability is improved, but device complexity increases due to additional signal configuration and processing
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple signals with different levels before the actual ranging operation. The controller has all necessary signals prepared in advance, and during operation, it simply selects and transmits the appropriate signal based on the measurement requirements. This eliminates the need for complex real-time signal level adjustment algorithms, reducing processing complexity while maintaining wide adaptability.
Solution Approach 2:
The patent uses a simplified processing approach by creating multiple copies of the basic ranging operation, each using a different pre-configured signal level. Instead of implementing a single complex adaptive signal processing algorithm, the system runs multiple simpler ranging operations in parallel or sequence, each with fixed signal parameters. This copying strategy reduces the complexity of individual processing paths while achieving comprehensive measurement coverage.
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 and robustness of distance measurements across a wider range of distances and reflectivity levels, reducing interference and improving the reliability of LiDAR systems in various operational conditions.
Implementation Method 1
detect signals comprising a reflected first signal and a reflected second signal generated based on reflection of respectively the first signal and the second signal by a target object
Data Source
AI summary
Method and system for performing ranging operation are provided. In one example, a transmitter is configured to transmit a first signal having a first signal level and a second signal having a second signal level, the second signal being transmitted after the first signal, the first signal and the second signal being separated by a time gap configured based on a minimum distance of a range of distances to be measured by the LiDAR module. The first signal level and the second signal level are configured based on the range of distances to be measured by the LiDAR module, a range of levels of reflectivity of a target object to be detected by the LiDAR module, and a dynamic range of a receiver circuit to receive the first signal and the second signal. Ranging operation can be performed based on the time-of-flight of at least one of the first signal or the second signal.