Lidar Sensor Range Walk Error Correction
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Solution Overview
Problem
Existing optical sensors using pulse transit time methods for distance measurement face errors due to varying object reflectivities and distances, leading to inaccurate distance calculations, and high-bandwidth amplifiers can exacerbate these issues with overdriving and non-monotonic behavior.
Innovation Solution
The optical sensor employs multiple trigger points for digital time measurement, allowing for the selection of the most accurate trigger point to reduce light-dark errors, and uses separate signal paths with different receivers and amplifiers to generate and evaluate received signals, thereby improving measurement accuracy and reducing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single threshold value is used to evaluate received signals, then the evaluation process is simple, but measurement accuracy deteriorates due to light-dark errors from varying object reflectivities
Solution Approach 1:
The evaluation process is segmented into multiple parallel signal paths, each with its own threshold value (first trigger point and second trigger point). This segmentation allows different threshold levels to handle different signal强度 scenarios, improving measurement accuracy while maintaining manageable complexity through modular architecture
Solution Approach 2:
The system changes the threshold parameter by providing multiple threshold values (first and second trigger points) instead of a single fixed threshold. This allows the evaluation to adapt to varying signal conditions caused by different object reflectivities, thereby reducing light-dark errors and improving measurement precision
2Measurement precision
If high-bandwidth amplifiers are used to reduce light-dark errors, then measurement accuracy improves, but the amplifiers overdrive and exhibit non-monotonic behavior making computational compensation difficult
Solution Approach 1:
The system dynamically selects which signal path (and corresponding trigger point) to use based on signal characteristics. The evaluation unit determines which of the first or second trigger points provides reliable measurement, adapting to varying signal conditions without requiring high-bandwidth amplifiers that suffer from overdrive issues
Solution Approach 2:
Multiple signal paths with different threshold values act as intermediaries between the received signal and the final distance measurement. This intermediary structure allows the system to process signals reliably without pushing amplifiers into non-monotonic operating regions, maintaining both accuracy and stability
3Measurement precision
If multiple trigger points are used to evaluate received signals, then measurement accuracy and light-dark error reduction improve, but device complexity increases
Solution Approach 1:
The signal evaluation is segmented into multiple parallel paths with different trigger points. This segmentation enables accurate distance measurement by providing multiple reference levels for comparison, while the modular parallel structure keeps the increased complexity organized and manageable
Solution Approach 2:
Multiple signal paths with different trigger points serve the universal function of distance measurement under varying conditions. Each path can handle different signal强度 scenarios, making the overall system universally applicable to various object reflectivities without requiring entirely different measurement approaches
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 significantly enhances the accuracy of distance measurements by minimizing light-dark errors and drift effects, allowing for precise distance determination even with objects of varying reflectivities and distances.
Implementation Method 1
The transmitter (5) emits light pulses (4), which are reflected back from an object (10) to a receiver (7)
Implementation Method 2
at least one receiver (7) which is designed to receive light pulses (4) reflected back from an object (10)
Data Source
Figure 1~2
Figure 3
Figure 4a~4c
AI summary
The invention relates to an optical sensor (1) for detecting objects (10) in a monitoring area, comprising a transmitter (5) emitting light pulses (4), at least one receiver (7) configured to receive light pulses (4) reflected back from an object (10), and an evaluation unit (9) in which a distance measurement value for the distance of the object (10) to the optical sensor (1) is determined from the time-of-flight (TTOF) of light pulses (4) from the transmitter (5) to an object (10) and back to the receiver (7). At least one received signal is generated by a light pulse (4) incident on the at least one receiver (7), which is evaluated with at least two trigger points (PT1, PT2), wherein a time measurement value (T1, T2) is generated by each trigger point (PT1, PT2). In the evaluation unit (9), only one of the time measurements (T1, T2) is used to determine the distance measurement value.