Optical Pulse Distance Measurement Timing Error Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pulsed time-of-flight laser distance measuring techniques face significant timing errors due to varying amplitudes of reflected optical pulses, leading to inaccuracies in distance measurement, which existing solutions like AGC circuits and peak detectors fail to adequately address, especially under conditions of saturation or distortion.
Innovation Solution
A method and apparatus that utilize a processor to determine time domain parameters from detected optical pulses, convert these into correction values using a modeling approach, and apply these corrections to accurately measure distance, accounting for errors caused by both pulse amplitude variations and receiver channel electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed threshold level is used to detect optical pulses, then the detection process is simple, but timing errors occur due to varying pulse amplitudes
Solution Approach 1:
The patent changes the detection parameter from fixed threshold amplitude to time domain characteristics (rise time, fall time, width). By measuring these temporal parameters and using them to correct timing errors, the system achieves accurate distance measurement regardless of pulse amplitude variations, resolving the contradiction between simple detection and precise measurement.
2Measurement precision
If AGC circuit is used to adjust signal amplitude, then amplitude variation is reduced, but the circuit complexity increases and response speed decreases
Solution Approach 1:
The patent extracts only the necessary temporal information (time domain parameters) from the received signal without requiring complex amplitude adjustment circuits like AGC. By focusing solely on timing characteristics rather than amplitude normalization, the system achieves amplitude invariance with minimal additional circuitry, resolving the contradiction between amplitude consistency and circuit complexity.
3Measurement precision
If peak detector is used to measure maximum amplitude, then timing error can be compensated, but the technique fails when signal is saturated
Solution Approach 1:
The patent changes from using amplitude-based parameters (peak amplitude) to time-based parameters (rise time, fall time, width) for timing error compensation. These temporal parameters remain valid even when signals are saturated, as they depend on the pulse shape rather than absolute amplitude levels, thus resolving the contradiction between timing error compensation and saturation resistance.
4Measurement precision
If unipolar-to-bipolar converter is used to generate bipolar signal, then zero-crossing detection can be applied, but detection error increases due to signal distortions
Solution Approach 1:
The patent extracts timing information directly from the received unipolar signal's time domain characteristics without converting to bipolar form. By measuring rise time, fall time, and width directly from the original signal, the system avoids the distortions introduced by unipolar-to-bipolar conversion while still achieving accurate timing, resolving the contradiction between edge detection accuracy and signal distortion.
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 solution effectively reduces timing errors by using time domain parameters to correct for amplitude and circuit-related inaccuracies, providing more accurate distance measurements even in challenging environments such as those with saturation or varying signal conditions.
Implementation Method 1
transmitting an optical pulse towards a target
Implementation Method 2
measuring a time interval between the transmission and the detection of the optical pulse
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
There is provided an apparatus (300) for measuring a distance to a target (312), comprising: a transmitter (302) configured to transmit an optical pulse (310) towards the target (312), a receiver channel (304) configured to receive the optical pulse (310) reflected from the target (312), and a processor (306) configured to measure a time intervaf between the transmission and detection of the optical pulse (310) at a predefined amplitude threshold level (11OA, 110B), to determine a time domain parameter from the detected optical pulse (310) at one or more amplitude threshold levels (110A, 110B), to convert the time domain parameter value into a correction value by a conversion model; to correct a timing error in the measured time interval by the correction value, and to convert the error- corrected time interval into a distance to the target (312).