Pulsed-Light Ranging Using Inflection Point Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pulsed-light detection and ranging systems face inaccuracies in distance calculations due to signal saturation, which renders peak detection methods impractical, and requires calibration based on signal strength and waveform integrity.
Innovation Solution
A pulsed-light detection and ranging apparatus and method that calculates distance using the inflection point of a pulse's rising edge, employing a tangent calculator to determine the x-intercept, allowing for accurate ranging regardless of signal saturation and amplitude, and simplifying mathematical operations for precise distance calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If peak detection methods are employed to calculate time of flight, then distance measurement can be performed, but signal saturation renders the method impractical and inaccurate
Solution Approach 1:
The patent changes the parameter used for time-of-flight calculation from peak detection to inflection point detection. The inflection point is identified by detecting where the second derivative of the signal changes sign, which occurs at a consistent position on the rising edge of the pulse regardless of saturation level. This parameter change allows accurate ranging even when the pulse amplitude is saturated.
Solution Approach 2:
The patent replaces the mechanical/physical requirement of receiving a complete, unsaturated pulse waveform with a mathematical signal processing approach. By using derivative-based inflection point detection, the system substitutes the need for intact pulse waveforms with a computational method that extracts timing information from the signal's mathematical properties, making it immune to amplitude saturation.
2Measurement precision
If calibration based on output power level and signal amplitude is performed, then accurate ranging can be achieved, but system complexity and calibration requirements increase
Solution Approach 1:
The patent implements a self-service approach where the system automatically determines the inflection point timing without requiring external calibration data. The method uses the signal's own mathematical properties (second derivative sign change) to identify the timing point, eliminating the need for separate calibration procedures to establish relationships between amplitude, power level, and timing.
Solution Approach 2:
The patent extracts only the essential timing information from the pulse signal by focusing on the inflection point on the rising edge, separating this critical parameter from the rest of the pulse waveform characteristics. This extraction approach discards the need to process or calibrate based on pulse amplitude, width, or other waveform properties that would otherwise require calibration.
3Measurement precision
If complete pulse waveforms are required for accurate time of flight calculation, then measurement accuracy is maintained, but the dynamic range of detectable signals is limited
Solution Approach 1:
The patent applies partial action by using only the rising edge portion of the pulse containing the inflection point, rather than requiring the complete pulse waveform. This partial use of the signal allows the system to process saturated pulses where only the leading edge is reliably detectable, significantly expanding the dynamic range while maintaining sufficient accuracy for time-of-flight measurement.
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
Enables accurate object ranging with increased dynamic range and reduced processing overhead, eliminating the need for proper pulse waveform reception and calibration, facilitating faster and more precise distance measurements.
Implementation Method 1
Light pulses reflected from an object in the scene are received by the detection device and converted to an electrical signal
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A pulsed-light detection and ranging apparatus comprises an optical detector arranged to generate, when in use, time-series data in response to an optical pulse incident thereupon. A processing resource is also provided and arranged to support a pulse analyser (132). The pulse analyser (132) is arranged to identify (134) an inflection point of a pulse described by the time-series data. The pulse analyser (132) is further arranged to calculate (138) a distance based upon determined inflection point relative to a time axis associated with the time-series data.