Pulse Width Modulated Distance Detection System
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical rangefinders face challenges in accurately measuring distance and resolving signal noise ratio, particularly in adverse weather conditions, due to limitations in existing digital processing techniques that do not adapt to varying range-dependent needs.
Innovation Solution
A method that uses pulse width modulated visible-light sources for illumination, integrating reflection energy at different time periods to calculate a propagation delay value, which determines the distance to an object, while optimizing parameters such as accumulation and phase shift techniques based on the range to improve resolution and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional threshold-based detection is used, then the system can detect objects with weak signal reflection, but the system generates false alarms from transient noise
Solution Approach 1:
The system uses feedback by continuously monitoring the received signal and adjusting the threshold dynamically based on the statistical characteristics of the background noise and signal distribution. The threshold is adapted according to the detected signal strength and noise level, allowing the system to maintain high detection sensitivity while suppressing false alarms from transient noise.
Solution Approach 2:
The detection threshold is made dynamic rather than fixed. The system adapts the threshold in real-time based on the observed signal characteristics and noise conditions, enabling optimal performance across varying environmental conditions while maintaining both sensitivity and reliability.
2Reliability
If the threshold is set high to avoid false alarms, then the system avoids false alarms, but the system cannot detect objects that return weak signal reflection
Solution Approach 1:
The threshold is dynamically adjusted based on the detected signal characteristics. When weak reflections are detected, the threshold is lowered to enable detection, while when noise levels are high, the threshold is raised to avoid false alarms. This dynamic adaptation resolves the contradiction between avoiding false alarms and detecting weak signals.
Solution Approach 2:
The system changes the detection threshold parameter adaptively based on the observed signal-to-noise conditions. By modifying this critical parameter in response to changing environmental conditions, the system maintains optimal detection performance across different scenarios without being constrained by a fixed threshold setting.
3Measurement precision
If averaging technique is used to improve signal to noise ratio, then the signal to noise ratio is improved, but the response time increases and the system becomes too slow
Solution Approach 1:
Instead of applying full averaging over many samples, the system applies partial averaging only when necessary based on the detected signal-to-noise conditions. When the signal is strong and noise is low, minimal or no averaging is applied, maintaining fast response time. When the signal is weak or noise is high, averaging is applied to improve the signal-to-noise ratio.
Solution Approach 2:
The degree of averaging is made dynamic rather than fixed. The system adjusts the averaging window size and number of samples based on the real-time signal characteristics and noise conditions, enabling optimal balance between signal-to-noise improvement and response time for each specific detection scenario.
4Measurement precision
If clock pulse delay circuit technique is used to enhance resolution, then the resolution is improved by a factor N, but the number of averages required increases
Solution Approach 1:
The system applies the clock pulse delay circuit technique partially, using it to enhance resolution only when the range-dependent analysis indicates it is necessary. For detections where high resolution is not critical, the system uses standard processing, reducing the computational burden and number of averages required.
Solution Approach 2:
The high-resolution clock pulse delay technique is applied locally to specific distance ranges where it provides the most benefit. The system uses range-dependent analysis to determine when high resolution is needed and applies the technique selectively, rather than uniformly across all measurements, optimizing the trade-off between resolution and processing time.
5Measurement precision
If digital correlation is used to increase resolution, then the distance measurement resolution is increased, but the processing complexity increases
Solution Approach 1:
Digital correlation is applied locally to specific scenarios where high resolution is critical and the computational resources are available. The system uses range-dependent analysis to identify when correlation processing is necessary and applies it selectively, rather than to all measurements, reducing overall processing complexity while maintaining high resolution when needed.
Solution Approach 2:
The system applies digital correlation partially, using it only for measurements where the range-dependent analysis indicates high resolution requirements. For standard measurements, simpler processing methods are used, reducing the overall computational complexity and processing load on the system.
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 detection of objects and weather conditions, providing improved resolution, repetition rate, and adaptability to different applications, effectively addressing the limitations of conventional rangefinders in adverse weather.
Implementation Method 1
measuring the time a short pulse of light emitted from the apparatus takes to reach an object and be reflected to a photo-detection circuit
Implementation Method 2
integrating a reflection energy for a first time period from a time t−x to a time t+x
Data Source
AI summary
There is provided a system and method for detecting a distance to an object. The method comprises providing a lighting system having at least one pulse width modulated visible-light source for illumination of a field of view; emitting an illumination signal for illuminating the field of view for a duration of time y using the visible-light source at a time t; integrating a reflection energy for a first time period from a time t−x to a time t+x; determining a first integration value for the first time period; integrating the reflection energy for a second time period from a time t+y−x to a time t+y+x; determining a second integration value for the second time period; calculating a difference value between the first integration value and the second integration value; determining a propagation delay value proportional to the difference value; determining the distance to the object from the propagation delay value.