Multi-Range Time-of-Flight Detection With Adaptive Pulse Widths
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Solution Overview
Problem
Existing LiDAR systems struggle to accurately detect objects at varying distances due to limitations in pulse width and readout time adaptation, leading to incomplete detection of reflected light pulses and inaccurate distance calculations.
Innovation Solution
A method and apparatus that utilize multiple pulses with varying widths and timing slots to detect objects at different ranges, allowing for partial overlap of detection ranges and dynamic adjustment of pulse width and readout times based on light attenuation and time-of-flight, using a pixel array with groups of pixels for accurate distance calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pulse width is used for LiDAR detection, then the system structure is simple, but the detection accuracy for objects at varying distances deteriorates
Solution Approach 1:
The patent divides the detection process into multiple segments by using different pulse widths for different distance ranges. The controller selectively applies short pulse widths for near objects and long pulse widths for distant objects, segmenting the detection task to maintain both system simplicity and detection accuracy across varying distances.
Solution Approach 2:
The system dynamically adjusts the pulse width based on the detected distance to the object. The controller changes the pulse width parameter in real-time according to the object's range, enabling the system to adapt to varying detection requirements without increasing structural complexity.
2Length of stationary object
If the pulse width is increased to detect distant objects, then the detection range is improved, but the detection precision for close objects deteriorates
Solution Approach 1:
The system dynamically adjusts pulse width based on object distance. For close objects, short pulse widths maintain high detection precision, while for distant objects, long pulse widths extend the detection range. The controller automatically selects the appropriate pulse width to optimize both precision and range for each detection scenario.
Solution Approach 2:
The patent changes the pulse width parameter according to the object's distance. By adjusting this critical parameter dynamically, the system achieves both extended detection range for distant objects and maintained precision for close objects, resolving the trade-off between range and precision.
3Length of stationary object
If the readout time is extended to capture reflected pulses from distant objects, then the detection range is improved, but the detection speed deteriorates
Solution Approach 1:
The system dynamically adjusts the readout time duration based on the object's distance. For distant objects, longer readout times capture the delayed reflected pulses, while for close objects, shorter readout times maintain fast detection speed. This dynamic adjustment resolves the contradiction between range and speed.
Solution Approach 2:
The patent changes the readout time parameter according to the object's range. By adjusting this temporal parameter dynamically, the system extends detection range for distant objects while preserving detection speed for close objects, eliminating the trade-off between these two performance metrics.
4Measurement precision
If multiple pulses with varying widths are used for multi-range detection, then the detection accuracy for objects at different distances is improved, but the device complexity increases
Solution Approach 1:
The patent implements a universal LiDAR system that can detect objects across multiple distance ranges using a single detector and light source. The controller provides multi-functionality by selectively applying different pulse widths and readout times, eliminating the need for separate detection systems for different ranges and thus not increasing overall device complexity.
Solution Approach 2:
The system achieves multi-range detection by changing operational parameters (pulse width, readout time) rather than adding physical components. This parameter-based approach maintains detection accuracy across different distances while avoiding the complexity increase that would result from multiple dedicated detection systems.
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 precise distance measurement of objects across multiple ranges by averaging detection values and compensating for light attenuation, improving accuracy and adaptability in various lighting conditions, including fog, while enhancing detection capabilities in augmented reality and face recognition systems.
Implementation Method 1
Due to the effect of time of flight, the reflected pulse 12 arrives back at the detector of the LiDAR system at a time delay 14, which is proportional to the distance between the LiDAR system and the detected object
Implementation Method 2
an active pixel sensor having a plurality of pixel elements each of which including at least one photodiode
Data Source
AI summary
A method for detecting distance of a distant object is provided. The method includes sending at least one first pulse of light towards an object, the at least one first pulse having a first pulse width configured to detect objects at a first range of distances, detecting within at least one first time slot the first pulse reflected by objects within the first range; sending at least one second pulse of light towards the object, the at least one second pulse having a second pulse width configured to detect objects at a second range of distances. The method further includes detecting within a second time slot the second pulse reflected by objects within the second range and determining distance of the object in accordance with the detection of the first and second pulses.