Adaptive LIDAR Scan Pattern for Range Accuracy and Scan Rate
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Solution Overview
Problem
Existing LIDAR systems face challenges in achieving optimal scan patterns that balance integration time, sampling rate, and angle coverage to effectively map the environment around autonomous vehicles, while minimizing component degradation and ensuring accurate range and speed measurements.
Innovation Solution
A method and system for optimizing the scan pattern of a LIDAR system by determining maximum scan rates and minimum integration times based on signal-to-noise ratio (SNR) values, range, and angle ranges, using phase-encoded detection and chirped detection techniques to enhance range and speed accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If integration time is increased to improve range and speed accuracy, then measurement precision is improved, but productivity deteriorates due to slower scanning rate
Solution Approach 1:
The patent applies dynamics by making the scan pattern adaptive rather than fixed. The scanning system dynamically adjusts parameters including scan rate, integration time, and beam angle based on real-time environmental conditions, target characteristics, and measurement requirements. This allows the system to optimize between measurement precision and productivity for each specific scenario rather than using a constant scanning rate.
Solution Approach 2:
The patent changes multiple parameters simultaneously including integration time, scan rate, beam width, and scanning pattern based on the detected environmental conditions and measurement requirements. By coordinating changes in these parameters, the system achieves high measurement precision for critical areas while maintaining high productivity through faster scanning in less critical areas.
2Productivity
If scan rate is increased to improve productivity, then productivity is improved, but measurement precision deteriorates due to reduced integration time
Solution Approach 1:
The system dynamically adjusts integration time based on the current scan rate and environmental conditions. When scanning at high rates for productivity, the system increases integration time for specific measurements where precision is critical, such as detecting slow-moving objects or measuring long distances, while maintaining high overall scan rates.
Solution Approach 2:
The scanning field is segmented into different regions with different measurement requirements. The system applies longer integration times and slower scan rates to areas where high precision is needed (such as potential collision zones), while using shorter integration times and faster scan rates for areas where productivity is the priority, thereby achieving both goals simultaneously.
3Measurement precision
If high pulse power is used to achieve long range detection, then detection sensitivity is improved, but reliability deteriorates due to rapid degradation of optical components
Solution Approach 1:
The system uses periodic pulse transmission with variable duty cycles. Instead of continuous high power operation, the laser transmits in periodic pulses with adjustable duration and interval. This allows the optical components to be exposed to high peak power only during the brief pulse transmission, while remaining at lower power levels during the intervals, thereby reducing cumulative thermal stress and extending component lifespan.
Solution Approach 2:
The system dynamically changes pulse parameters including peak power, pulse duration, and repetition rate based on detection requirements and component thermal conditions. When long range detection is needed, the system uses higher peak power with appropriately shortened pulse durations. When components approach thermal limits, the system reduces peak power or increases pulse intervals to prevent degradation while maintaining detection capability.
4Measurement precision
If short pulse duration is used to improve range resolution, then measurement precision is improved, but productivity deteriorates due to lower peak power availability
Solution Approach 1:
The system uses periodic pulse transmission where short duration pulses are sent at optimized repetition rates. The short pulse duration provides excellent range resolution, while the periodic repetition allows the laser gain medium to fully regenerate between pulses, maintaining high peak power availability. The repetition rate is adjusted based on the balance between achieving sufficient peak power for detection and maintaining short pulse duration for resolution.
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
The optimized scan pattern allows for efficient environmental mapping of autonomous vehicles by improving range and speed accuracy, reducing component degradation, and enhancing collision avoidance capabilities.
Implementation Method 1
Optical detection of range using lasers, often referenced by a mnemonic, LIDAR, for light detection and ranging
Implementation Method 2
a signal reflected by a target and received by a receiving waveguide
Implementation Method 3
phase-encoded detection based on a sequence of single frequency phase changes
Implementation Method 4
chirped detection based on a frequency difference between a transmitted chirped optical signal and a returned signal
Implementation Method 5
detect Doppler shifts in returned signals that provide not only improved range but also relative signed speed
Implementation Method 6
using the same modulated optical carrier as a reference signal that is combined with the returned signal at an optical detector to produce in the resulting electrical signal a relatively low beat frequency
Data Source
AI summary
Techniques for optimizing a scan pattern of a LIDAR system including a bistatic transceiver include receiving first SNR values based on values of a range of the target, where the first SNR values are for a respective scan rate. Techniques further include receiving second SNR values based on values of the range of the target, where the second SNR values are for a respective integration time. Techniques further include receiving a maximum design range of the target at each angle in the angle range. Techniques further include determining, for each angle in the angle range, a maximum scan rate and a minimum integration time. Techniques further include defining a scan pattern of the LIDAR system based on the maximum scan rate and the minimum integration time at each angle and operating the LIDAR system according to the scan pattern.