Hybrid Solid-State LiDAR Control for SPAD Dynamic Range
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Solution Overview
Problem
Conventional SPADs-based lidars suffer from dynamic range limitations, leading to reflectivity signal loss in short-range measurements and inadequate sensitivity in long-range applications, constraining their adaptability in complex environments.
Innovation Solution
A hybrid solid-state lidar with power-and-pulse-width-adjustable VCSELs and a control method that dynamically adjusts emission parameters within a single ranging cycle, incorporating a rotating polygon mirror and SPADs array sensor, to expand the signal dynamic range and enhance measurement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SPADs are used for detection, then single-photon detection capability is achieved, but dynamic range is limited causing saturation in short-range measurements
Solution Approach 1:
The patent applies dynamics by making the laser emission parameters (power and pulse width) adjustable and variable during the measurement process. The control unit dynamically selects different emission parameters based on the measurement requirements, transforming the static SPADs-based system into a dynamic one that can adapt to different ranging distances and signal intensities, thereby resolving the contradiction between detection sensitivity and dynamic range.
Solution Approach 2:
The patent implements parameter changes by varying the power and pulse width of laser emissions across multiple emission cycles. By changing these parameters, the system generates echo signals with different intensities that are then accumulated to reconstruct the point cloud. This approach expands the effective dynamic range of the SPADs detector without requiring hardware modifications.
2Adaptability or versatility
If multiple measurements are accumulated to increase dynamic range, then signal coverage improves, but measurement time increases
Solution Approach 1:
The patent applies continuity of useful action by performing multiple laser emissions and accumulating echo signals within a single measurement cycle rather than requiring multiple separate measurement cycles. This continuous accumulation process maintains high temporal resolution while expanding the effective dynamic range, thereby reducing the total measurement time compared to conventional approaches.
3Device complexity
If fixed emission parameters are used, then system simplicity is maintained, but measurement accuracy varies across different ranges
Solution Approach 1:
The patent implements parameter changes by using a control unit that adjusts laser power and pulse width based on the target distance and required measurement accuracy. This allows the system to optimize measurement precision for both short-range and long-range targets while maintaining relatively simple hardware architecture, resolving the contradiction between system simplicity and measurement accuracy.
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 solution suppresses short-range saturation while improving long-range sensitivity, ensuring high accuracy for both short- and long-range measurements without increasing hardware complexity or accumulation cycles, thus enabling reliable perception in complex scenarios.
Implementation Method 1
N power-and-pulse-width-adjustable vertical cavity surface emitting lasers (VCSELs)
Implementation Method 2
single photon avalanche diodes (SPADs) array sensor
Implementation Method 3
a rotating polygon mirror... reflecting, by a rotating polygon mirror, the detection laser beams to form detection scanning beams
Implementation Method 4
precise measurement of the time-of-flight (ToF) of laser pulses, which calculates the time difference between emission and reception to obtain target distance information
Data Source
AI summary
The present disclosure provides a hybrid solid-state lidar with an increased signal dynamic range and a control method. The hybrid solid-state lidar includes: a laser transmitter unit, a laser receiver unit, a transmitting mirror, a receiving mirror, and a rotating polygon mirror, where the laser transmitter unit includes multiple power-and-pulse-width-adjustable vertical cavity surface emitting lasers (VCSELs); the laser receiver unit adopts a single photon avalanche diodes (SPADs) array sensor; and the laser transmitter unit performs at least one emission cycle during a single measurement. By dynamically adjusting emission parameters within a single ranging cycle, the present disclosure expands the signal dynamic range in a time coherent single photon counting (TCSPC) process, enhancing measurement precision of the lidar in both long-and short-range ranging.