Lidar Subframes and Phase Shifting for Power Distribution
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Solution Overview
Problem
Lidar systems face challenges in evenly distributing power consumption throughout the image capture process, leading to power supply noise, component heating, and reduced performance due to the use of a single longer burst of pulses.
Innovation Solution
The implementation of multiple subframes, where X/N pulses are emitted and accumulated in each subframe, spreading power consumption over time, and using phase shifting and motion compensation techniques to align and combine histogram data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single long burst of pulses is used for image capture, then the image capture process is completed quickly, but power supply noise increases and components overheat
Solution Approach 1:
The patent divides the image capture process into multiple subframes, each containing a subset of the total pulses. Instead of transmitting all X pulses in one continuous burst, the pulses are distributed across N subframes (X/N pulses per subframe). This segmentation reduces the instantaneous power consumption and heat generation in any single time window, while the cumulative effect across all subframes maintains the required signal quality and capture speed.
2Productivity
If a single long burst of pulses is used for image capture, then the image capture process is completed quickly, but power supply noise increases
Solution Approach 1:
The patent segments the pulse sequence into multiple subframes, distributing the power consumption over time. Each subframe generates less power supply noise individually, and the interleaved timing allows noise to dissipate between subframes, reducing cumulative noise impact while maintaining capture efficiency.
Solution Approach 2:
The patent employs periodic transmission of pulse bursts across multiple subframes with regular intervals. This periodic action allows power supply circuits to recover and stabilize between bursts, reducing noise generation while maintaining overall productivity through the repeated cycling of pulse transmission across N subframes.
3Temperature
If multiple subframes are used to distribute power consumption, then power supply noise and heating are reduced, but the complexity of data processing increases
Solution Approach 1:
The patent segments both the pulse transmission and the data processing into corresponding subframes. Each subframe's histogram data is processed and transferred independently, allowing for modular and systematic handling of data. This segmented approach, combined with phase shifting, actually simplifies the overall processing architecture by creating regular, predictable data flow patterns that can be efficiently managed through systematic combination of subframe results.
Solution Approach 2:
The patent combines histogram data from multiple phase-shifted subframes to reconstruct the complete depth information. By merging the partial histograms from N subframes with appropriate phase alignment, the system achieves the same measurement resolution as a single long burst while benefiting from distributed power consumption, thus managing complexity through systematic data integration.
4Temperature
If multiple subframes are used to distribute power consumption, then power supply noise and heating are reduced, but the time required for image capture increases
Solution Approach 1:
The patent uses periodic pulse bursts across multiple subframes with optimized timing and interleaved transmission. This periodic structure allows for efficient use of time by maintaining regular transmission intervals while distributing the total pulse count across N subframes, thus reducing peak power demands without proportionally increasing total capture time.
Solution Approach 2:
The patent performs preliminary phase shifting and timing adjustments during the data acquisition phase, allowing for efficient combination of subframe results. By pre-planning the phase relationships and timing offsets between subframes, the system minimizes post-processing time and ensures that the extended capture time is optimized for maximum information gain while managing thermal and noise constraints.
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 reduces power supply noise, component heating, and improves lidar system performance by allowing power supplies to recover between bursts, increasing timing resolution, and reducing memory requirements while maintaining signal quality.
Implementation Method 1
Direct time-of-flight (dToF) measurement includes directly measuring the length of time between emitting radiation from emitter elements and sensing the radiation by sensor elements after reflection from an object or other target. The distance to the target can be determined from the measured length of time.
Implementation Method 2
Indirect time-of-flight measurement includes determining the distance to the target by phase modulating the amplitude of the signals emitted by the emitter elements of the lidar system and measuring phases (e.g., with respect to delay or shift) of the echo signals received at the sensor elements of the lidar system.
Data Source
AI summary
Systems, methods, and apparatus that can spread peak power dissipation (such as emitter power) in a lidar system over an increased range of time. Spreading the emitter power over time can provide several advantages. Dispersing the power supply noise and current spikes can reduce the load or stress on power supply components such as power transistors, decoupling capacitors, and others. Power supply noise and voltage drops can be reduced by allowing power supply decoupling capacitors time to recover between bursts of pulses. This can allow the use of lower-power transistors, smaller capacitors, and other changes that can conserve resources. Component heating, for example in the emitter array, can be reduced by providing time between bursts of pulses for device cooling. Lidar system performance can be improved since power supplies, bias lines, device temperatures, and other parameters have time to recover between the multiple smaller bursts of pulses, or subframes, as compared to a longer, single burst of pulses. Examples can utilize multiple subframes instead of a single frame. Using multiple subframes instead of a single frame can provide further advantages. Since histogram data can be moved out of the pixel circuits for each subframe, a reduced amount of memory can be needed in each pixel, thereby simplifying pixel circuitry. Further, by phase shifting subframe histogram data before combining, timing resolution of the combined histogram data can be increased. The linear regression, linear interpolation, or other method used to align the subframe data can provide a relative radial velocity between the lidar system and an object being imaged by the pixel.