Optical Distance Measurement Using FPGA Time-Interpolated Sampling
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Solution Overview
Problem
Existing LIDAR systems used in unmanned vehicles lack sufficient measurement precision for complex environments, requiring improved techniques for distance measurement with enhanced precision, reduced cost, and lower power consumption.
Innovation Solution
The use of a Field-Programmable Gate Array (FPGA) to process analog pulse signals from light detection, achieving high time resolution and centimeter-level precision in distance measurement by digitizing analog signals and extracting timing information with picosecond-level resolution, without relying on high-speed analog-to-digital converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing LIDAR systems are used for distance measurement, then basic obstacle detection is achieved, but measurement precision is insufficient for complex environments
Solution Approach 1:
The patent replaces traditional high-speed analog-to-digital converters (ADCs) with an FPGA-based time-interpolation sampling system. The FPGA uses multiple clock signals with different phases to interpolate timing measurements between clock edges, achieving picosecond-level time resolution without requiring gigasample-per-second ADC hardware. This substitution reduces hardware complexity while improving measurement precision for LIDAR distance calculations.
2Measurement precision
If high-speed analog-to-digital converters are used to achieve high time resolution, then measurement precision is improved, but cost and power consumption increase
Solution Approach 1:
The patent employs standard-speed ADCs (operating at typical FPGA clock frequencies rather than gigasample rates) combined with temporal interpolation algorithms. The system uses multiple lower-cost, lower-power ADC samples taken at different time intervals to reconstruct high-resolution timing information. This approach replaces expensive high-speed ADCs with multiple inexpensive standard ADCs, reducing both cost and power consumption while achieving equivalent or superior time resolution.
Solution Approach 2:
The patent transitions from a single high-speed sampling dimension to multiple lower-speed sampling dimensions. Instead of one ADC operating at gigasample rates, the system uses multiple ADCs operating at standard rates but at different time offsets. The temporal dimension is expanded by taking multiple measurements at different phases, allowing reconstruction of high-resolution timing data through computational interpolation rather than hardware speed alone.
3Measurement precision
If traditional sampling methods with clock period resolution are used, then device complexity is reduced, but time resolution is insufficient for centimeter-level precision
Solution Approach 1:
The patent pre-generates multiple clock signals with different phase offsets before the actual measurement process. These phased clock signals are prepared in advance within the FPGA, creating a set of time-interleaved sampling windows. By having these clock phases ready beforehand, the system can interpolate timing measurements between clock edges without requiring complex real-time calculation, reducing operational complexity while achieving sub-clock-period time 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
This approach provides accurate, high-precision distance measurements with reduced costs and power consumption, suitable for complex and dynamic environments, such as obstacle detection and environmental mapping by autonomous or semi-autonomous vehicles.
Implementation Method 1
A returning light pulse reflected from the object is received at a light sensor
Implementation Method 2
a light sensor configured to receive a returning light pulse reflected from the object and output an analog pulse signal representing the returning light pulse
Implementation Method 3
The FPGA is configured to convert the analog pulse signal to a plurality of digital signal values, and generate a plurality of time measurements corresponding to the plurality of digital signal values by sampling each digital signal value
Data Source
AI summary
Systems and methods for performing optical distance measurement are provided. In one aspect, a system for measuring a distance to an object comprises a light emitter configured to emit an outbound light pulse, and a light sensor configured to receive a returning light pulse reflected from the object and output an analog pulse signal representing the returning light pulse. The system also comprises a field-programmable gate array (FPGA) coupled to the light sensor. The FPGA is configured to convert the analog pulse signal to a plurality of digital signal values, and generate a plurality of time measurements corresponding to the plurality of digital signal values. The system also comprises a controller configured to calculate the distance to the object based on the plurality of digital signal values and the plurality of time measurements.