Time-of-Flight Distance Measurement Using Dual Light Emissions
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Solution Overview
Problem
Conventional Time-of-Flight (ToF) measurement systems face challenges with high power consumption and large storage requirements due to the need for accurate distance measurement, particularly in direct mode systems using high-energy pulses and indirect mode systems requiring high modulation frequencies.
Innovation Solution
The proposed system employs a dual light emission approach, where a first light emission provides initial distance estimation, and a second emission with reduced power and frequency is used to generate a histogram for precise distance calculation, discarding unnecessary data to conserve memory and power, and utilizing a Pseudo-Random Bit Sequence to optimize light emissions and echo processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-energy pulses are used in direct mode ToF systems to achieve accurate distance measurement, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent divides the measurement process into multiple phases: a first light emission for initial distance estimation, followed by a second light emission for refined measurement. This segmentation allows the system to use high energy only when necessary for initial acquisition, then switch to lower energy modes for subsequent measurements, reducing overall power consumption while maintaining accuracy.
Solution Approach 2:
The system performs a preliminary distance estimation using the first light emission before conducting the main measurement with the second light emission. This preliminary action provides advance information that allows the system to optimize subsequent measurement parameters, enabling more efficient use of energy by avoiding unnecessary high-energy pulses.
2Measurement precision
If measurement data is retained in histogram memory for repeated measurements to achieve accurate results, then measurement precision is improved, but memory requirements increase
Solution Approach 1:
The patent extracts and utilizes distance information from the first echo to determine an estimated distance before processing the second echo. By extracting this preliminary information, the system can focus memory resources on storing only the necessary histogram data for the final accurate measurement, rather than retaining all raw data from multiple measurements.
Solution Approach 2:
The system performs preliminary processing of the first echo to extract distance information before the main measurement phase. This preliminary action reduces the burden on histogram memory by pre-processing and filtering data, so that only essential measurement data needs to be retained for the final accurate distance calculation.
3Measurement precision
If high modulation frequency is used in indirect mode ToF systems to achieve high precision, then measurement precision is improved, but power consumption and system complexity increase
Solution Approach 1:
The patent segments the measurement approach into two distinct light emissions with different purposes. The first emission provides coarse distance estimation, while the second emission performs the precise measurement. This segmentation allows the system to use lower modulation frequencies for the initial estimation, reducing complexity and power consumption, while reserving high-precision techniques only for the final measurement phase.
Solution Approach 2:
The system changes measurement parameters between the two light emissions. The first emission uses parameters optimized for快速获取粗略距离信息, while the second emission uses parameters optimized for precise measurement. This dynamic parameter adjustment allows the system to achieve high precision when needed while reducing complexity and power consumption during the initial acquisition phase.
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 consumption and memory requirements while maintaining accurate distance measurements, achieving efficient data storage and processing in both direct and indirect ToF systems.
Implementation Method 1
a first echo resulting from the first light emission being reflected by an object and a second echo resulting from the second light emission being reflected by the object
Implementation Method 2
This disclosure relates to measuring distance to an object using imaging sensors... Determining a distance between an imaging sensor and an object is vital in many uses of imaging sensors. One system created to determine a distance between an imaging sensor and an object is called a Time-of-Flight ('ToF') measurement system
Data Source
AI summary
The present disclosure describes a method and apparatus for enabling an imaging sensor to perform Time-of-Flight measurements while requiring less histogram memory and in many cases less power consumption. A light source is operated to cause multiple light emissions and a coarse/estimated distance is determined based on a first echo received based on the first light emission. A histogram is saved and a fine distance is calculated from the coarse distance and data derived from the echo of a second light emission.