ToF Sensor Phase Delay Measurement Using Offset Signal Correlation
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Solution Overview
Problem
Conventional techniques for determining phase delay in time-of-flight sensors often result in inaccurate and suboptimal measurements, leading to unsafe vehicle behavior due to incorrect distance calculations.
Innovation Solution
A sensor management component uses linear equations to determine phase delay by cross-correlating emitted and received light signals at multiple offsets, calculating overlapping regions, and applying normalized amplitudes to map to specific linear equations, reducing computational complexity and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional techniques are used to determine phase delay, then the measurement process is simple, but the measurement precision deteriorates resulting in inaccurate distance calculations
Solution Approach 1:
The patent segments the determination of phase delay into multiple discrete steps: generating quadrature signals at different phase offsets, calculating correlation values for each offset, determining normalized amplitude values, and using these to solve for the phase delay. This segmentation transforms a complex direct measurement into manageable computational steps that improve accuracy while controlling complexity.
Solution Approach 2:
The patent performs preliminary actions by pre-generating quadrature signals at multiple known phase offsets before comparing them with the received signal. By preparing these reference signals in advance with known phase relationships, the system establishes a framework that simplifies the subsequent phase delay calculation and improves measurement precision through systematic comparison.
2Productivity
If conventional phase delay determination is used, then computational resources are consumed, but the productivity deteriorates due to slower processing speed
Solution Approach 1:
The patent extracts the essential phase delay information by comparing the received signal only with quadrature signals at specific phase offsets (0°, 90°, 180°, 270°) rather than performing exhaustive comparisons across all possible phase values. This extraction approach isolates the critical measurement points, reducing computational resource requirements while maintaining processing speed.
Solution Approach 2:
The patent changes the parameter approach by using normalized amplitude values derived from correlation calculations at discrete phase offsets as the basis for determining phase delay. Instead of directly measuring phase continuously, the system transforms the problem into calculating amplitudes at specific parameter points (phase offsets), which reduces computational complexity and improves processing efficiency.
Data Source
AI summary
Techniques for determining a phase delay of a received light signal are discussed herein. A vehicle may emit a continuous light signal from a ToF device. The ToF device may include a sensor receiver configured to receive the signal after the signal reflects off surface(s) in the environment. To determine the distance between the ToF device and the surface(s), the vehicle may sample the received signal at two or more offsets and identify regions of overlap between the offset signals and the received signal. The vehicle can determine area measurements of the overlapping regions and use such area measurements to determine normalized amplitudes for each of the overlapping regions and, based on comparing such values, determine linear equation(s) corresponding to the phase delay. The vehicle can evaluate such linear equations to determine the phase delay of the received light signal. The vehicle can be controlled based on the phase delay.