ToF Multipath Detection via Variable Pulse Timing
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Solution Overview
Problem
Existing Time of Flight (ToF) camera systems face measurement accuracy degradation due to increased measurement errors in multipath environments, where directly reflected and indirectly reflected light are mixed, and are hindered by high costs and heavy processing loads for multipath detection.
Innovation Solution
A distance information acquisition device and multipath detection method that employs a light emitter and solid-state imaging element, with an emission/exposure controller generating timing signals for pairs of emission and exposure pulses with varying time differences, allowing for comparison with reference data to determine the presence of multipath and reduce processing load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a special dedicated lighting unit is used to reduce multipath effects, then measurement accuracy is improved, but device cost increases
Solution Approach 1:
The patent creates a virtual copy of the multipath detection function by processing existing ToF data through correlation analysis with reference profiles, eliminating the need for dedicated hardware lighting units while maintaining multipath detection capability
Solution Approach 2:
The existing ToF camera system is made multi-functional by enabling it to perform both distance measurement and multipath detection using the same hardware components, thereby avoiding additional device costs while improving measurement accuracy
2Measurement precision
If complex multipath detection algorithms are used, then measurement accuracy is improved, but processing load increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating reference profiles of received light signals for different distances and storing them in advance, so that during actual measurement only simple correlation comparison is needed, significantly reducing real-time processing load while maintaining accuracy
Solution Approach 2:
The patent replaces complex computational multipath detection algorithms with a simpler correlation-based comparison mechanism that uses pre-stored reference data, reducing processing requirements while achieving the same measurement accuracy improvement
3Productivity
If high throughput calculating machine is used for multipath detection, then real-time processing is achieved, but device compactness is reduced
Solution Approach 1:
By pre-calculating and storing reference profiles in memory, the system eliminates the need for high-throughput external computing machines during actual operation, allowing real-time processing to be achieved within the compact ToF camera device itself
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 lessens processing load and reduces costs while maintaining accurate distance measurements by effectively detecting multipath and correcting for errors in multipath environments.
Implementation Method 1
measures a distance using the time of flight (ToF) method
Implementation Method 2
a light emitter which emits light according to an emission pulse indicating emission
Implementation Method 3
a solid-state imaging element which performs exposure according to an exposure pulse indicating exposure
Implementation Method 4
in a multipath environment in which directly reflected light and indirectly reflected light are mixed
Data Source
AI summary
A distance information acquisition device includes: a light emitter which emits light according to an emission pulse indicating emission; a solid-state imaging element which performs exposure according to an exposure pulse indicating exposure; an emission/exposure controller which generates a timing signal indicating a plurality of pairs of the emission pulse and the exposure pulse having a time difference that is different in each of the plurality of pairs; and a multipath detector which obtains a sequence of received light signals from the solid-state imaging element by the emission and the exposure that correspond to each of the plurality of pairs, compares the obtained sequence of received light signals and reference data created in advance as a model of a sequence of received light signals in a multipath-free environment, and determines the presence or absence of multipath according to a difference in a comparison result.