Time-of-Flight Sensing System Multipath Error Correction
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Solution Overview
Problem
Conventional time-of-flight systems in navigation face challenges with multipath effects, low irradiance, and reduced signal-to-noise ratio due to the need to illuminate the entire scene, which limits their effectiveness in indoor and outdoor navigation applications.
Innovation Solution
A time-of-flight sensing system that emits a signal beam with a minor dimension and samples the reflected light with a field of view larger than the beam, allowing for the detection of both bright and dark regions, enabling the system to correct for multipath errors, identify transparent objects, and increase signal strength by concentrating the photon budget into a narrow beam or sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the entire scene is illuminated to enable comprehensive navigation sensing, then the coverage area is improved, but the signal-to-noise ratio deteriorates due to multipath effects and low irradiance
Solution Approach 1:
The patent divides the illumination task into multiple discrete light sources arranged in an array, where each light source illuminates a specific sector or region. This segmentation allows the system to cover a wide area while maintaining high irradiance in each individual sector, thereby improving signal-to-noise ratio while preserving comprehensive coverage.
Solution Approach 2:
The patent implements local quality by directing concentrated light beams from multiple light sources to different spatial sectors, creating regions of high irradiance where needed. This approach ensures that each local region receives sufficient photon flux for accurate time-of-flight measurements, while the overall system maintains wide coverage through the coordinated arrangement of multiple sources.
2Measurement precision
If a narrow beam is used to concentrate photon budget and improve signal strength, then the signal-to-noise ratio is improved, but the coverage area is reduced
Solution Approach 1:
The patent merges the output of multiple light sources, each producing a narrow high-intensity beam, into a coordinated illumination pattern. By combining these individual beams in space, the system achieves both the concentrated photon flux needed for high signal-to-noise ratio and the extended coverage area, as each beam covers a specific sector while collectively they illuminate the entire scene.
Solution Approach 2:
The patent transitions from a single-point illumination approach to a multi-dimensional array of light sources. By distributing light sources across multiple spatial dimensions and coordinating their beam directions, the system achieves wide angular coverage while maintaining narrow beam characteristics for high irradiance, effectively adding spatial dimensionality to resolve the contradiction.
3Area of stationary object
If multiple light sources are used to increase coverage, then the coverage area is improved, but the device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing each light source in the array to serve multiple purposes: illumination for time-of-flight sensing, spatial positioning through controlled beam direction, and collaborative coverage with adjacent sources. This universal design reduces overall system complexity compared to using specialized components for each function, as the same hardware structure performs multiple roles.
Solution Approach 2:
The patent introduces dynamic control of the light source array, where individual light sources can be selectively activated or deactivated based on navigation requirements. This dynamic operation allows the system to adjust coverage area and complexity in real-time, reducing device complexity by only activating the minimum necessary subset of light sources for any given sensing task while maintaining the capability for comprehensive coverage when needed.
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
The system improves detection sensitivity and resolution by minimizing multipath effects, enhancing the signal-to-noise ratio, and allowing for in-situ calibration, thereby improving navigation accuracy and obstacle avoidance capabilities.
Implementation Method 1
an emitter configured to emit a modulated light beam
Implementation Method 2
a detection system configured to record a reflected beam... determining object parameters including object distance from the sensed beam time of flight
Implementation Method 3
the beam or sheet having a minor dimension; sampling the reflected light beam
Data Source
AI summary
A sensing method, including: emitting a signal beam; sampling the reflected signal at a sensor with a field of view larger than the signal beam; and determining a surface parameter based on the bright and dark regions associated with the sampled signal.