TOF Distance Sensing with Switched Emission Modes Against Interference
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Solution Overview
Problem
Interference among multiple TOF sensors mounted on vehicles for distance measurement in automatic driving systems leads to decreased accuracy and sensitivity, as proposed solutions like delaying pulse patterns or extending pulse widths increase non-emission times, reducing the total amount of received light.
Innovation Solution
A distance measuring device and method that switches between a first and second emission mode within a predetermined frame, controlling emission timing to minimize interference by varying the phase of emitted pulses, using a light emission controller and pattern switching mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the time to emit a pulse pattern of irradiation light is delayed by a time calculated by a pseudo-random number for each model, then interference among multiple TOF sensors is suppressed, but a non-emission time increases, so that the total amount of received light decreases and distance measurement sensitivity deteriorates
Solution Approach 1:
The patent applies periodic action by dividing the measurement frame into multiple subframes, where irradiation light is emitted in a pulse pattern within each subframe. This periodic emission structure allows multiple TOF sensors to operate simultaneously while maintaining distinct emission timing through pseudo-random delays, thereby suppressing interference without requiring complete non-emission periods that would reduce total received light
Solution Approach 2:
The patent segments the measurement frame into multiple subframes, with each subframe containing a pulse pattern of irradiation light. This segmentation allows the emission duty cycle to be distributed across multiple time segments, reducing the non-emission time within each subframe while maintaining overall interference suppression through the segmented structure combined with pseudo-random timing offsets
2Object-affected harmful factors
If the pulse width of irradiation light is extended by the time calculated by a pseudo-random number, then interference among multiple TOF sensors is suppressed, but a non-emission time increases, so that the total amount of received light decreases and distance measurement sensitivity deteriorates
Solution Approach 1:
The patent uses periodic action by emitting irradiation light in pulse patterns within subframes rather than extending continuous pulse widths. This periodic emission maintains high emission duty cycles within each subframe while using pseudo-random timing offsets between different sensors to suppress interference, avoiding the sensitivity deterioration caused by extended non-emission periods
Solution Approach 2:
The patent applies dynamics by making the emission timing flexible and adaptive through pseudo-random delays applied to the pulse pattern timing. This dynamic timing adjustment allows the system to suppress interference without fixed extended non-emission periods, maintaining higher total received light amounts compared to static pulse width extension methods
3Adaptability or versatility
If multiple TOF sensors are mounted on a vehicle to measure distance in each direction, then distance measurement coverage is improved, but interference occurs among the sensors, decreasing measurement accuracy
Solution Approach 1:
The patent segments the operation of multiple TOF sensors by assigning each sensor distinct pseudo-random timing offsets within the subframe structure. This segmentation allows all sensors to operate simultaneously across different directions (improving coverage) while their individually offset pulse patterns prevent mutual interference (maintaining accuracy)
Solution Approach 2:
The patent employs periodic action by organizing emissions from multiple sensors into synchronized subframe cycles with pseudo-random timing variations. This periodic structure enables coordinated operation of multiple sensors for comprehensive directional coverage while the timing offsets within each period prevent interference, maintaining measurement accuracy
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 maintains accurate distance measurement by reducing interference among multiple sensors, ensuring consistent light reception and enhancing sensitivity despite simultaneous operations.
Implementation Method 1
a light emitter that emits irradiation light
Implementation Method 2
reflected light resulting from reflection of the irradiation light on a target object
Implementation Method 3
a calculator that calculates a distance to the target object on the basis of a time from emission of the irradiation light to reception of the reflected light
Data Source
AI summary
Provided is a distance measuring device that includes a light emitter that emits irradiation light; a light receiver that receives reflected light resulting from reflection of the irradiation light on a target object, a calculator that calculates a distance to the target object on the basis of a time from emission of the irradiation light to reception of the reflected light, and a light emission controller that controls the light emitter. The light emission controller controls emission by the light emitter by switching a first emission mode and a second emission mode different from the first emission mode within a predetermined frame.