Time of Flight Distance Measurement Using Segmented Exposure
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Solution Overview
Problem
The Time of Flight (TOF) method for distance measurement requires longer measurement times due to the need for stronger light pulses and multiple emission-exposure pairs, especially for distant targets, which increases the measurement time and reduces efficiency.
Innovation Solution
A distance measuring device that sets different measurement time ranges with varying conditions, including light pulse intensity and exposure segments, to calculate distance based on the time of light emission and reception, allowing for efficient distance measurement by reducing the number of emission-exposure pairs required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the measurement range is set to be wider to measure distant objects, then the measurement capability is improved, but the measurement time is lengthened
Solution Approach 1:
The patent divides the measurement time range into multiple segments (first measurement time range and second measurement time range) corresponding to different distance ranges. By segmenting the measurement process, the system can efficiently cover a wide measurement range without requiring excessively long measurement times for each segment, thus resolving the contradiction between wide measurement range and long measurement time.
Solution Approach 2:
The patent employs periodic light emission and exposure cycles with different delay amounts to measure distances at multiple time points. This periodic action allows the system to gather distance information across a wide range efficiently by repeating measurements at optimized intervals, reducing the total measurement time while maintaining wide adaptability.
2Measurement precision
If stronger light pulses are used to measure distant targets, then the detection capability is improved, but the measurement time is lengthened due to waiting time for synchronization
Solution Approach 1:
The patent pre-calculates and sets multiple delay amounts in advance before measurement begins. These delay amounts correspond to different expected distance ranges and are prepared beforehand, allowing the system to immediately use the appropriate delay setting when measuring distant targets without requiring waiting time for synchronization calculations during measurement, thus improving detection capability while reducing measurement time.
3Measurement precision
If multiple pairs of light emission and exposure are executed for high distance resolution, then the measurement precision is improved, but the measurement time is lengthened
Solution Approach 1:
The patent segments the measurement process into different time ranges with different delay amounts, where each segment is optimized for specific distance resolutions. By dividing the measurement into manageable segments rather than requiring all measurements to achieve maximum resolution simultaneously, the system achieves high distance resolution in critical areas while reducing total measurement time.
Solution Approach 2:
The patent changes measurement parameters (delay amounts, exposure timings) based on the specific measurement requirements for different distance ranges. By adapting parameters to match the measurement needs of each segment, the system achieves high distance resolution where necessary while avoiding unnecessary measurements that would increase time consumption, thus resolving the contradiction between precision and time.
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 enables efficient distance measurement by reducing measurement time and improving resolution, even for distant targets, by optimizing light emission and exposure conditions.
Implementation Method 1
a time of flight (TOF) method for measuring time required from when light is emitted from the distance measuring device toward a measurement target to when the light is reflected by the object and returns back to the distance measuring device
Data Source
AI summary
A distance measuring device includes a controller and a distance calculator. The controller sets, in a first time period, a first measurement time range corresponding to a first measurement distance range; causes a light emitter to emit light and places a light receiver into an exposure state, in the first measurement time range; sets, in a second time period, a second measurement time range corresponding to a second measurement distance range; and causes the light emitter to emit light and places the light receiver into an exposure state, in the second measurement time range. At least one measurement condition is different between the first and second time periods. The distance calculator calculates the distance from the distance measuring device to a measurement target, based on the time from the emission to the reflection of light. The time is in at least one of the first and second time periods.