Optical Distance Measurement Using Segmented Pulse Intervals
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Solution Overview
Problem
Existing optical distance measurement methods, particularly for driverless vehicle navigation, face limitations due to aliasing effects and the inability to emit measurement pulses quickly enough, leading to incorrect object positioning and reduced measurement frequency.
Innovation Solution
The method involves emitting multiple measurement pulses with varying constant pulse intervals, allowing for closer timing between pulses while maintaining clear object positioning, using a time-of-flight principle with event-based histogram formation to accurately determine distances by accumulating possible object positions in a single histogram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If measurement pulses are transmitted quickly one after another, then measurement frequency is improved, but aliasing effects occur causing incorrect object positioning
Solution Approach 1:
The patent segments the measurement pulses into N subgroups, where each subgroup has a different constant pulse interval. This segmentation allows the system to transmit pulses more frequently overall while maintaining unambiguous distance measurement by using the unique pulse intervals of each subgroup to resolve aliasing effects.
Solution Approach 2:
The patent introduces an additional dimension by varying the pulse interval parameter across different subgroups. Instead of using a single pulse interval, the system uses multiple intervals (first, second, ..., Nth constant pulse intervals) to create a multi-dimensional measurement space where object positions can be uniquely identified even with high measurement frequencies.
2Productivity
If measurement pulses are transmitted at intervals less than twice the propagation time to maximum distance, then measurement frequency is improved, but clear assignment of reflected pulses becomes difficult
Solution Approach 1:
The patent divides the measurement pulses into N subgroups with different constant pulse intervals. This segmentation enables the system to transmit pulses at intervals shorter than twice the propagation time while still maintaining clear pulse assignment through the unique interval characteristics of each subgroup.
Solution Approach 2:
The patent changes the pulse interval parameter across different subgroups (first constant pulse interval, second constant pulse interval, ..., Nth constant pulse interval). By varying this critical parameter, the system can operate at higher measurement frequencies while preserving the ability to clearly assign reflected pulses to their corresponding transmitted pulses.
3Measurement precision
If waiting time of twice the propagation time is observed before emitting next pulse, then clear object position determination is maintained, but measurement frequency is severely limited
Solution Approach 1:
The patent segments pulses into multiple subgroups with different intervals, allowing the system to reduce the waiting time between pulses from twice the propagation time to intervals shorter than this duration, thereby increasing measurement frequency while maintaining position accuracy.
Solution Approach 2:
The patent employs periodic transmission of pulse subgroups with different constant intervals. This periodic action with varying intervals allows the system to maintain clear object position determination while operating at higher measurement frequencies by efficiently utilizing the time between pulse transmissions.
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 more frequent measurements, reduces ambiguity in object positioning, and increases measurement quality by preventing aliasing effects, allowing for accurate reconstruction of the actual object position within a reduced time frame.
Implementation Method 1
They are based on the time-of-flight principle, using a scanning sensor, particularly a LIDAR (short for 'Light Detection and Ranging') sensor, which periodically emits measurement pulses that are reflected by objects. The reflected measurement pulses are then detected. By determining the travel time of the measurement pulses from the sensor to the objects and back, the distance to these objects can be determined using the speed of light.
Implementation Method 2
The measurement pulses that are reflected by the objects are received. The measurement pulse reflected by the object is a measurement pulse which was previously transmitted, so its propagation direction has changed due to the reflection from the object.
Implementation Method 3
The invention discloses a method for optical distance measurement with several subgroups of measurement pulses. The measuring pulses are transmitted with different constant pulse intervals. By determining the travel time of the measurement pulses to the objects from which they were reflected and accumulating all possible object positions in a histogram, the actual object position can be clearly identified.
Data Source
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AI summary
A method (100) for optical distance measurement is proposed, comprising the emission (101) of a plurality of measurement pulses (13), the reflection (103) of emitted measurement pulses from at least one object (20) in a measurement range (17) of length (17a), and the reception (104) of reflected measurement pulses (13). N subgroups of measurement pulses (13) are emitted (102), each subgroup having a constant pulse spacing. The constant pulse spacing of different subgroups differs, with the least common multiple of the constant pulse spacings of the N subgroups being at least twice the length (17a) of the measurement range (17).