Aperiodic Optical Distance Measurement for Interference Resistance
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Solution Overview
Problem
Existing optical distance measurement systems, particularly in driverless vehicle navigation, are susceptible to interference from periodic interference pulses, leading to incorrect measurements due to their inability to distinguish between measurement pulses and interference signals, which is unacceptable for safety reasons in autonomous driving.
Innovation Solution
The method involves emitting a large number of measurement pulses aperiodically, using a pulse generation unit and a detector to determine the transit time of the pulses, and employing aperiodic transmission to reduce susceptibility to interference, with a device design that includes a pulse deflection unit for emitting and receiving pulses at different angles to enhance robustness against interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If periodic pulse transmission is used for distance measurement, then the measurement process is simple and systematic, but the system becomes susceptible to interference from periodic interference pulses
Solution Approach 1:
The patent applies periodic action in reverse - it uses aperiodic (irregular) pulse transmission intervals to prevent synchronization with interference sources. By deliberately avoiding regular periodicity in the pulse transmission timing, the system prevents interference pulses from being consistently detected while maintaining measurement functionality.
2Device complexity
If the system cannot distinguish between measurement pulses and interference pulses, then the detection process is straightforward, but incorrect measurements occur due to inclusion of interference signals
Solution Approach 1:
The patent implements feedback through correlation processing, where received pulses are compared against expected measurement pulse patterns. The system uses the known aperiodic transmission timing as a reference to identify and validate genuine measurement pulse returns, filtering out interference pulses that do not match the expected pattern.
Solution Approach 2:
The patent changes the temporal parameter of pulse transmission from periodic to aperiodic intervals. This parameter change creates a unique time signature for each measurement pulse that can be recognized and validated, enabling the system to distinguish measurement pulses from interference pulses without adding complex hardware discrimination mechanisms.
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 significantly reduces the impact of interference pulses, providing more accurate distance measurements by ensuring that interference pulses are not incorrectly included in the measurement data, thereby enhancing the reliability of distance measurement systems in autonomous navigation.
Implementation Method 1
a detector detecting the measurement pulse reflected from the target to the detector
Implementation Method 2
the time-of-flight principle. A scanning sensor, preferably a LIDAR (abbreviation for 'Light detection and ranging') sensor, is usually used, which periodically emits pulses. From the determination of the propagation time of the pulses from the sensor to objects and back, the distance to these objects can be deduced using the speed of light.
Data Source
Figure 1
Figure 2
AI summary
In order to render methods and devices for optically measuring distances less prone to faults, the measuring pulses for measuring distances are emitted aperiodically.