Laser Distance Measuring Device Dynamic Selection
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Solution Overview
Problem
Existing laser scanning devices face challenges in accurately measuring distances under varying atmospheric conditions and interference from dust, humidity, and clouds, leading to difficulties in creating reliable landscape models and distinguishing between strong and weak reflections.
Innovation Solution
A laser scanning device with a selection device that adjusts the receiving surface based on the angular velocity of the beam deflection, allowing for selective suppression or emphasis of distance-related reflections, enabling better handling of interference and improving measurement accuracy by setting the distance measurement range dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed receiving surface is used for all measurements, then the device structure is simple, but it cannot suppress interfering reflections from dust, humidity or clouds at different distances
Solution Approach 1:
The receiving surface is made dynamically selectable through the selection device, which can switch between different receiving surfaces or active areas on the receiving surface based on the required measurement range. This dynamic configuration allows the system to adapt to different measurement scenarios (ground surveying vs. cloud measurement) and suppress interference from specific distance ranges while maintaining a relatively simple overall device structure.
2Measurement precision
If the laser receiver operates with maximum sensitivity to detect weak cloud reflections, then weak useful reflections can be detected, but strong ground reflections cause clipping or saturation
Solution Approach 1:
The selection device extracts or separates the useful signal from the interference by selectively directing only laser pulses from specific distance ranges to the laser receiver. When measuring clouds, it excludes strong ground reflections by making their corresponding receiving areas inactive, allowing the receiver to operate at maximum sensitivity without saturation from interfering reflections.
Solution Approach 2:
The selection device performs preliminary action by pre-configuring which receiving surfaces or areas are active before the laser pulses arrive. This preliminary configuration ensures that only reflections from the desired distance range (e.g., clouds) are directed to the receiver, preventing saturation from strong reflections (e.g., ground) before they even occur.
3Productivity
If a high pulse repetition rate is used to increase productivity, then more laser pulses can be sent, but the assignment of received pulses to transmission pulses becomes ambiguous due to multiple pulses in the air
Solution Approach 1:
The selection device performs preliminary action by pre-defining unambiguous assignment zones (MTA zones) for each transmitted pulse. By configuring the receiving surfaces and their active areas according to the pulse repetition rate and beam deflection characteristics, the system ensures that each receiving surface is only active during the time window when it should receive reflections from its corresponding transmission pulse, preventing ambiguity even at high pulse repetition rates.
4Adaptability or versatility
If the distance measurement range is fixed, then the device is simple to operate, but it cannot adapt to changing atmospheric conditions or flight altitude
Solution Approach 1:
The selection device enables dynamic adaptation to changing environmental conditions by automatically or manually switching between different receiving surfaces and measurement ranges based on factors such as flight altitude, atmospheric conditions, and terrain characteristics. This dynamic capability allows the system to maintain optimal performance across varying operational scenarios without requiring complex manual reconfiguration.
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
Enhances measurement accuracy by reducing interference, allowing operation under poorer weather conditions, increasing sensitivity, and enabling longer target distances to be measured without saturation, while minimizing mutual interference between devices.
Implementation Method 1
measuring the propagation time of laser pulses reflected thereon
Implementation Method 2
a beam deflector downstream of the laser transmitter and upstream of the laser receiver for deflecting the transmit and receive laser beams at a known angular velocity
Data Source
AI summary
A device (1) for measuring the distance to a target (Un) comprises a laser transmitter (6) for emitting a laser pulse (Sn) at a transmission time (TS,n) in the form of a transmitting laser beam (2), a laser receiver (12) for receiving the laser pulse (En) reflected at the target (Un) at a reception time (TE,n) in the form of a receiving laser beam (4) on a receiving surface (11) of the laser receiver (12), a beam deflection device (8) arranged downstream of the laser transmitter (6) and upstream of the laser receiver (12), which deflects the transmitting and receiving laser beams (2, 4) with a known angular velocity (W), and an evaluation device (13) connected to the laser transmitter (6) and the laser receiver (12) for measuring the time of flight (ΔTn) between the transmission and reception times (tS,n, tE,n) and from this the distance (Dn). of the target (Un), and a selection body (16) that is trained to do so,to select the receiving area (11) of the laser receiver (12) used for the measurement depending on the angular velocity (W) and a predetermined range (Gi) of measurable distances (Dn).