Laser Distance Sensor Adaptive Coincidence Control
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Solution Overview
Problem
Laser measuring apparatuses face challenges in accurately measuring distances at high speeds and long ranges due to interference from background light, which can lead to false measurements and reduced accuracy.
Innovation Solution
The apparatus employs a pulse laser, photon detection units, an evaluation device for generating coincidence signals, and a control device that adjusts the coincidence time and maximum event number based on background radiation levels, allowing for adaptive coincidence detection and improved signal-to-background ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensitivity of the sensor is lowered to reduce background events, then the rate of false measurements is reduced, but the probability of detecting the reflected laser pulse decreases
Solution Approach 1:
The sensor sensitivity is dynamically adjusted based on the detected background light intensity. The control unit modifies the sensor's sensitivity parameter in real-time to optimize the balance between reducing false measurements from background events and maintaining sufficient detection probability for the reflected laser pulse. This dynamic adaptation allows the system to respond to varying environmental conditions.
Solution Approach 2:
The invention changes the operational parameters of the sensor by adjusting its sensitivity level. By modifying the sensor's sensitivity parameter according to measured background radiation levels, the system optimizes the detection threshold to distinguish between background events and actual laser pulse reflections, thereby resolving the contradiction between false measurement reduction and detection probability.
2Length of stationary object
If the measurement range is extended to longer distances, then the coverage area increases, but the measurement accuracy decreases due to increased background light interference
Solution Approach 1:
The sensor sensitivity is dynamically adapted based on the measurement distance and background light conditions. For longer distances where background interference is more significant, the control unit adjusts the sensitivity parameter to optimize the signal-to-noise ratio, thereby maintaining measurement accuracy across extended ranges.
Solution Approach 2:
The system employs feedback mechanisms where the control unit continuously monitors background light intensity and measurement results. Based on this feedback, the sensitivity parameter is automatically adjusted to compensate for increased background interference at longer distances, ensuring consistent measurement accuracy across the full measurement range.
3Productivity
If the measurement speed is increased for high-speed applications, then the productivity improves, but the measurement accuracy deteriorates due to reduced integration time
Solution Approach 1:
The sensor sensitivity parameter is dynamically adjusted based on the measurement cycle duration. For high-speed measurements with shorter integration times, the control unit increases the sensitivity to compensate for the reduced time available for photon accumulation, thereby maintaining measurement accuracy while achieving high productivity.
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 enhances the dynamic range and accuracy of distance measurements by reducing the impact of background light, enabling reliable measurements at higher background intensities and longer ranges without compromising speed or accuracy.
Implementation Method 1
the propagation time of a laser pulse emitted by an active radiation source and reflected by a target object is measured
Implementation Method 2
a photon detection device with a group of detection units for detecting photons and for generating detection signals
Implementation Method 3
a time measuring device for measuring time periods from emitting one of the laser pulses to outputting one of the coincidence signals
Data Source
AI summary
A laser measuring apparatus for measuring distances is disclosed, including a pulse laser; a photon detection device with a group of detection units; an evaluation device; a time measuring device; and a control device, wherein the control device is configured such that a plurality of measurement cycles is performed during each of the measurement operations; that one of the laser pulses is emitted with the pulse laser at the beginning of each measurement cycle of the plurality of measurement cycles; that, by means of the time measuring device, during each measurement cycle, one of the time periods is measured for each of the coincidence signals being detected during the respective measurement cycle; that the time periods measured during several of the measurement cycles of one of the measurement operations by means of the time measuring device are used to generate the measurement value of the respective measurement operation; that an adjustment of a maximum value for an event number takes place that corresponds to the number of time periods that are used during one of the measurement cycles to generate the measurement value of the respective measurement operation, wherein several of the time periods measured previously by means of the time measuring device are used for the adjustment; and that after the adjustment of the maximum value, the coincidence time is adjusted in dependence on the maximum value and a measurement value of a background radiation determined by the control device.