Laser Scanner Multi-Pulse Histogram Distance Measurement
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Solution Overview
Problem
Current laser scanners face challenges in achieving high angular resolution and efficient energy utilization for distance measurement, particularly in safety applications, where they require high transmission power and sensitive receivers, leading to increased costs and limited dynamic range.
Innovation Solution
The implementation of a multi-pulse method using histogram memories to collect and evaluate received signals, allowing for improved energy utilization and increased angular resolution without altering the scanning frequency or pulse repetition rate, enabling more precise and robust distance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If pulse propagation method is used with high transmission power, then measurement range is improved, but receiver sensitivity and manufacturing costs increase
Solution Approach 1:
The patent applies periodic pulsed action by transmitting multiple light pulses at defined repetition rates and evaluating them in time windows. This periodic transmission allows distance measurement through time-of-flight calculation while using lower individual pulse energies, avoiding the need for high-power receivers.
Solution Approach 2:
The patent implements continuous scanning by overlapping time windows for multiple pulses and maintaining continuous histogram evaluation. This ensures that measurement is continuous without gaps, achieving both extended range and reduced cost by avoiding high-power components.
2Power
If phase-based method with continuous wave laser is used, then transmission power is reduced, but measurement precision and dynamic range are limited
Solution Approach 1:
The patent uses periodic pulsed transmission instead of continuous wave modulation. By transmitting discrete pulses and measuring their return time, the system achieves high precision distance measurement with low average power consumption, resolving the contradiction between power reduction and precision maintenance.
Solution Approach 2:
The patent dynamically adjusts the evaluation by using multiple pulses per angular position and overlapping time windows. This dynamic multi-pulse evaluation enhances measurement precision while keeping transmission power low, overcoming the limitations of simple phase-based methods.
3Measurement precision
If multiple pulses are transmitted per angular position, then signal-to-noise ratio is improved, but measurement time increases
Solution Approach 1:
The patent performs preliminary action by pre-defining multiple time windows for pulse evaluation and preparing histogram structures in advance. This allows rapid processing of multiple pulses without sequential delay, improving signal-to-noise ratio while minimizing measurement time through parallel evaluation preparation.
Solution Approach 2:
The patent maintains continuous useful action by overlapping time windows for multiple pulses and continuously updating histograms. This ensures that evaluation of subsequent pulses begins before previous pulses are fully processed, eliminating idle time and achieving high signal-to-noise ratio without proportional time increase.
4Measurement precision
If scanning frequency is increased to improve angular resolution, then angular resolution is improved, but energy utilization decreases
Solution Approach 1:
The patent segments the measurement process by transmitting multiple pulses at each angular position rather than scanning continuously at high speed. This segmentation allows accumulation of signal energy at each position, improving angular resolution while reducing overall energy consumption by avoiding high-speed scanning requirements.
Solution Approach 2:
The patent uses periodic pulse transmission at defined repetition rates, allowing multiple measurements per angular position. This periodic approach enables high angular resolution through signal accumulation without requiring increased scanning frequency, thereby maintaining efficient energy utilization.
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 signal-to-noise ratio, allows for quasi-continuous scanning, and reduces manufacturing costs, providing a cost-effective solution with improved angular resolution and range, while maintaining real-time evaluation capabilities.
Implementation Method 1
the laser scanner measures object spacings by means of the propagation time between the transmission and reception of an individual light pulse for pulse-based methods or pulse propagation methods
Implementation Method 2
a light beam generated by a laser periodically covers a monitoring zone with the aid of a deflection unit
Implementation Method 3
The light is remitted at objects in the monitoring zone and evaluated in the laser scanner
Data Source
AI summary
A laser scanner (10) detects and determines distances of objects comprises a light transmitter transmitting light in a plurality of consecutive individual pulses. A rotatable deflection unit (18) for the periodical deflection of the transmission light beam (16) into the monitoring zone (20) and an angular measurement unit (30) generates angular position signals (62) in dependence on an angular position of the deflection unit (18). An evaluation unit (32) identifies a received pulse associated with an object from a histogram (110) taken from a histogram memory (32a, 32b) to determine the distance of the object by means of a light propagation method. The histogram (110) is collected over a time interval which is associated with the angular position signal (62). In this connection at least two histogram memories (32a, 32b) are provided in order to collect a first histogram and a second histogram in overlapping time intervals.