Terrain Surveillance via Laser Time-of-Flight
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current surveillance systems for detecting unauthorized intrusions over long distances or rough terrain suffer from high false alarm rates, limited accuracy, significant power consumption, and high capital expenses, making them impractical for widespread deployment.
Innovation Solution
The system employs a curtain array of light beams projected onto the terrain, with a detection array measuring the time of flight of reflections to determine the distance and height of objects, allowing for accurate intrusion detection and terrain mapping, while minimizing false alarms and reducing system size and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If video camera imaging systems are used for intrusion detection, then the system can provide visual monitoring capability, but the false alarm rate increases and power consumption becomes significant
Solution Approach 1:
The patent replaces video camera imaging systems with a laser-based time-of-flight measurement system. Instead of using cameras that capture continuous visual images requiring significant processing power and energy, the invention uses laser beams projected onto the terrain with detectors measuring the time for light to travel to and from objects. This substitution of optical measurement methodology dramatically reduces false alarms by directly measuring position rather than analyzing video frames, and reduces power consumption by eliminating continuous video capture and processing.
2Measurement precision
If the distance between laser array and detector array is increased to improve measurement accuracy, then the location measurement accuracy improves, but the physical size of the instrument increases and installation becomes cumbersome
Solution Approach 1:
The patent resolves the contradiction between baseline distance and device size by transitioning from a two-dimensional planar separation to a three-dimensional spatial arrangement. The laser array and detector array are positioned at different heights (vertical separation) rather than being widely spaced horizontally. This vertical dimension allows for adequate baseline distance for accurate triangulation while keeping the horizontal footprint compact, making the instrument easier to install and less detectable by intruders.
3Area of stationary object
If video surveillance systems are deployed for long-distance border monitoring, then the coverage area increases, but the system cost and complexity increase significantly
Solution Approach 1:
The patent divides the surveillance function into discrete, independent laser beams that can be individually directed at specific sectors of the terrain. Rather than using a single complex video surveillance system to cover the entire area, multiple simple laser-range-finding units can be deployed, each covering a specific angular sector. This segmentation allows for scalable coverage - adding more units extends coverage without proportionally increasing the complexity of each individual unit, making long-distance border monitoring more cost-effective.
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 provides a cost-effective, high-sensitivity surveillance system with a low false alarm rate, capable of accurately detecting intrusions and mapping terrain, even over long distances, with improved accuracy and reduced physical size and power usage.
Implementation Method 1
detecting reflections from an array of individually distinguished light beams directed in predetermined direction into the field of view
Implementation Method 2
The systems described herewithin utilize the times of flight of the laser beams, from transmission to detection, in order to characterize the form of the terrain being surveilled
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~4C
AI summary
A system for the surveillance of terrain and the detection of intrusions over a plane extending into that terrain. A curtain array of light beams is projected along the plane and reflections from the terrain are detected by a sensor array essentially spatially coincident with the array of light sources. The times of flight of the beams are determined, and these characterize the form of the terrain being surveilled. The initial background reflection pattern is acquired and stored by the system. A sudden change in this detected background pattern can be defined as arising from an unexpected reflection, indicative of an intrusion. Signal processing systems are described utilizing modulated laser beams and detection at a frequency at least twice that of the modulation, such that reflected signals arising from the ON and the OFF periods of the laser modulation can be subtracted to eliminate the background signals.