TOF Sensor Target Tracking with On-Axis Camera
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Solution Overview
Problem
Current geodetic measuring devices face challenges in accurately tracking targets, especially when targets are moving or obscured, due to limitations in sensor size and line-of-sight interruptions, leading to uncertainties in target identification and measurement.
Innovation Solution
Integration of a Time-Of-Flight (TOF) sensor with ATR functionality, providing both range and amplitude data, and a combined On-Axis Camera (OAC) and ATR system for improved target identification and tracking, using NIR sensitivity and switchable filters for enhanced accuracy and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional ATR detector is used for target identification, then the device structure remains simple, but target tracking reliability deteriorates when targets are moving or obscured
Solution Approach 1:
The patent combines the OAC (On-Axis Camera) and ATR (Automatic Target Recognition) detector into a single integrated sensor unit. The OAC provides wide-field visual monitoring while the ATR detector specifically identifies and tracks prism targets. By merging these two detection functions into one sensor assembly with shared optics and processing, the system achieves more reliable target tracking without proportionally increasing device complexity.
Solution Approach 2:
The integrated sensor system serves multiple functions: the OAC captures broad scene imagery for situational awareness and target search, while the ATR detector performs specialized prism recognition and tracking. This multi-functional sensor assembly allows the measuring device to handle both static and dynamic target scenarios, as well as obscured targets, using a single unified system rather than separate dedicated sensors.
2Measurement precision
If the sensor size is limited, then the device remains compact, but measurement precision deteriorates due to line-of-sight interruptions
Solution Approach 1:
The sensor system is segmented into two specialized detectors: the OAC with its wide field of view for detecting targets across a broad area, and the ATR detector with optimized optics for precise prism target acquisition. This segmentation allows each sensor to excel at its specific function, with the OAC compensating for line-of-sight interruptions by providing alternative viewing angles and the ATR ensuring precise measurement when the target is acquired.
Solution Approach 2:
The OAC acts as an intermediary between the environment and the ATR detector. When the ATR detector experiences line-of-sight interruptions or loses target acquisition, the OAC continuously monitors the scene and can reacquire the target, serving as a backup and enhancement to the primary measurement system. This intermediary sensor maintains measurement precision without requiring a large increase in overall sensor area.
3Adaptability or versatility
If multiple targets are present in the scene, then surveying versatility is improved, but target identification difficulty increases
Solution Approach 1:
The ATR detector is specifically optimized with local quality for prism target detection, using wavelength filtering and pattern recognition tailored to identify prism reflectors. This specialized detection capability allows the system to distinguish prism targets from other objects in the scene. The OAC provides complementary wide-area coverage, and together they enable the system to handle multiple targets with different characteristics without confusion.
Solution Approach 2:
The ATR detector utilizes spectral filtering to detect the specific wavelength characteristics of prism targets, effectively using 'color' or wavelength differentiation to identify targets. By tuning the detector to respond to the specific optical properties of surveying prisms, the system can automatically distinguish targeted prisms from other objects in the scene, even when multiple targets are present, reducing identification difficulty.
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
The solution enables more reliable and accurate target identification and tracking, even in dynamic scenes with multiple targets, by utilizing TOF range data and image data for precise positioning and differentiation, reducing errors and increasing efficiency in surveying operations.
Implementation Method 1
a Time-Of-Flight (TOF) sensor (15), wherein the TOF sensor (15) is configured for providing pixel-related TOF data of at least part of the scene as a TOF image
Implementation Method 2
a distance measuring unit comprising an emitting unit (4) configured for emitting collimated measuring radiation
Implementation Method 3
a receiving unit (5) configured for detecting at least a part of the collimated measuring radiation reflected by the target
Data Source
Figure 1~2
Figure 3~5
AI summary
A measuring device (1) for acquiring a three-dimensional measuring point related to a target in a scene, the measuring device (1) comprises a distance measuring unit comprising an emitting unit configured for emitting collimated measuring radiation (T) and a receiving unit configured for detecting at least a part of the collimated measuring radiation reflected (R) by the target, a directing unit rotatable around an elevation axis and configured for directing the measuring radiation towards the scene, a capturing unit, wherein the capturing unit comprises an image sensor and is configured to capture at least a scene image of at least part of the scene, and a controlling and processing unit configured at least for aligning the directing unit. The distance measuring unit and the capturing unit are arranged in the directing unit and an optical axis of the capturing unit is coaxially aligned with an optical axis of the distance measuring unit. The image sensor is configured to provide the scene image by generating pixel-related image data. The measuring device (1) comprises a Time-Of-Flight (TOF) sensor, wherein the TOF sensor is configured to provide pixel-related TOF data of at least part of the scene as a TOF image, the pixel-related TOF data comprises at least range data and/or amplitude data for each pixel of the TOF image. The controlling and processing unit comprises a target tracking functionality which is configured to continuously update target information by continuously updating the scene image and continuously deriving a position of the target in the scene image by image processing of the scene image and continuously deriving TOF data for the target by means of the TOF sensor. The target tracking functionality is configured to continuously control directing of the measuring radiation towards the target based on the updated target information.