Laser Tracker Tracking Method Using Capture Unit and Overview Device
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Solution Overview
Problem
Laser trackers face limitations in tracking moving target points due to delays in controlling the measuring beam direction, leading to interruptions in measurement and tracking, especially when the target moves rapidly or when obstacles obstruct the measuring beam, and existing systems struggle to maintain accurate position measurement during rapid angular changes or when the target is close to the tracker.
Innovation Solution
A tracking method and system with a laser tracker that incorporates a capture unit and an overview device with a larger detection range, allowing for automatic reacquisition of the target during interruptions and enabling tracking even with rapid changes in the target's angle, by switching between normal and extraordinary tracking modes based on detection by the tracking unit, capture unit, and overview device, and utilizing a zoom function and deflection device for precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measuring beam direction is controlled based on the parallel offset between emitted and reflected measuring beam, then the tracking accuracy is improved, but the response speed deteriorates due to delay
Solution Approach 1:
The patent applies preliminary action by using the overview device to detect the target point's position in advance before the measuring beam needs to be redirected. The system predicts where the target will be and pre-adjusts the measuring beam direction, eliminating the delay that occurs when waiting for offset detection and correction cycles to complete.
2Speed
If the measuring beam direction is changed rapidly to follow a moving target, then the tracking speed is improved, but the measurement precision deteriorates due to control delay
Solution Approach 1:
The overview device serves as an intermediary between the target point and the measuring beam control system. It provides advance positional information about the target, allowing the system to adjust the measuring beam direction proactively rather than reactively, maintaining both speed and precision during rapid target movements.
3Weight of moving object
If a small reflector is used on the target point, then the target portability is improved, but the detection reliability deteriorates when the target moves rapidly
Solution Approach 1:
The patent replaces the mechanical/optical limitation of relying solely on a small reflector with an electronic/image-based detection system. The overview device uses imaging technology to detect the target point's position, eliminating the need for a large physical reflector and enabling reliable tracking of lightweight, portable targets even during rapid movement.
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 system effectively bridges tracking interruptions and allows for dynamic tracking of moving targets with a larger opening angle, enabling continuous position measurement even during rapid angular changes, by using the capture unit and overview device to refine the target's alignment and maintain tracking without operator intervention.
Implementation Method 1
The target point to be measured is provided with a retroreflector (in particular a cube-corner prism or an arrangement of three mirrors standing perpendicular to one another), with the retroreflector reflecting the measuring beam of the laser tracker that hits it back to it.
Implementation Method 2
Part of the reflected measuring beam is usually directed to a PSD (position sensitive device). From the position in which the reflected measuring beam hits the light-sensitive surface of the PSD, the parallel displacement of the reflected relative to the emitted measuring beam is determined.
Data Source
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AI summary
A target (9) equipped with a reflector (17) can be tracked in a measuring system comprising a laser tracker (10). The reflector (17) is tracked by means of a tracking unit (11) in a normal tracking mode and by means of a surveying device (13) in an extraordinary tracking mode. A capturing unit (12) having a detection range lying between the detection ranges of the tracking unit (11) and of the surveying device (13) is also present. If the target (9) cannot be detected by the tracking unit (11) but can be detected by the capturing unit (12), the orientation of the tracking unit (11) is controlled according to a measurement by the capturing unit (12). If the target (9) can then be detected by the tracking unit (11), a transition to the normal tracking mode is initiated. If the target (9) can be detected only by the surveying device (13), the orientation of the tracking unit (11) is controlled according to a measurement of the surveying device (13).