GNSS Survey Pole Field Calibration for Misalignment
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Solution Overview
Problem
Survey systems with GNSS receivers mounted on survey poles face mechanical misalignment issues due to manufacturing tolerances and field damage, leading to reduced precision in data collection, with current solutions requiring replacement of poles or acceptance of errors.
Innovation Solution
A field calibration method using a calibration module on a data collector that processes GNSS and IMU data to determine mounting angles and correction factors, allowing for real-time adjustment of the GNSS receiver's attitude to improve accuracy, involving two sets of observations with the receiver facing different directions to account for pole misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical mounting methods (threaded connect, quick disconnect) are used to attach GNSS receiver to survey pole, then ease of assembly is improved, but manufacturing precision deteriorates due to mechanical misalignment
Solution Approach 1:
The patent applies preliminary action by performing calibration before actual surveying operations. The calibration process establishes correction factors in advance that compensate for mechanical misalignment, allowing the system to achieve high measurement precision despite the ease of mechanical assembly. The calibration is performed prior to data collection to pre-determine the relationship between the receiver coordinate system and the pole axis.
Solution Approach 2:
The patent changes the parameter approach by introducing correction factors (mounting angle, pole length, receiver offset) that are determined during calibration and then applied to all subsequent measurements. These parameter adjustments transform the raw measurements into corrected values, resolving the contradiction between easy mechanical assembly and precise alignment by mathematically compensating for the mechanical misalignment.
2Adaptability or versatility
If survey system is used with bent or damaged pole, then adaptability is improved, but measurement precision deteriorates due to misalignment
Solution Approach 1:
The patent applies feedback by implementing a calibration process that measures the actual misalignment caused by pole bending or damage and uses this information to generate correction factors. The calibration involves taking observations in multiple orientations and using the results to compute the mounting angle and other correction parameters, which are then fed back into the measurement system to compensate for the pole deformation.
Solution Approach 2:
The calibration is performed as a preliminary action before actual surveying begins. By determining the correction factors in advance through a dedicated calibration process, the system prepares compensation data that will be applied to all subsequent measurements, allowing the system to adapt to bent or damaged poles while maintaining measurement precision.
3Measurement precision
If field calibration is implemented, then measurement precision is improved, but device complexity increases due to additional calibration module and procedures
Solution Approach 1:
The calibration module is designed with multi-functionality, serving both as a calibration tool and as part of the normal surveying system. The same receiver and data collector used for surveying also perform the calibration functions, eliminating the need for separate dedicated calibration equipment. The calibration module integrates with the existing system architecture, using the same communication interfaces and processing capabilities.
Solution Approach 2:
The system performs self-calibration using its own internal resources. The calibration process utilizes the GNSS receiver's own observations and the data collector's processing capabilities to determine correction factors without requiring external calibration equipment. The system calibrates itself by taking observations in multiple orientations and computing the mounting angle parameters internally.
4Manufacturing precision
If calibration process is performed, then manufacturing precision is improved, but loss of time increases due to additional calibration steps
Solution Approach 1:
The patent applies partial action by performing calibration only when necessary - specifically when entering a new work area, after pole replacement or damage, or when misalignment is detected. Rather than requiring continuous calibration, the system performs calibration selectively based on operational conditions, reducing the overall time loss while maintaining precision when needed.
Solution Approach 2:
The calibration process determines correction factors (mounting angle, pole length, receiver offset) that are then applied to all measurements. By pre-calculating these parameters and storing them for use, the system avoids the need for complex real-time calculations during surveying operations, thereby reducing the time impact of calibration while maintaining high measurement precision.
Data Source
AI summary
A survey system configured to perform a calibration that eliminates, or at least significantly reduces, mechanical misalignment issues with the receiver or top unit (e.g., a GNSS receiver or the like), the mounting hardware, and the survey pole of the survey system. The survey system may include a data collector mounted upon the pole, and a calibration module (i.e., calibrating software and/or firmware) may be run or provided on the data collector or other component of the survey system (e.g., on the top unit). The calibration module processes data collected (including data from its inertial measurement unit (IMU)) by the top unit during calibration operations (or simply calibration) to determine a mounting angle and a correction factor (or corrections for attitude) based on this mounting angle, and the correction factor is communicated to the top unit for use in later data collection to improve accuracy of the survey system.