Underground Line Locator with RTK GNSS Antenna Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing underground line location systems using GNSS suffer from inaccuracies due to the deployment of the GNSS antenna, which can be obstructed by the user, leading to errors in precise positioning and mapping of underground utilities.
Innovation Solution
A precise line locator system incorporating a wand with an array of low-frequency antennas and a Real-Time Kinematic (RTK) GNSS antenna, where the RTK GNSS antenna is positioned to maintain a clear view of the sky and corrected using inertial measurement units and magnetic declination data to align with the electromagnetic locate axis, ensuring accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the GNSS antenna is integrated into the handheld locator device, then the system portability and integration are improved, but the antenna view of the sky is obstructed by the user's hand and body, leading to positioning accuracy degradation
Solution Approach 1:
The patent transitions from 2D planar antenna arrays to 3D volumetric sensor distributions. Multiple GNSS antennas are positioned at different heights and angles on the handheld device, creating a three-dimensional antenna configuration that captures satellite signals from multiple spatial dimensions, thereby maintaining sky view despite hand obstruction
Solution Approach 2:
The GNSS receiving system is divided into multiple independent antenna elements distributed across the device structure. Each antenna segment independently receives signals from different satellite constellations, and their outputs are combined through signal processing to achieve accurate positioning without requiring a single unobstructed antenna view
2Ease of operation
If the locator device is held in various ergonomic orientations for comfortable operation, then the ease of operation is improved, but the alignment between the GNSS antenna and electromagnetic locate axis varies, causing positioning errors
Solution Approach 1:
The system dynamically adapts to changing device orientations through real-time sensor fusion. Inertial measurement units (IMUs) continuously track the device's pitch, roll, and yaw angles, and the processing system dynamically adjusts coordinate transformations and antenna phase center corrections based on the current ergonomic orientation, maintaining positioning accuracy regardless of how the user holds the device
Solution Approach 2:
The system incorporates feedback from inertial sensors and magnetic field sensors to continuously monitor device orientation. This orientation information is fed back to the positioning algorithm, which compensates for misalignment between the GNSS antenna and electromagnetic locate axis by applying rotation matrices and transformation corrections based on the measured device attitude
3Difficulty of detecting and measuring
If magnetic field sensors are used to detect underground utility signals, then the detection capability is improved, but the Earth's magnetic field and local magnetic interference cause measurement errors
Solution Approach 1:
The patent introduces magnetometer sensors as intermediary devices that measure the Earth's magnetic field vector. These magnetometers serve as reference sensors that detect ambient magnetic conditions, and their measurements are used to compensate for magnetic interference in the utility detection signals by establishing a baseline magnetic environment and correcting deviations caused by local magnetic anomalies
Solution Approach 2:
The system replaces reliance on single-frequency magnetic field detection with a multi-sensor fusion approach incorporating GNSS, inertial sensors, and magnetometers. This substitution of pure magnetic detection with a combined navigation system reduces vulnerability to magnetic interference by using redundant measurement modalities that are not affected by magnetic field anomalies
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
Achieves precise geographic location of underground lines with centimeter-level accuracy by combining low-frequency magnetic field detection with RTK GNSS, correcting for ergonomic and magnetic interference issues, enabling reliable mapping of underground utilities.
Implementation Method 1
Line locating instruments typically include an array of spaced antennas that receive time-varying magnetic field signals generated by the underground utility itself
Implementation Method 2
a real-time kinematic (RTK) Global Navigation Satellite (GNSS) antenna attached to the housing
Data Source
AI summary
A precise line locator is presented that provides precise line location. The locator includes a housing; a wand attached to the housing, the wand including an array of low frequency antennas arranged along the wand, the array of low frequency antennas defining an electromagnetic locate axis of the line locator system; a real-time kinematic (RTK) Global Navigation Satellite (GNSS) antenna attached to the housing; a user interface positioned in the housing; and a processing circuit coupled to the array of low frequency antennas, the RTK GNSS antenna, and the user interface, wherein the underground line locator determines locate data of the underground line based on signals from the array of low frequency antennas and determines a precise position of the underground line locator from the RTK GNSS antenna.