Geodetic Instrument Image Sensor Axis Calibration
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Solution Overview
Problem
The assembly and positioning of geodetic instruments are time-consuming and require precise alignment of optical plummet elements with the instrument's vertical rotation axis, relying heavily on operator skill and calibration processes.
Innovation Solution
Incorporating an image capturing device, such as a CCD or CMOS sensor, to capture images of the ground and process them to determine the instrument's nadir point, allowing for calibration and mathematical displacement to align the instrument with desired coordinates without physical repositioning, and using reflecting elements for height determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical plummet elements are used for positioning the instrument, then the instrument can be positioned over a geodetically fixed reference point, but the assembly during manufacture requires time-consuming mounting and calibration to ensure accurate alignment of the sighting axis with the vertical rotation axis
Solution Approach 1:
The patent replaces the traditional mechanical optical plummet system with an electronic imaging system. A camera captures images of the ground, and image processing algorithms automatically determine the position of the vertical rotation axis. This substitution eliminates the need for precise mechanical mounting and manual calibration of optical elements, significantly reducing assembly time while maintaining positioning accuracy.
Solution Approach 2:
The patent creates a digital copy of the ground area beneath the instrument using a camera. Instead of directly observing the ground through optical plummet elements, the system captures an image and processes it to locate the nadir point. This copying approach allows for automated image processing to determine axis alignment, eliminating time-consuming manual alignment procedures.
2Measurement precision
If traditional optical plummet elements are used for positioning the instrument, then the instrument can be positioned over a geodetically fixed reference point, but the positioning during use is time consuming and relies entirely on operator skill
Solution Approach 1:
The system performs self-alignment through automated image processing. The camera captures the ground image, and the processing unit automatically identifies the nadir point and calculates the position of the vertical rotation axis without requiring operator intervention for alignment. The system serves itself by autonomously determining its position, eliminating dependence on operator skill for accurate positioning.
Solution Approach 2:
The manual mechanical alignment process is replaced with an automated electronic system. The camera and image processing unit automatically determine the instrument's position over the reference point, replacing the need for operators to manually align optical elements and make precise adjustments based on their skill and judgment.
3Ease of manufacture
If the image capturing device is not precisely aligned with the vertical rotation axis during assembly, then the assembly process is simplified, but the center point of the image sensor will not coincide with the vertical rotational axis requiring calibration
Solution Approach 1:
The system creates a digital representation of the ground and uses image processing to identify the relationship between the image center and the vertical rotation axis. By processing the captured image, the system calculates the offset between the image sensor center and the nadir point, allowing for mathematical compensation rather than requiring precise physical alignment during assembly.
Solution Approach 2:
The system changes from requiring precise physical alignment parameters to using mathematical offset parameters. Instead of demanding that the image sensor be perfectly centered on the vertical rotation axis during manufacturing, the system measures the actual offset and uses this parameter in calculations to achieve accurate positioning. This parameter transformation allows tolerance in manufacturing while maintaining precision in operation.
Data Source
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AI summary
A geodetic instrument is disclosed, wherein an image sensor is used for locating the instrument above a de- sired point on the ground. The positioning of the image sensor with respect to the instrument vertical rotation axis is determined, or calibrated, using a method where two images are captured at different horizontal rotational positions for the instrument, and where the center pixel of the image sensor is related to the vertical rotation axis by means of image processing. It is also disclosed how reflecting elements, such as prisms, may be used for providing stereoscopic vision that can be used for determining the instrument height above the ground.