Slide 1 of 14
Slide 1 - 面向精密工程测量的 磁偏角快速测量算法
面向精密工程测量的 磁偏角快速测量算法
Chen Huizhen, Xu Caixu et al. Geospatial Information, Vol.24 No.3, Mar. 2026 DOI: 10.3969/j.issn.1672-4623.2026.03.026
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Rapid Magnetic Declination Measurement Algorithm for Precision Engineering
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利用我所给的论文，将该ppt进行优化，插图进行替换，专业知识讲解再具体点。
This presentation details a fast algorithm for measuring magnetic declination in precision engineering surveys, overcoming electronic compass inaccuracies from environmental interference. It covers problem challenges, geomagnetic theory, GNSS-IMU-compass fusion methodology with multi-scale estimation and least-squares correction, experimental setup in complex terrain, results showing stable declination (e.g., ±0.33° vs. WMM) and 0.03m coordinate precision, plus innovations for inertial navigation applications.
May 8, 202614 slides
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Slide 2 - Presentation Outline
- Problem Statement and Challenges
- Theoretical Foundations of Magnetic Declination
- Methodology: True North and Magnetic North Calculations
- Algorithm: Multi-Scale Fusion and Correction
- Experimental Setup and Data Collection
- Results: Magnetic Declination Stability
- Precision Verification: 0.03m Coordinate Accuracy
- Conclusion and Innovations
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Slide 3 - Problem Statement
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Problem Statement
Challenges in Electronic Compass Accuracy for Precision Engineering
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Slide 4 - Key Challenges
- Magnetic declination (D): Angle between magnetic north and true north, varies regionally due to environment and sensor factors
- Causes large fluctuations in true magnetic declination values
- Degrades electronic compass heading accuracy in inertial navigation
- Critical for precision engineering: aviation, surveying, mining, geophysics
- Requires rapid, site-specific correction to achieve sub-meter coordinate precision
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Slide 5 - Geomagnetic Field Model
- Magnetic field strength B: total magnitude
- Declination D: horizontal component angle from true north
- Inclination I: angle from horizontal plane
- Horizontal components: Bx (north), By (east)
- Models: IGRF, WMM updated every 5 years
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Slide 6 - Methodology
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Methodology
GNSS + Compass Fusion for Rapid Declination Measurement
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Slide 7 - Algorithm Workflow
| Step | Description |
|---|---|
| 1 | Preprocess GNSS/IMU data: geodetic to Gauss-Krüger plane coordinates (N,E,H) |
| 2 | Compute true north β = arctan((yb - ya)/(xb - xa)) from vectors |
| 3 | Attitude angles: γ=acos(accy / accz), θ=asin(acc_x) |
| 4 | Magnetic north: Hx = Mx cosγ + ... , Hy = My cosθ - Mz sinθ; Φ = arctan(Hy / Hx) |
| 5 | Sample at 45°,135°,225°,315°; check diff<3°, range≤3° |
| 6 | Least squares magnetic field correction; adaptive outlier rejection |
| 7 | Multi-scale fusion for precise declination D = Φ - β |
| 8 | Validate with WMM2020 model |
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Slide 8 - True North vs. Magnetic North Calculation
True North Azimuth (β) Gauss-Krüger plane coords A(xa,ya), B(xb,yb) β = arctan( (yb - ya) / (xb - xa) ) Vector angle from horizontal; minimizes projection error
Magnetic North Azimuth (Φ) Attitude: γ=acos(accy/accz), θ=asin(acc_x) Hx = Mx cosγ + My sinγ sinθ + Mz sinγ cosθ Hy = My cosθ - Mz sinθ Φ = arctan(Hy / Hx) Least squares correction for environment adaptability
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Slide 9 - Measured Declination Results (°)
| Direction | True North | Magnetic North | Declination |
|---|---|---|---|
| 45° | 41.559 | 45.322 | 3.762 |
| 135° | 135.745 | 136.944 | 1.199 |
| 225° | 223.140 | 225.818 | 2.678 |
| 315° | 309.770 | 312.890 | 3.120 |
Source: From paper Table 1
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Slide 11 - Magnetic Declination Stability
- 3.76°: 45° Avg
- 1.19°: 135° Avg
- 2.68°: 225° Avg
- 3.12°: 315° Avg
- ±0.33°: WMM Deviation
- 0.03m: Coord Precision
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Slide 12 of 14
Slide 12 - Azimuth and Declination Variation Curves
- True/magnetic north curves stable over time
- Declination variations averaged and fused
- Deviations corrected via least squares
- WMM model bias: up to 8° addressed by local fusion
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Slide 13 - Tilt Compensation Precision
- 0.03m: RMS Error
- <0.1m: Threshold
- 100 groups: Test Data
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Slide 14 - Conclusion
Algorithm achieves stable magnetic declination in any environment 0.03m coordinate correction precision via GNSS-compass fusion Innovations: Multi-scale estimation model, least squares correction, WMM validation High integration, simple operation, broad application in inertial navigation
Future: Optimize sampling efficiency, enhance anti-interference for harsh conditions
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