Submitted:
24 December 2025
Posted:
25 December 2025
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Abstract
Keywords:
1. Introduction
- Mean drift as the vector sum of platform motion and wind at release height, expressed in along-/cross-track coordinates tied to the current heading .
- Turbulence-driven spread via an Ornstein–Uhlenbeck process with a height-dependent Lagrangian time scale, yielding closed-form integrals for position variance over the fall.
- Operational error budget that incorporates release-timing jitter, small heading deviations, and wind-direction uncertainty so predictions reflect field realities.
- Physics-grounded model. A concise, reproducible formulation combining quadratic-drag fall time, a height-varying wind field, Ornstein–Uhlenbeck (OU) turbulence, and a calibrated operational error budget to explain accuracy across environments.
- Performance in visible metrics. To evaluate our environment formulation, we report several key performance parameters such as hit probability, center-proximity score, CEP50/CR95, and along-/cross-track error decomposition reveal how height, speed, and heading shape precision and recall.
- Practitioner-ready tooling. A lightweight, web-based dashboard renders KPIs, visual maps, and “what-if” analyses to guide operators toward height-speed-heading choices and flight paths that maximize recall for a given environment.
- Environment-aware optimizer. Given ambient conditions (10 m wind speed, wind-to direction, and turbulence intensity), the system recommends the drone’s height, speed and heading to maximize hit rate under throughput and safety constraints.
- These contributions deliver a reproducible and interpretable decision-support system for precision aerial seeding, integrating physics-based modeling, probabilistic reasoning, and real-time planning into a single operational tool.
2. Related Work
2.1. UAV Seeding in Forestry and Farming
2.2. Drop Accuracy Relevant Dispersion Models
2.3. Accuracy Metrics and Reporting
2.4. Summary and Gap
3. Physics-Based Model and Rationale
A. Vertical Descent Under Quadratic Drag (Summary; Calculation Introduced in A)
B. Mean Wind at Release Height
C. Mean Drift in the Heading Frame
D. Turbulence-Driven Spread (Summary; Full Derivation in Appendix C)
E. Operational error budget
F. Effective isotropic spread for a circular acceptance
G. Hit probability for a circular acceptance
Case 1 — Mean-centered (): with lead compensation
Case 2 — Mean-offset (): without lead compensation
| Symbol | Meaning | Units |
|---|---|---|
| H | Release height above ground | m |
| m | Seed/propagule mass | kg |
| A | Aerodynamic reference area (projected) | m2 |
| Quadratic drag coefficient | – | |
| Air density | kg m−3 | |
| g | Gravitational acceleration | m s−2 |
| Terminal speed (vertical) (3.2) | m s−1 | |
| Exact fall time (3.4) | s | |
| Wind speed at 10 m AGL | m s−1 | |
| Power-law shear exponent (3.5) | – | |
| Mean wind speed at height H (3.5) | m s−1 | |
| Mean wind vector at H | m s−1 | |
| Wind-to direction (azimuth) | rad or deg | |
| Vehicle heading (to) | rad or deg | |
| Relative angle | rad or deg | |
| Vehicle airspeed along heading | m s−1 | |
| k | Drag constant | m−1 |
| Heading and cross-heading unit vectors | – | |
| Along-/cross-track drift (3.9) | m | |
| Mean drift vector (3.10) | m | |
| d | Mean offset | m |
| I | Turbulence intensity | – |
| Turbulent stdevs (along/cross) | m s−1 | |
| Lagrangian timescale | s | |
| Timescale constant (2–5) | – | |
| Turbulent position spreads (OU) | m | |
| Release-time jitter stdev | s | |
| Heading jitter stdev | rad | |
| Wind-direction uncertainty stdev | rad | |
| Sensor/mechanical error floor (per axis) | m | |
| Total along/cross spreads (3.26)–(3.27) | m | |
| Effective isotropic spread (3.29) | m | |
| s | Cell side length | m |
| Acceptance radius | m | |
| Hit probability (Rayleigh/Rice) | – | |
| 50% circular error probable | m | |
| 95% containment radius | m |
4. From Model to Tool: Real-Time Seeding Planner (Dashboard & Package)
- Exposure time (Sec. 3 A).
- Mean wind at height via the power law (Sec. 3 B).
- Mean drift and in the heading frame (Sec. 3 C).
- Turbulence spread from OU finite-time dispersion (Sec. 3 D).
- Operational errors (timing, heading, wind-direction) mapped to meters (Sec. E), combined axis-wise to .
- Effective isotropic spread (Sec. 3 F).
- Hit probability for circular acceptance of radius r (Rayleigh for lead/, Rice/Marcum–Q for no-lead/, Sec. 3 G).
Example A (Excellent recall; dashboard: 98–99%)
Example B (low recall under tailwind alignment)
5 m (orange): lower release, best precision, minimal wind exposure;
10 m (green): nominal operating altitude;
15 m (red): higher release, more drift, degraded accuracy.
Low (2 m/s, green dashed)
Nominal (current speed, solid green)
High (8 m/s, red dashed)
Green: excellent seeding accuracy
Orange: acceptable or good performance
Red: degraded performance
5. Conclusion
| 1 | The assumption that is constant during the short fall time T, however, has been successfully used in modeling near surface dispersion semi-classically [13,25]. For typical release heights ( m), T is about one second, so any acceleration term contributes a second-order bias that is negligible relative to the modeled turbulent and operational spreads (Secs. 3–D,E). This approximation enables closed-form solutions without loss of predictive accuracy. |
| 2 |
is the total horizontal wind component along axis ; it is the wind actually observed at time t. The term denotes the random fluctuation about the mean. Accordingly, we decompose into a deterministic mean and a random fluctuation: . |
| 3 | We include a small, nonzero mechanical floor to prevent a zero-variance artifact when aerodynamic terms are small, keep the hit-probability model well-posed, and avoid forcing turbulence/jitter parameters to absorb hardware imperfections. |
Acknowledgments
Conflicts of Interest
Appendix A. Vertical Dynamics (Quadratic Drag) and Exact Fall Time
Appendix B. Mean Drift: Bearings, Components, and Refinements
Appendix C. Finite-Time OU Turbulence and Displacement Variance
Aim.
Why Ornstein–Uhlenbeck (OU)?
Model (per axis).
From velocity to displacement.
Parameters and units.
- (m s−1): zero-mean turbulent velocity in axis i.
- (m s−1): RMS gust speed in axis i.
- (s): Lagrangian integral time scale (memory of ).
- : Wiener process; .
- (m): turbulent displacement over T.
Near-surface parametrization (neutral)
Limits.
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