Tau Theory-Based Flare Control in Autonomous Helicopter Autorotation
Abstract
:1. Introduction
2. Simulation Model
Parameter | Value | Units |
---|---|---|
Mass and inertia | ||
Gross weight, W | 16,270 | lb |
Roll-axis moment of inertia, | 5000 | sl-ft2 |
Pitch-axis moment of inertia, | 39,000 | sl-ft2 |
Yaw-axis moment of inertia, | 39,000 | sl-ft2 |
Roll/yaw-axes product of inertia, | 1900 | sl-ft2 |
Main rotor | ||
Number of blades, | 4 | - |
Radius, R | ft | |
Blade chord, c | ft | |
Blade twist, | −13 | deg |
Flapping hinge offset | 1.25 | ft |
Blade weight, | 256.9 | lb |
Blade first mass moment, | 86.7 | sl-ft |
Blade second mass moment, | 1512.6 | sl-ft2 |
Angular speed, | 27 | rad/s |
Tail rotor | ||
Number of blades, | 4 | - |
Radius, | ft | |
Blade chord, | ft | |
Blade twist, | −17 | deg |
Blade second mass moment, | sl-ft | |
Angular speed, | rad/s |
3. Trajectory Generation
4. Autonomous Flare Control Law
4.1. Linear Models
4.2. Inner Loop
4.3. Outer Loop
4.4. Error Dynamics
5. Results
5.1. Demonstration of Autonomous Flare Control Law
5.2. Reachability Study
6. Conclusions
- Scheduling of the NDI control law with linearized models of the rotorcraft flight dynamics in steady-state autorotation has been shown to be a successful approach for tracking flare trajectories. In addition to achieving adequate tracking of the longitudinal and vertical trajectories, the control law also showed good performance in mitigating the off-axis response.
- State histories of the autonomous flare maneuvers largely mimic those of piloted flight simulations. Noticeable differences lie in a more aggressive longitudinal deceleration in the early stages of flare, and a delayed pitchover before landing.
- The proposed method was used to predict combinations of downrange distances and altitudes at flare entry that result in desired and marginal landings. These predictions are in line with piloted flight simulation data, suggesting that the method may be used not only for real-time control, but also potentially for reachability predictions in the autorotation flare.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Abbreviations
ACAH | Attitude Command/Attitude Hold |
DI | Dynamic Inversion |
EMF | Explicit Model Following |
ETPS | Empire Test Pilot School |
NDI | Nonlinear Dynamic Inversion |
PI | Proportional–Integral |
PID | Proportional–Integral–Derivative |
RCAH | Rate Command/Attitude Hold |
TRC | Translational Rate Command |
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Command | (Rad/s) | |
---|---|---|
Roll Attitude, | ||
Pitch Attitude, | ||
Yaw Rate, r | - | |
Vertical Position, | - |
Control Input | Min. (deg) | Max. (deg) |
---|---|---|
Lateral Cyclic, | −7 | 7 |
Longitudinal Cyclic, | −12 | 12 |
Collective, | 6.5 | 22.5 |
Tail Rotor Collective, | −6 | 25 |
Command | (Rad/s) | |
---|---|---|
Longitudinal Speed, | 1 | 0.7 |
Lateral Speed, | 1 | 0.7 |
(Rad/s) | p | ||
---|---|---|---|
4.5 | 0.7 | 0.75 | |
4.5 | 0.7 | 0.75 | |
2 | 0.7 | - | |
1 | 0.7 | - |
(Rad/s) | ||
---|---|---|
1 | 0.7 | |
1 | 0.7 |
24.975 | 15.1875 | 7.05 | |
24.975 | 15.1875 | 7.05 | |
4 | 4 | 4 | |
2 | 1 | - |
1.5 | 0.5625 | |
1.5 | 0.5625 |
(ft/s) | (ft/s) | (deg) | q (deg/s) | (%) | |
---|---|---|---|---|---|
Successful | |||||
Marginal |
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Saetti, U.; Rogers, J.; Alam, M.; Jump, M. Tau Theory-Based Flare Control in Autonomous Helicopter Autorotation. Aerospace 2024, 11, 33. https://doi.org/10.3390/aerospace11010033
Saetti U, Rogers J, Alam M, Jump M. Tau Theory-Based Flare Control in Autonomous Helicopter Autorotation. Aerospace. 2024; 11(1):33. https://doi.org/10.3390/aerospace11010033
Chicago/Turabian StyleSaetti, Umberto, Jonathan Rogers, Mushfiqul Alam, and Michael Jump. 2024. "Tau Theory-Based Flare Control in Autonomous Helicopter Autorotation" Aerospace 11, no. 1: 33. https://doi.org/10.3390/aerospace11010033
APA StyleSaetti, U., Rogers, J., Alam, M., & Jump, M. (2024). Tau Theory-Based Flare Control in Autonomous Helicopter Autorotation. Aerospace, 11(1), 33. https://doi.org/10.3390/aerospace11010033