Aerodynamic Interaction Minimization in Coaxial Multirotors via Optimized Control Allocation
Abstract
:1. Introduction
1.1. Related Work
1.2. Contributions
2. Coaxial Rotor
2.1. Model
2.2. Identification Method
3. Coaxial Rotor Experiments and Analysis
3.1. Parameter Identification
3.2. Tolerance Analysis
3.3. Efficiency
4. Coaxial Control Allocation Strategies
4.1. Reduced Coaxial Mixer
4.2. Coaxial Mixer
Algorithm 1 Coaxial Control Allocation algorithm |
5. Control Allocation Experiments
5.1. Experimental Setup
5.2. Control Allocation Implementation
5.2.1. Reduced Coaxial Mixer
5.2.2. Coaxial Mixer
5.2.3. Standard Mixer
5.3. Software-In-The-Loop
5.4. Flight Test
6. Conclusions
- Incorporating aerodynamic interactions into lower rotor models results in a reduction of both thrust and torque errors compared to standard models, with a decrease in thrust error of approximately 12 N and a reduction in total torque error of about 0.043 Nm.
- Adoption of a LASSO-based technique as the identification method for model parameters prevents model overfitting and decreases initial model complexity, thereby improving computational efficiency, with the price of lower accuracy, but still a better one with respect to state-of-the-art solutions. Relaxation of LASSO tolerance results in a further reduction in model complexity, resulting in a quadratic model.
- Two coaxial mixer strategies were implemented based on coaxial rotor models: Coaxial Mixer and Reduced-Coaxial Mixer. The Coaxial Mixer utilizes the pseudo-inversion of a static control allocation matrix, while for Reduced-Coaxial Mixer rotor velocities are derived from the solution of second-order equations. Both mixers improve thrust tracking accuracy and rotor efficiency compared to standard mixer solutions. Specifically:
- −
- Coaxial Mixer generates the minimum thrust and position errors but results in increased attitude error compared to the Reduced-Coaxial Mixer.
- −
- Reduced-Coaxial Mixer achieves better attitude and torque tracking but larger thrust and position errors with respect to the previous one.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Lower rotor coefficients | |||||
Thrust | |||||
2.755 | 2.166 × 10 | 1.047 × 10 | −2.547 | −37.502 | |
const | |||||
64.721 | 12.402 | 0.801 | |||
Torque | |||||
1.685 × 10 | −9.398 × 10 | 0.307 | 4.991 × 10 | −0.695 | |
const | |||||
1.466 | 0.573 | 2.987 × 10 | |||
Upper rotor coefficients | |||||
const | |||||
Thrust | 55.9517 | 22.4464 | 1.4629 × 10 | ||
Torque | 1.2437 | 0.7155 | 2.1277 × 10 |
Coaxial Thrust | Coaxial Torque | |||||
---|---|---|---|---|---|---|
RMSE | NRMSE | R-Value | RMSE | NRMSE | R-Value | |
CRM | 1.1614 | 0.0106 | 0.9997 | 0.0241 | 0.0072 | 0.9998 |
R-CRM | 4.2116 | 0.0385 | 0.9956 | 0.1016 | 0.0305 | 0.9971 |
SRM [11] | 12.8323 | 0.0775 | 0.9718 | 0.2029 | 0.0523 | 0.9911 |
CPCM [21] | 12.7638 | 0.0771 | 0.9721 | 0.2029 | 0.0523 | 0.9911 |
Accuracy | Tolerance | Model Complexity | |
---|---|---|---|
CRM | ↑ | ↓ | ↑ |
R-CRM | ↑ | ↓ | ↑ |
Errors | Control Allocation Method | ||
---|---|---|---|
Coaxial Mixer (Section 4.2) | Standard Mixer [5] | R-Coaxial Mixer (Section 4.1) | |
0.3653 | 0.3656 | 0.3652 | |
0.3662 | 0.3661 | 0.3659 | |
0.0698 | 0.6373 | 0.3335 | |
0.10785 | 0.10451 | 0.10624 | |
0.08570 | 0.08423 | 0.0850 | |
0.4667 | 0.00105 | 0.00108 | |
0.58 | 4.78 | 2.75 |
Error Comparison Desired and Estimated Moments and Thrust. | ||
---|---|---|
Coaxial Mixer (Section 4.2) | Standard Mixer [5] | |
0.019633, 0.009605, 0.110167 | 0.141473, 0.076642, 0.3597 | |
11.017573 | 24.684715 |
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Berra, A.; Trujillo Soto, M.Á.; Heredia, G. Aerodynamic Interaction Minimization in Coaxial Multirotors via Optimized Control Allocation. Drones 2024, 8, 446. https://doi.org/10.3390/drones8090446
Berra A, Trujillo Soto MÁ, Heredia G. Aerodynamic Interaction Minimization in Coaxial Multirotors via Optimized Control Allocation. Drones. 2024; 8(9):446. https://doi.org/10.3390/drones8090446
Chicago/Turabian StyleBerra, Andrea, Miguel Ángel Trujillo Soto, and Guillermo Heredia. 2024. "Aerodynamic Interaction Minimization in Coaxial Multirotors via Optimized Control Allocation" Drones 8, no. 9: 446. https://doi.org/10.3390/drones8090446