More Like this

1. Static anti-windup compensator design for autonomous guidance and control of quadrotors

   https://doi.org/10.1080/00207179.2025.2454910  

   Shahbazzadeh, Majid; Richards, Christopher M (January 2025, International Journal of Control)

   In this paper, the problem of anti-windup compensator (AWC) design for implementation in the autonomous guidance and control of quadrotors is addressed. The flight environment contains obstacles with no prior knowledge of their locations. Instead, obstacles location are determined in real time, and the locations are used by a guidance algorithm for avoidance. Wind disturbances are also considered since their presence can potentially result in saturation of the propellers. When this occurs, the flight can become unstable, leading to a crash. Designing an AWC to mitigate the effects of saturation in the control system of a quadrotor can be a challenging task due to the heavy couplings and complex nonlinear dynamics. For this reason, we propose a new structure to design a static AWC-based control system to solve this problem. The effectiveness of the proposed theoretical results are verified by comparing results from simulation experiments. 

   more » « less
2. Anti-Windup Compensation for Quadrotor Trajectory Tracking With External Disturbances

   https://doi.org/10.1109/LCSYS.2024.3516635  

   Shahbazzadeh, Majid; Richards, Christopher M (December 2024, IEEE Control Systems Letters)

   Tarbouriech, S (Ed.)

   This letter considers the problem of trajectory tracking for quadrotors operating in wind conditions that result in propeller thrust saturation. To address this problem, an anti-windup compensator (AWC) is developed to reduce the tracking performance degradation and destabilizing effects from thrust saturation. Relationships are derived showing how the tracking error and AWC states are influenced by the wind disturbance and saturation, and how the influences depend on the controller and AWC gains. As a result, these gains can be tuned to achieve desired performance levels. Simulation results are presented to validate the effectiveness of the proposed method. 

   more » « less
3. Vision-Based Safety-Critical Landing Control of Quadrotors With External Uncertainties and Collision Avoidance

   Lin, J; Miao, Zhiqiang; Wang, Yaonan; Wang, Hesheng; Wang, Xiangke; Fierro, Rafael (July 2024, IEEE Transactions on Control Systems Technology)

   This article addresses the quadrotors’ safety-critical landing control problem with external uncertainties and collision avoidance. A geometrically robust hierarchical control strategy is proposed for an underactuated quadrotor, which consists of a slow outer loop controlling the position and a fast inner loop regulating the attitude. First, an estimation error quantified (EEQ) observer is developed to identify and compensate for the target’s linear acceleration and the translational disturbances, whose estimation error has a nonnegative upper bound. Furthermore, an outer-loop controller is designed by embedding the EEQ observer and control barrier functions (CBFs), in which the negative effects of external uncertainties, collision avoidance, and input saturation are thoroughly considered and effectively attenuated. For the inner-loop subsystem, a geometric controller with a robust integral of the sign of the error (RISE) control structure is developed to achieve disturbances rejection and asymptotic attitude tracking. Based on Lyapunov techniques and the theory of cascade systems, it is rigorously proven that the closed-loop system is uniformly ultimately bounded. Finally, the effectiveness of the proposed control strategy is demonstrated through numerical simulations and hardware experiments. 

   more » « less
4. Adaptive formation control architectures for a team of quadrotors with multiple performance and safety constraints

   https://doi.org/10.1002/rnc.6824  

   Hu, Zhongjun; Jin, Xu (September 2023, International Journal of Robust and Nonlinear Control)

   Abstract In this work, we propose a novel adaptive formation control architecture for a group of quadrotor systems, under line‐of‐sight (LOS) distance and relative distance constraints as well as attitude constraints, where the constraint requirements can be both asymmetric and time‐varying in nature. The LOS distance constraint consideration ensures that each quadrotor is not deviating too far away from its desired flight trajectory. The LOS relative inter‐quadrotor distance constraint is to guarantee that the LOS distance between any two quadrotors in the formation is neither too large (which may result in the loss of communication between quadrotors, for example) nor too small (which may result in collision between quadrotors, for example). The attitude constraints make sure that the roll, pitch, and yaw angles of each quadrotor do not deviate too much from the desired profile. Universal barrier functions are adopted in the controller design and analysis, which is a generic framework that can address system with different types of constraints in a unified controller architecture. Furthermore, each quadrotor's mass and inertia are unknown, and the system dynamics are subjected to time‐varying external disturbances. Through rigorous analysis, an exponential convergence rate can be guaranteed on the distance and attitude tracking errors, while all constraints are satisfied during the operation. A simulation example further demonstrates the efficacy of the proposed control framework. 

   more » « less
5. Distributed Cooperative Control of Multiple UAVs with Uncertainty

   Ahmed, Shihab; Dong, Wenjie (November 2022, International journal of dynamics and control)

   This paper considers the formation flying of multiple quadrotors with a desired orientation and a leader. In the formation flying control, it is assumed that the desired formation is time-varying and there are the system uncertainty and the information uncertainty. In order to deal with different uncertainties, a backstepping-based approach is proposed for the controller design. In the proposed approach, different types of uncertainties are considered in different steps. By integrating adaptive/robust control results and Laplacian algebraic theory, distributed robust adaptive control laws are proposed such that the formation errors exponentially converge to zero and the attitude of each quadrotor exponentially converges to the desired value. Simulation results show the effectiveness of the proposed algorithms. 

   more » « less