Lift-Plus-Cruise Aircraft Modeling, Guidance, Adaptive Control, and Flight Simulation

2024

• Computer Science
• Aeronautics
• Computer Science

In the rapidly evolving sectors of Unmanned Aircraft Systems (UAS) and Urban Air Mobility (UAM), there is an increasing need for technologies that can cater to both Department of Defense (DoD) and commercial applications. These applications range from logistics and supply delivery to disaster relief, search and rescue operations, air taxi services, and operations in underdeveloped areas. This paper presents the development and testing of an adaptive flight control system for lift-plus-cruise eVTOL aircraft, aimed at providing a smooth transition from hover/low-speed flight to forward/high-speed flight. The proposed framework consists of the aircraft model, the guidance system that translates pilot inceptor commands to control inputs, and the neural network adaptive controller that stabilizes the aircraft. The simulation is performed to demonstrate the robustness and adaptability of the system for UAM in diverse operational contexts.

Observer Controller Identification of a Medium-Weight Co-axial Octocopter

AIAA SCITECH 2022 Forum · 2022 · 1 citations

• Computer Science
• Computer Science
• Control engineering

View Video Presentation: https://doi.org/10.2514/6.2022-1083.vid In this work, system identification of the open-loop airframe characteristics of a medium-weight co-axial octocopter is performed using closed-loop simulated data. Data is generated from the closed-loop octocopter model at hover using moments and thrust as excitation signals. Observer/Controller Identification (OCID) is then used to estimate the observer, controller and system Markov parameters from the generated data. The Markov parameters are used to form the Hankel matrices, that form the basis of the Eigensystem Realization Algorithm (ERA) used to determine the minimal realization of the system matrices. The effect of noise on the system identification process is analyzed by computing the Mode Singular Values (MSV). The use of Eigensystem Realization Algorithm with Data Correlations (ERA/DC) is also explored to demonstrate the improvement in system identification in the presence of noise. The system identification process presented in this work can be used to determine the system’s modes that help in analyzing the handling qualities of the aircraft, which can be useful in improving simulation model fidelity and estimating higher order dynamics.identification process presented in this work can be used to determine the system’s modes that help in analyzing the handling qualities of the aircraft which, in turn, can be useful in improving simulation model fidelity and estimating higher order dynamics.

A graph placement methodology for fast chip design

Nature · 2021 · 564 citations

• Computer Science
• Computer Science
• Theoretical computer science

Robust Outlier-Adaptive Filtering for Vision-Aided Inertial Navigation

Sensors · 2020 · 13 citations

• Artificial Intelligence
• Computer Science
• Artificial Intelligence

With the advent of unmanned aerial vehicles (UAVs), a major area of interest in the research field of UAVs has been vision-aided inertial navigation systems (V-INS). In the front-end of V-INS, image processing extracts information about the surrounding environment and determines features or points of interest. With the extracted vision data and inertial measurement unit (IMU) dead reckoning, the most widely used algorithm for estimating vehicle and feature states in the back-end of V-INS is an extended Kalman filter (EKF). An important assumption of the EKF is Gaussian white noise. In fact, measurement outliers that arise in various realistic conditions are often non-Gaussian. A lack of compensation for unknown noise parameters often leads to a serious impact on the reliability and robustness of these navigation systems. To compensate for uncertainties of the outliers, we require modified versions of the estimator or the incorporation of other techniques into the filter. The main purpose of this paper is to develop accurate and robust V-INS for UAVs, in particular, those for situations pertaining to such unknown outliers. Feature correspondence in image processing front-end rejects vision outliers, and then a statistic test in filtering back-end detects the remaining outliers of the vision data. For frequent outliers occurrence, variational approximation for Bayesian inference derives a way to compute the optimal noise precision matrices of the measurement outliers. The overall process of outlier removal and adaptation is referred to here as "outlier-adaptive filtering". Even though almost all approaches of V-INS remove outliers by some method, few researchers have treated outlier adaptation in V-INS in much detail. Here, results from flight datasets validate the improved accuracy of V-INS employing the proposed outlier-adaptive filtering framework.

Cooperative Output Regulation of Heterogeneous Multiagent Systems: A Global Distributed Control Synthesis Approach

IEEE Transactions on Automatic Control · 2020 · 29 citations

• Computer Science
• Mathematical optimization
• Computer Science

Agent-wise local design methods to synthesize distributed control gains focus on the individual dynamics of each agent to guarantee the overall stability of the system. They are powerful tools due to their scalability. However, the agent-wise local design methods are incapable of maximizing the overall system performance through, for example, decay rate assignment. On the other hand, design methods, which are predicated on a global condition, leads to nonconvex optimization problems. This article considers a global design of an internal model-based distributed dynamic state feedback control law for the linear cooperative output regulation problem. We present a convex formulation of this global design problem based on a structured Lyapunov inequality. Then, the existence of solutions to the structured Lyapunov inequality is investigated. Specifically, we analytically show that the solutions exist for the systems satisfying the agent-wise local sufficient condition. Finally, we compare the proposed method with the agent-wise local design method through numerical examples in terms of conservatism, performance maximization, graph dependency, and scalability.