Adaptive Modified RISE-based Quadrotor Trajectory Tracking with Actuator Uncertainty Compensation

This paper presents an adaptive robust nonlinear control method, which achieves reliable trajectory tracking control for a quadrotor unmanned aerial vehicle in the presence of gyroscopic effects, rotor dynamics, and external disturbances. Through novel mathematical manipulation in the error system development, the quadrotor dynamics are expressed in a control-oriented form, which explicitly incorporates the uncertainty in the gyroscopic term and control actuation term. An adaptive robust nonlinear control law is then designed to stabilize both the position and attitude loops of the quadrotor system. A rigorous Lyapunov-based analysis is utilized to prove asymptotic trajectory tracking, where the region of convergence can be made arbitrarily large through judicious control gain selection. Moreover, the stability analysis formally addresses gyroscopic effects and actuator uncertainty. To illustrate the performance of the control law, comparative numerical simulation results are provided, which demonstrate the improved closed-loop performance achieved under varying levels of parametric uncertainty and disturbance magnitudes

Robust structural feedback linearization based on the nonlinearities rejection

International audienceIn this paper, we consider a class of affine control systems and propose a new structural feedback linearization technique. This relatively simple approach involves a generic linear-type control scheme and follows the classic failure detection methodology. The robust linearization idea proposed in this contribution makes it possible an effective rejection of nonlinearities that belong to a specific class of functions. The nonlinearities under consideration are interpreted here as specific signals that affect the initially given systems dynamics. The implementability and efficiency of the proposed robust control methodology is illustrated via the attitude control of a PVTOL

Reference Governors for MIMO Systems and Preview Control: Theory, Algorithms, and Practical Applications

The Reference Governor (RG) is a methodology based on predictive control for constraint management of pre-stablized closed-loop systems. This problem is motivated by the fact that control systems are usually subject to physical restrictions, hardware protection, and safety and efficiency considerations. The goal of RG is to optimize the tracking performance while ensuring that the constraints are satisfied. Due to structural limitations of RG, however, these requirements are difficult to meet for Multi-Input Multi-Output (MIMO) systems or systems with preview information. Hence, in this dissertation, three extensions of RG for constraint management of these classes of systems are developed. The first approach aims to solve constraint management problem for linear MIMO systems based on decoupling the input-output dynamics, followed by the deployment of a bank of RGs for each decoupled channel, namely Decoupled Reference Governor (DRG). This idea was originally developed in my previous work based on transfer function decoupling, namely DRG-tf. This dissertation improves the design of DRG-tf, analyzes the transient performance of DRG-tf, and extends the DRG formula to state space representations. The second scheme, which is called Preview Reference Governor, extends the applicability of RG to systems incorporated with the preview information of the reference and disturbance signals. The third subject focuses on enforcing constraints on nonlinear MIMO systems. To achieve this goal, three different methods are established. In the first approach, which is referred to as the Nonlinear Decoupled Reference Governor (NL-DRG), instead of employing the Maximal Admissible set and using the decoupling methods as the DRG does, numerical simulations are used to compute the constraint-admissible setpoints. Given the extensive numerical simulations required to implement NL-DRG, the second approach, namely Modified RG (M-RG), is proposed to reduce the computational burden of NL-DRG. This solution consists of the sequential application of different RGs based on linear prediction models, each robustified to account for the worst-case linearization error as well as coupling behavior. Due to this robustification, however, M-RG may lead to a conservative response. To lower the computation time of NL-DRG while improving the performance of M-RG, the third approach, which is referred to as Neural Network DRG (NN-DRG), is proposed. The main idea behinds NN-DRG is to approximate the input-output mapping of NL-DRG with a well-trained NN model. Afterwards, a Quadratic Program is solved to augment the results of NN such that the constraints are satisfied at the next timestep. Additionally, motivated by the broad utilization of quadcopter drones and the necessity to impose constraints on the angles and angle rates of drones, the simulation and experimental results of the proposed nonlinear RG-based methods on a real quadcopter are demonstrated

Control de robots móviles autónomos en formación usando el esquema líder-seguidor

El concepto de robots trabajando en conjunto viene siendo cada vez más popular gracias a los avances tecnológicos de la autonomía en robots y a la reducción de riesgos al momento de realizar tareas peligrosas para los seres humanos. Debido a esto se propone el desarrollo de dos sistemas de control para la formación de robots móviles autónomos, que pueden ser utilizados en distintos ámbitos como operaciones militares, búsqueda y rescate, vigilancia, reconocimiento de terrenos y/u objetos en específico, exploración de nuevos hábitats, entre otros. Existen tres tipos de soluciones propuestas en la literatura, estos son la estrategia de estructuras virtuales, la basada en comportamientos y el método líder-seguidor, el cual se va a emplear en esta tesis. Se centrará en el modelamiento, inicialización y control de robots no holonómicos en formación, siguiendo a un robot líder el cual guiará al grupo a través de una trayectoria definida. Se usará el modelo Ackerman de robots móviles junto con la teoría de Linealización por Aproximación y Linealización Entrada-Salida para controlar a cada robot utilizando conjuntos de ecuaciones diferenciales que modelan a la formación. Estas ecuaciones utilizan la distancia y el ángulo de visibilidad entre un líder y su seguidor para determinar cómo se moverán al momento de llegar a su posición dentro del grupo. Finalmente se realizan simulaciones con el software MATLAB variando en formaciones y trayectorias, para analizar la estabilidad y validar el comportamiento de los sistemas diseñados, encontrando a grandes rasgos que ambos controladores son efectivos en realizar la formación deseada desde sus posiciones iniciales, evitando colisiones. Adicionalmente, el grupo de robots es guiada por el robot líder sin inconvenientes, manteniendo estable la estructura de la formación