Analysis of Dynamical Models and Design of Feedback Control Laws for E-sail Deployment Operations

Abstract

Las Velas Eléctricas Solares son un sistema de propulsión continua basado en la interacción electrostática entre el viento solar y el campo eléctrico creado por un conjunto de cables muy esbeltos cargados eléctricamente. Con aplicaciones en misiones interplanetarias para vehículos de pequeño y mediano tamaño, el despliegue de este conjunto de cables es uno de los principales problemas a resolver para la adecuada implementación de este tipo de dispositivos. De esta manera, el objetivo del proyecto es analizar de manera extensa el modelo dinámico y el diseño de algoritmos de control tanto lineales como no lineales para maniobras de despliegue de Velas Eléctricas Solares, analizando el rendimiento de las leyes de control desarrolladas a través de la implementación de un Filtro de Kalman Extendido.

In this master’s thesis, an assessment of the dynamic modelling and control of E-sail deployment operations has been performed. In particular, the two-dimensional equations of motion of both tangential and radial symmetrical deployment strategies have been derived using a Lagrangian-based approximation. For these dynamical models, both linear and non-linear control full state laws have been developed, as well as an Extended Kalman Filter (EKF), using the available actuators and sensors, respectively. The performance of the output feedback control laws (this is, the feedback control laws computed using the state estimated by the EKF) has been finally assessed taking into account a realistic level of noise within the measurements. Thus, the implemented control algorithms proved the controllability of both deployment strategies, whereas the order of magnitude of the obtained errors were reasonable given the significance of the introduced perturbations. Additionally, the radial deployment strategy presented significantly lower control requirements with respect to the tangential deployment strategy in terms of the torque to be applied into the hub spin axis, despite its higher mechanical complexity and number of control variables.