author = "Romero, Alessandro Gerling and Souza, Luiz Carlos Gadelha de",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Universidade Federal do ABC (UFABC)}",
                title = "Optimal factorization of the state-dependent Riccati equation 
                         technique in a satellite attitude and orbit control system",
                 year = "2019",
         organization = "International Conference on Structural Engineering Dynamics",
             abstract = "The satellite attitude and orbit control system (AOCS) can be 
                         designed with success by linear control theory if the satellite 
                         has slow angular motions and small attitude maneuver. However, for 
                         large and fast maneuvers, the linearized models are not able to 
                         represent all the perturbations due to the effects of the 
                         nonlinear terms present in the dynamics and in the actuators 
                         (e.g., saturation). Therefore, in such cases, it is expected that 
                         nonlinear control techniques yield better performance than the 
                         linear control techniques. One candidate technique for the design 
                         of AOCS control law under a large maneuver is the State-Dependent 
                         Riccati Equation (SDRE). SDRE entails factorization (that is, 
                         parameterization) of the nonlinear dynamics into the state vector 
                         and the product of a matrix-valued function that depends on the 
                         state itself. In doing so, SDRE brings the nonlinear system to a 
                         (nonunique) linear structure having state-dependent coefficient 
                         (SDC) matrices and then it minimizes a nonlinear performance index 
                         having a quadratic-like structure. The nonuniqueness of the SDC 
                         matrices creates extra degrees of freedom, which can be used to 
                         enhance controller performance, however, it poses challenges since 
                         not all SDC matrices fulfill the SDRE requirements. Moreover, 
                         regarding the satellite's kinematics, there is a plethora of 
                         options, e.g., Euler angles, Gibbs vector, modified Rodrigues 
                         parameters (MRPs), quaternions, etc. Once again, some kinematics 
                         formulation of the AOCS do not fulfill the SDRE requirements. In 
                         this paper, we evaluate the factorization options (SDC matrices) 
                         for the AOCS exploring the requirements of the SDRE technique. 
                         Considering a Brazilian National Institute for Space Research 
                         (INPE) typical mission, in which the AOCS must stabilize a 
                         satellite in three-axis, the application of the SDRE technique 
                         equipped with the optimal SDC matrices can yield gains in the 
                         missions. The initial results show that MRPs for kinematics 
                         provides an optimal SDC matrix.",
  conference-location = "Viana do Castelo, Portugal",
      conference-year = "24-26 June",
             language = "en",
        urlaccessdate = "17 abr. 2021"