Controller Design For A Small Laser-guided Bomb With Large Mass Center Bias Disturbances

With the rapid development of unmanned aerial vehicle(UAV),a novel kind of small laser-guided bomb(SLGB)which utilizes UAV as a platform,has been widely studied for various countries in the world as its great important role in the precise strike.To further increase the range of SLGB,the solid-rocket motor has been presented to improve the initial velocity of SLGB in recent years.However,multiple aerodynamic uncertainties,large gravity variations,unknown disturbances and un-modeled dynamics may come into action during the whole flight phase of SLGB.Therefore,the control design for SLGB is required to be strong robust in the presence of multiple disturbances and uncertainties.Firstly,this dissertation is devoted to developing the current research state of SLGB in detail.The characteristics of SLGB and its problem for control system design have been analyzed,and plenty of controllers for SLGB have also been researched in detail.Secondly,the six-degree-of-freedom(6DOF)dynamic models of SLGB are both developed in the presence of powered flight phase under the action of solid-rocket motor and unpowered glide flight phase.Meanwhile,the small perturbation linearized equations of three decoupled channels for the 6DOF dynamic model of SLGB are derived,which can be utilized to design the corresponding controllers for the next section.Subsequently,H_?control is studied according to the characteristics of SLGB.The traditional control problem for SLGB can be translated into H_?mixed sensitivity control problem,and then it can be solved by the toolbox of Mrct in the Matlab software.Considering the practical application of engineering,a balanced truncation method is proposed to reduce the order of H_?controller.Furthermore,the control parameters will be optimized by the fish swarm optimization method.The global performances for both mixed scheduling algorithm and D scheduling algorithm are compared.Simulation results indicate that the D scheduling algorithm,which has been reduced order and the control parameters are optimized,has stronger robustness and more disturbance rejection performances than the mixed scheduling algorithm.Finally,due to the problem of conservation and the complicated design process for H_?controller,model reference sliding mode control(MRSMC)is presented to improve the performance of controller for SLGB.Simulation results including single point simulation and the whole flight phase nonlinear simulation are carried out to illustrate the effectiveness of the proposed control scheme.To further improve the performance of MRSMC,a novel extended state observer based model reference sliding mode control has been developed to increase the robustness of traditional MRSMC.More specially,simulation results including single point simulation,whole flight phase nonlinear simulation,Monte Carlo simulation and different ranges simulations are presented to demonstrate the efficacy of the proposed control law.