On Path Planning And Attitude Control Of Antiship Missile

This thesis performed investigations on several issues related to the guidance and control problems for antiship missiles.Penetration capability is a crucial indicator of effectiveness for the antiship missiles. Because important large-and medium-sized target warships are equipped with multiple layer protective measures, they are able to defend a number of intensive missile attacks. Therefore, reasonable path planning for multiple antiship missiles is needed, by simultaneously regulating impact angle and impact time in an effective manner, to coordinate the mission. In practice, both the motion of the target and the fluctuations of the velocity of the antiship missiles affect the final results of a salvo attack. Moreover, the introduction of no-fly zones imposes an tremendous difficulty for path planning.In addition, some antiship missiles are designed with static instability to enhance general performance. However, this causes several control problems in reality. The path planning is normally conducted in the mid-course guidance stage wherein a satisfactory attitude control is desired. How to design an attitude control system for a statically unstable missile such that certain robustness and dynamic performance specifications can be achieved is an important problem for practitioners. It should be noted that insightful quantitative results in this field are urgently needed.The thesis mainly investigated the following four aspects of problems in terms of path planning and attitude control for antiship missiles with static instability:(1) Path planning for salvo attack based on receding horizon optimization strategy in the presence of no-fly zones.The Gauss pseudospectral method and the receding horizon optimization were combined to solve the path planning problem where the avoidance of no-fly zones was considered as a constraint.(2) Time matching scheme in the salvo attack of antiship missilesTo realize the specified impact angle and impact time accurately, the designated maneuver was presented to attenuate the fluctuations of the velocity of the missile by taking the no-fly zone constraint into account in such a way that the path can be adaptively regulated.(3) Frequency-domain analysis and design of attitude control for a statically unstable missilePID tuning mehod for attitude control was obtained based on stability margin specifications by considering the missile dynamics. Furthermore, the overall feasible stability margin area was also derived.(4) Time-domain dynamic performance analysis of attitude control for a statically unstable missileCertain parts of attitude control parameter space were connected with specific dynamic performance characteristics also by considering the missile dynamics.The major innovations of this thesis are summarized as follows:(1) A path planning algorithm to coordinate impact angle and impact time against a surface target was proposed based on the receding horizon optimization strategy while evading the no-fly zones.(2) A real-time circular manouver plus pseudospectral predictive trajectory optimization was presented to check the time errors produced by the uncertain velocity in the presence of no-fly zones. In this process, the entire path planning area was segmented and a forward searching method was proposed to speedup the optimization.(3) By approximating the actuator as a time-delay process, the PID pitch attitude tuning rule was derived on the basis of specific increasing gain margin and phase margin for a statically unstable missile. Moreover, the achievable stability margin for PID control can be explicitly plotted by approximating the decreasing gain margin and using numerical polynomial solving approaches. Hence, unacceptable stability margin requirements can be effectively avoided.(4) The relationship between the number of closed-loop step response and the PD pitch control parameters was analyzed, and the results were illustrated in the parameter space.