Hybrid BTT/STT missile autopilot design

Purpose Traditional skid-to-turn (STT) missile control mode is adopted mostly, but with the improvement of requirements for mobility and the emergence of new aerodynamic layout, a bank-to-turn (BTT) control mode gradually shows a greater advantage. However, the BTT missile also has certain defects, for example, when attacking against a maneuvering target and at the last section of guidance, the maximum lifting surface position of the missile needs to be adjusted frequently, thereby increasing the difficulty of control as well as introducing high-frequency noise. Design/methodology/approach Based on respective characteristics of the two control modes, this paper puts forward a hybrid autopilot design method based on nonlinear dynamic inversion. Firstly, the method converts overload instructions into corresponding angle instructions through the design of hybrid control guidance logic; secondly, based on the nonlinear dynamic inversion algorithm and combined with the fast-changing circuit/slowly changing circuit, a hybrid controller is designed; finally, combined with the missile mathematical model and actuator, it forms a autopilot design closed loop. Findings The simulation result shows that the non-linear dynamic inverse-based BTT/STT hybrid controller can input a track command well, normal overload and roll angle tracking performance have more advantages than the hybrid controller designed on the basis of classical control method in terms of overshooting and hysteretic characteristics. Originality/value The paper puts forward a new BTT/STT hybrid control method which has both the high mobile ability of the BTT missile and the precise control ability of the STT missile, which can adapt to the more complicated fighting environment. And, the method can effectively weaken the impact of the transformation of the control mode on the system.

On a novel equivalent control-based adaptive sliding mode approach for autopilot design of BTT missiles

This paper presents a novel equivalent control-based adaptive sliding mode control (EASMC) approach for designing the autopilot of a bank-to-turn (BTT) missile under model uncertainties and external disturbances. The sliding surface is constructed with a tracking error between the real attitude angle and the reference command. The equivalent control technique works as a mechanism for the gains over-bounded by uncertainties and this information is implemented in the adaption progress. The method guarantees that the sliding surface reaches zero in finite time and the error tracks the command value asymptotically. The advantage of this method is that the gains will be adapted to counteract uncertainties and enable the control deflection magnitude to be reduced to the minimum value, keeping the property of a finite-time convergence. The skill in choosing the gains is also given in this paper. Simulation results demonstrate that the approach proposed is able to improve the dynamic performance and robustness of a BTT missile system.