Research On Ac Servo System Of The Miniaturized Infrared Seeker

With the development of precision guidance technology, greater demands are being placed on the performance of missile seeker servo system, such as more accurate in guidance and much smaller. However, the traditional gyroscope can’t meet these requirements, while the development of MEMS gyroscope provides a new approach in solving these problems. Due to the patch and assembly errors of PCB, the motor axis and axis of gyroscope will be inconsistent. For this reason, single- axis angular rate gyroscope output coupling and eventually this will decline the precision of servo system. To solve this problem, this paper proposed gyroscope calibration and decoupling algorithm based on angular feedback. To validate proposed algorithm effective, this paper also designed a miniaturized missile seeker servo system platform according to the performance task.Firstly, this paper analyzed the relationship of yaw-pitch missile seeker servo frames’ angular velocity and the sources of assembly errors and then proposed gyroscope calibration algorithm and decoupling algorithm based on angular feedback on the basis of the analysis. The software design flows of calibration algorithm and decoupling algorithm were also given in this paper. Based on the proposed algorithm, the overall control scheme of yaw-pitch missile seeker was designed.Secondly, according to the performance task of the project, servomechanism was designed in this paper, including the selection of the structure of the program, the kind of motor and gyroscope and so on. Then the PMSM was designed reasonably. The basic parameters of the PMSM were determined by the form of rotor, the slots and poles number as well as the number of turns of windings. Besides, the electromagnetic simulation analysis was performed on the motor model and finally conclude the conclusion that the parameters of PMSM were selected reasonable by means of the analysis of extract data. In addition, limited-angle high precision magnetism encoder was designed. Relative distance between the magnetic field source and sensitive element was confirmed through magnetic simulation.Thirdly, in order to design the hardware circuit, this paper divided the circuit system into five parts: the power supply part, the control and communication part, the power drive part, feedback part and the flexible cable part. The control strategy in detail mainly designed the speed loop based on double frequency control algorithm. Furthermore, Isolation simulation was carried out to test the system’ ability to suppress the motion of missile and the result showed the designed system had a good antijamming capability.Finally, the experiment platform was constructed to validate the proposed algorithm. O n the one hand, the hardware system’s basic properties such as the yaw and pitch frame encoder, the delay and dead zone of the power switch device, the yaw and pitch frame motors’ torque coefficient and the inconsistency of axis of gyroscope and motor were tested. O n the other hand, system experiments were carried out and concluded that the double frequency control algorithm worked in small inductance motor control via the compression in current response before and after using double frequency control. Moreover, this paper also proved the proposed gyroscope calibration and decoupling algorithm was effective by simulation online.