Fractional-order Control For Photoelectric Tracking System

The photoelectric tracking system is a highly accurate visual axis servo system,which can well isolate the carrier disturbance affected by the visual axis to achieve accurate tracking of the target.However,in practical applications,The photoelectric tracking system is susceptible to the vibration of the carrier and its various disturbances,causing the visual axis to sway,causing the image to be blurred and even losing the target in severe cases.In this paper,by studying the defects of the system,the fractional order control algorithm is applied to the system,so that the control accuracy of the system meets the actual requirements.The fractional order control algorithm in this paper has a good control effect on other servo systems with higher performance requirements.The research content of this thesis includes(1)System Model Analysis of Photoelectric Stabilization PlatformIn this paper,the traditional modeling method is used to model the outer frame,middle frame and inner frame of the photoelectric stability platform.In the modeling process,the carrier base coordinate system,the outer frame coordinate system,the middle frame coordinate system and the inner frame coordinate system are respectively established,and the transformation relationship of the three frames angular velocity in each coordinate system is analyzed in detail.Based on the transformation relationship,the dynamic model and electromechanical model of each framework are analyzed and simplified into a second-order system model.(2)System Model Analysis of Additive Decomposition TheoryBecause of using the traditional method to model the controlled object,the influence of parameter variation on the system is not considered.In this paper,based on the traditional modeling idea,the additive decomposition theory is used to decompose the system into the main system and auxiliary.system.For the main system,an acceleration-based fractional-order PID control method and a fractional-order terminal sliding mode control method are proposed.Achieve high-precision tracking of moving targets.A fractional-order disturbance observer and a fractional-order sliding mode compensator based on velocity signals are proposed for theauxiliary system.The order of the fractional-order disturbance observer can be arbitrarily selected within the real range,which can better solve the interference suppression and estimation.Compensation,designed for the fast-changing interference of the system,designed fractional sliding mode compensator.And the finite-time convergence theory is used to prove that the system error can converge to zero in a finite time to ensure the stability of the visual axis.(3)Research on Double Closed Loop Control Based on Photoelectric Tracking SystemAiming at the tracking accuracy of the photoelectric tracking system,which is susceptible to nonlinear interference such as frictional moment,a fractional-order terminal sliding mode control method based on fractional-order disturbance observer is adopted.The inner loop of the system adopts a fractional-order disturbance observer based on the velocity signal to ensure the stability of the visual axis.The outer loop of the system adopts a fractional-order terminal sliding mode controller,and the fractional-order calculus is added on the basis of the terminal sliding mode theory,thereby effectively weakening Chattering,combined with finite time convergence theory,ensures high-precision tracking control in a limited time.The simulation results show that the control method in this paper has better control effect than the traditional integral order compound control method.