ADRC Based Study On Stable Tracking Control Of Ship-borne Photoelectric Platform

In recent years,with the rapid development of the modern military defense technology,the photoelectric stabilized platform attracts the attention of all countries as a core component,and its control system plays a key role.The tracking precision,as one of important indexes of the control system,is to measure the performance of the photoelectric stabilized platform,and the stability control is the basic precondition to achieve high precision tracking control.The carrier of the photoelectric stabilized platform may be aircrafts,ships or tanks and so on,thus,its inadequate working conditions and structure complexity of the tracking control system itself will bring about the strong coupling,nonlinearity and even time delay problem,and the system also will be affected by friction disturbance,moment of inertia uncertainty,noise of measuring element and external uncertain disturbance(e.g.ship movement,wind moment and temperature variation and so on).In summary,the existence of these unfavorable factors will influence the stability of the photoelectric stabilized platform and make traditional control methods meet requirements of multi-performance indicators difficultly.In serious case,the mission may even not be completed at all when performing complex tasks.Based on these reasons,the goal of this paper is to propose control schemes with high-security,strong stability,strong anti-disturbance ability and strong robustness for the photoelectric stabilized platform.Combining with active disturbance rejection control(ADRC),dynamic surface control(DSC),Smith predictor control,extended state observer(ESO)and cascaded control structure,novel stable tracking control schemes are analyzed with both theoretical analysis and numerical simulation.The main research contents of this paper are as follows:This paper mainly researches the ship-borne photoelectric platform.Its physical construction is composed of two-frame two-axis structure that is the pitch and azimuth axis.The main purpose is to search and track the target stably via the servo control system.Firstly,the composition and working principle of the system are introduced to build the mathematical model of the servo control system.Meanwhile,factors affecting the stable tracking of the system(including the internal uncertainty and external disturbance)are qualitatively analyzed,and furthermore the effect of carrier movement on the line of slight(LOS)stability is quantitatively analyzed.Finally,some key control performance indicators and problems of the photoelectric platform which need to be solved are proposed.Considering characteristics of nonlinearity and uncertainty,a novel control strategy based on ADRC is designed.Firstly,as for a class of nonlinear uncertainty systems,the converse Lyapunov theorem and the disturbance theory are employed to prove the stability of ADRC.It doesn't need the accurate information or mathematical model of the disturbance,and it can overcome the difficulty of defining a reasonable Lyapunov function and setting limitations of system parameters.Then,the relationship between the stability and parameters of ADRC is quantitatively analyzed based on the Bode diagram and root locus in the frequency-domain.Thereby,the parameter tuning procedure is concluded to reduce the complexity and computational expense.Meanwhile,a numerical simulation example is presented to verify the effectiveness of above conclusions.Finally,the ADRC controller is applied to the accumulator tension control of steel strip processing line to demonstrate the practicability of ADRC.On the basis of the above research,a novel feed-forward compensation active disturbance rejection control(FFC-ADRC)approach is proposed for the input time-delay problem in engineering systems.Firstly,synchronization problem of the control input signal and the output signal is realized via a feed-forward compensation based on the smith predictor which can predict the control input signal.And then combining with advantages of independent for accurate model and strong anti-disturbance ability of ADRC,it can achieve high precision and fast tracking control.This control strategy not only reduces the requirements of an accurate model in smith predictor control,but also releases the limitation of controller bandwidth resulting from the time delay,which will increase the range of the stability.Then the Lyapunov theory and the theory of the input-output stability are presented to prove the asymptotic stability strictly of the proposed control system,and parameter tuning rules are concluded.Finally,numerical simulations for first-order and second-order time delay systems with stable,critical stable or unstable poles,and different control difficulties show the effectiveness and anti-disturbance performance of the proposed design.Furthermore,when exiting perturbations of system parameters and time delay,the robustness is tested to improve the reliability and practicability of the proposed control strategy.Considering that the servo tracking system of the ship-borne photoelectric platform is affected by moment of inertia uncertainty,friction disturbance,ship movement and external uncertain disturbance,a novel dynamic surface control based on an ESO with error constraints is designed,which doesn't need accurate system model.Compared with the traditional dynamic surface control,this design can guarantee the transient performance of the tracking error(e.g.the overshoot,convergence rate and the steady state error)via a prescribed performance function,lower computational complexity and rapid convergence.Then an ESO is employed to estimate not only the position and speed of the servo stabilized platform,but also total unknown dynamics compensated in the control law,which will be used to design the controller.It can lower the requirement of linearizability for the nonlinear uncertainty dynamics in the traditional dynamic surface control,and then improve the antidisturbance ability of the proposed design.Furthermore,the conclusion is drew utilizing Lyapunov theory: the proposed design is uniformly ultimately bounded,all signals of the closed-loop control system are bounded,and the estimate error of ESO and tracking error of the design converge to a small neighbourhood around the equilibrium point.Finally,some numerical simulation results are presented to demonstrate the effectiveness and feasibility of the proposed control scheme under the circumstances of multi-disturbance.Thereby,it also concludes that it has stronger anti-interference ability and robustness.A novel disturbance suppression control scheme with double speed loop based on ADRC is proposed for the ship-borne photoelectric tracking equipment with the LOS instability and large tracking error resulting from the internal disturbance,external disturbance and noise of measuring element.Firstly,a double speed-loop structure is built using the advantage of the cascaded structure to suppress the internal disturbance and external disturbance respectively,which reduces not only the difficulty of rejecting simultaneously the internal and external disturbance and the dependence for the gyroscope,but also dependency of the anti-disturbance performance for the model parameters in single speed loop.Then combining with advantages of fast respond and strong anti-disturbance ability of ADRC to design the controller,the convergence and anti-disturbance performance are improved remarkably,so that the high precision and fast tracking control is achieved.Finally,in order to demonstrate advantages of the proposed control scheme,comparing with the other two common control schemes,simulation results show that the proposed method is effective and better than the other two control method.In the end of dissertation,the main contents are summarized and the future research works are presented.