Research On Characteristic Modeling And Adaptive Control Technique For A Kind Of Alternating Current Servo Systems

In modern warfare,precision-guided aerial targets,such as high-speed missiles and intelligent munitions,are difficult to detect and predict the motion trajectory,which brings great pressure to national air defense system.Vehicle-mounted anti-air weapons,which have the advantages of quick response,quick retreat and high cost-effectiveness ratio,play an important role in modern air defense system.Vehicle-mounted multiple rocket launchers,which have the advantages of long range and high accuracy,can be equipped with high explosive,incendiary bomb and cluster bomb and destroy the key ground targets at long range.With the development of military technology,higher requirements are put forward for the rapidity,precision,robustness and dynamic performance of vehicle-mounted weapon servo systems.The design and control of servo systems are facing new challenges.In order to meet the demand of vehicle-mounted weapon servo systems,the research on characteristic modeling and adaptive control technique for a kind of alternating current servo systems is carried out.The characteristic modeling method of servo systems is studied,which has the advantages of low order,less identification parameters,fast convergence and the ability of discribing large-range variation of system parameters.The inner-loop compensation method is studied,which can restrain the influence of external disturbance and internal nonlinearity.The characteristic model is combined with terminal sliding-model control and the high performance position control method is studied.The effectiveness of the proposed control strategies is verified by experimental results.The main contents of this paper are as follows:(1)Focusing on the characteristic modeling issue of a kind of alternating current servo systems,a derivation procedure from dynamics model to characteristic model is proposed,the scope and constraints of characteristic parameters are analyzed,some factors which affect parameter identification are revealed.In the dynamics model of servo system,the friction Lu Gre model and the backlash deadzone model are substituted by smoothed models.Based on differential geometry theory,the dynamics model is transformed to a normal form by the diffeomorphism transformation.The characteristic model of servo system is then deduced by the discretization of normal form.The the scope and constraints of characteristic parameters are analyzed in consideration of servo system characteristics and sampling time.The equivalence between characteristic model and dynamics model is verified by simulations results.Some factors which affect parameter identification are also revealed by simulations results,which show that the characteristic model can adapt to different load inertia,but load torque disturbance and backlash effect greatly affect the parameter identification and modeling accuracy.Therefore,compensation methods need to be studied to overcome these adverse effects.(2)In torque-impacted servo systems,the friction nonlinearity,strong torque disturbance and large-range load inertia variation greatly affect control performance.To deal with this issue,a lumped disturbance third-order extended state observer(TESO)based target current compensator and a characteristic model based discrete-time adaptive terminal sliding-mode position controller(DATSMC)are proposed.The friction moment,strong torque disturbance and other uncertainties in dynamics model are encapsulated into lumped disturbances,which is observed and compensated by TESO and target current compensator respectively.The method of observer parameters selection is given,and the convergence of observation error is proved.Based on the dynamics model of generalized servo system,which contains target current compensator and velocity controller,the characteristic model is established,and the DATSMC is then designed.The scope of control parameters is given,and the finite-time boundedness of closed-loop system is proved.The simulations results show that the proposed DATSMC can adapt to large-range load inertia variation,the proposed target current compensator can compensate the influence of strong torque disturbance.(3)In gear transmission servo systems,the backlash nonlinearity,transmission flexibility and load inertia variation greatly affect control performance.To deal with this issue,a lumped disturbance fifth-order extended state observer(FESO)based target current compensator and a characteristic model based discrete-time adaptive second-order terminal sliding-mode position controller(DASTSMC)are proposed.The nonlinear part of backlash model is regarded as equivalent disturbance,which together with other disturbance and uncertainties in dynamics model are encapsulated into lumped disturbances.A FESO and a target current compensator are designed to observe and compensate the lumped disturbances respectively.The method of observer parameters selection is given,and the convergence of observation error is proved.Based on the dynamics model of generalized servo system,which contains target current compensator and velocity controller,the characteristic model is established,and the DASTSMC is then designed.The scope of control parameters is given,and the finite-time boundedness of closed-loop system is proved.The simulations results show that the proposed DASTSMC satisfies the performance indexes of three typical reference signals,and can adapt to load inertia variation and restrain disturbance,the proposed target current compensator can further compensate the backlash effect.(4)Based on the self-developed servo system experimental platform,an experimental verification method of integrated control algorithms for servo systems under complicated conditions is proposed.The method of changing load inertia and generating strong torque disturbance is designed.The backlash nonlinearity,friction nonlinearity and transmission flexibility are also introduced to simulate the operating state of weapon servo systems under complicated conditions.On the experimental platform,the engineering implementation and experimental verification of integrated control algorithms for servo systems are carried out from current loop,velocity loop and position loop respectively.The experiment of rapid gun adjustment and anti-disturbance is carried out,the experimental results show that the DATSMC+TESO can adapt to large-range load inertia variation and restrain the influence of strong torque disturbance.The experiment of high-precision maneuvering target tracking is carried out,the experimental results show that the DASTSMC+FESO can track variable instruction signal with high precision,adapt to different load inertia and further compensate the backlash effect.