| The iterative learning control theory is used to improve the control characteristic of electro-hydraulic force servo control system in this paper, and the proposed control method not only widen the research scope of the control theory application but also which has the theory and actual engineering significanceThe electro-hydraulic force servo control system has some merits such as great output power, high reliability, strong anti-interference ability, rapid respond speed, and simple operation, etc. Hence the system has been widespread used in various engineering practices. Especially, the system is used in the rapid and accurate respond requirement for the big power automatic control system. The dynamic characteristic of electro-hydraulic force servo control system is improved in this paper, which can not only meet various applications, and according with the continuous efforts and long-term target in this technology domain both domestic and overseas. Certainly, the dynamic characteristic improvement has very strong actual significance.The electro-hydraulic force servo control system is a system which consists of some characteristics, such as high order, strong coupled, time varying, strong nonlinear, uncertain parameters and structure, and normal endure uncertain load interference, and so on. The high accuracy control of electro-hydraulic force servo control system is difficult to realize by using the conventional control method due to these characteristics. In recent years, many intelligent control and robust control theory method is used in the system, which provides the effective way for the electro-hydraulic force servo control system with above characteristics. However, the electro-hydraulic force servo control system is simplified as linear and low order system in most method. With the increasing of tracking accuracy, dynamic respond ability, stability, and robust, the complicacy of system requires to find the more strong target and more excellent control performance of control method.The controlled object of iteration learning control method has rerun characteristic, and the control method revises the control signals by using the iteration method and before operation information, which can realizes zero error tracking task in limited time interval of controlled system. The conventional iteration learning control is well known due to the simple algorithm form and accurate tracking, which has certain merits in resolve some actual question. In order to resolve the effect of nonlinear and high order for the system characteristic, the iteration learning control is used in the electro-hydraulic force servo control system. But the simple iteration learning exists in some questions such as the parameters choice of study law is aimless and the anti-interference of arithmetic need improve. Hence many robust control methods are combined with the conventional iteration learning method, such as adaptive control and variable structure control, which uses the robust setting ability for the system to avoid the aimless of study law parameters choice, and the open and closed loop combined with iteration learning control structure with feedback and feed forward action and H∞theory is adopted in the proposed method to design a robust iteration learning control law along with astringency and tracking ability, and a series of iteration learning law design method is proposed in this paper. The effectiveness of the every proposed iteration learning law is confirmed by using simulation and theory, which broadens the application domain and improves the practical applicability of iteration learning control.The main work in this paper:I) The characteristic and control require and control strategy and current research situation of application of electro-hydraulic force servo control system is summarized, then, the basic concept and idea of iteration is presented and the research and application results of iteration learning control is classify introduced and reviewed, and the convergence speed and tracking accuracy of improved arithmetic of iteration learning control technology is summarized, finally, the relative research background and significance of this project is explored and the main research work is presented.Ⅱ) The various modeling method for electro-hydraulic force servo control system is researched. The model research provides the theory base to analyze the nature characteristic of system and propose reasonable revise strategy. Then, the nonlinear characteristic of electric-hydraulic servo valve is analyzed, and the transfer function of valve controlling cylinder electro-hydraulic force servo system is established. Next, the state space model based on force variables and bias variables for electro-hydraulic force servo system are deduced, which can be used as the base of follow-up analysis. Finally, the hybrid simulation model of valve controlling cylinder electro-hydraulic force servo system is introduced, namely, the physical model and digital controller model of system is simulated by using the most close to the actual engineering simulation and modeling method.Ⅲ) Many intelligent robust iterative learning algorithms are researched, which is combined with adaptive control. In order to resolve these question such as original state excursion, uncertain and slow changing of non-modeling dynamic, and the aimless of study law parameters choice, the comprehensive open and close loop for the iterative learning control structure is adapted which has the feedback and feed forward action. The alone iterative learning algorithm has the drawback of poor antijamming capability, in order to realize the faster convergence of expected value during learning control process and resolve the effect of astringency and tracking performance during iterative learning control process, which is combined with variable structure control, and uses the H∞theory, and robust iterative learning control law due to the excellent astringency and tracking performance. The iterative learning algorithm became the practical control technology because of the two question is resolved.IV) The electro-hydraulic force servo control system is researched and the electro-hydraulic force servo characteristic is analyzed, the comprehensive open and close loop for the iterative learning control structure is adapted which has the feedback and feed forward action due to system model knows a little and a lot of system parameter is unknown. The reasonable structure controller is designed by using the convergence condition of theory analyses. The main question is that the unknown information induces the aimless learning parameter choice of electro-hydraulic force servo control system by using iterative learning control such as high order characteristic, original state excursion, non-modeling dynamic, and the changing of oil sources pressure and oil temperature, which is resolved in the paper.V) The control strategy of electro-hydraulic passive force servo system is researched and the electro-hydraulic passive force servo characteristic is analyzed, and the iterative learning and variable structure based on H∞theory is adapted to resolve these questions such as location interference of electro-hydraulic load simulator, the redundant force of load change, and the excepted value changing with time variation, etc. There are the location control interference during opposite vertex synergy and.the redundant force of external interference come from frictional force. Here, the drawback of weak anti-interference ability of alone iterative learning is the important question to improve the robustness. A reasonable structure controller is designed and the convergence condition is analyzed. The simulation results shows that the control strategy can remains the high accuracy tracking performance and improves the robustness and relaxes the convergence condition.VI) The DSPACE platform is used in the experimental research of electro-hydraulic force servo system, and the electro-hydraulic force servo driving force and double-cylinder electro-hydraulic passive force pilot system is established by using the actual physical model of hydraulic pressure and mechanical system and digital controller, and the hardware and software for experimental platform is designed. The rapid prototype test of every control strategy is realized by using the previous various controllers, and these questions of electro-hydraulic force servo system is improved, such as high order performance, nonlinear characteristic, uncertain parameters, load changing, expected values changing, and jamming-interference, and so on. The proposed strategy is proved to improve the rapidness, uncertainty, and robustness by using the real-time control experimental.
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