节选外文翻译--对采用进化策略优化电液伺服系统的控制器增益的实验性研究(编辑修改稿)

节选外文翻译--对采用进化策略优化电液伺服系统的控制器增益的实验性研究(编辑修改稿)内容摘要：

ce. paring with the Proportional plus integral plus derivative (PID) controller, the state feedback controller, or adaptive controller, the structure of this controller is as simple as the PID controller, because it does not require a realtime estimation of state variables or system parameters using observers, nor does it a putation of inverse system dynamics. Recently, a research has been performed on a fluid power system using a TDC by Chin, Lee, and Chang (1994). The application results show easiness of the real implementation of this controller and robustness on various uncertainties of the plant. For the hydraulic system shown in Fig. 1, a study on For the hydraulic system shown in Fig. 1, a study on (1998). He designed a 2nd order TDC with simplification of the nonlinear system dynamics of 5th order through theoretic analyses on this system, proved the global stability of the internal dynamics (‘‘unobservable’’ part except input–output part in system dynamics) through the inputoutput linearization technique, and proposed the region of stability for closedloop system. shows a control block diagram of the electrohydraulic position control system with a TDC controller, where s is variable of Laplace transform and L is sampling time. The controller is embodied with the three controller gains (E to be system constant, n and  to decide on error dynamics of the system) in block diagram as shown in the following equation: )()()}()(2)({)( 2 LtXELtUtetetXEtU nnd    . Theoretic settings on TDC gains and practical problems In general, the gain setting method for TDC is as follows: theoretically the controller gains of TDC are not necessary to be tuned. For instance, let us consider a case in which a TDC of 2nd order is designed like Eq. (1). First by setting the values of n and  to define the error dynamics of system, poles of the 2nd order system can be determined. Then, the frequency responses of system is decided on by specific poles. Secondly the value of E to be system constant is specified to be in the region of stability for the stability of the closedloop system. Namely, according to the desired control specifications, the value of n and  can be selected, and the value of E can be tuned as close as possible to a limit of the region of stability (YoucefToumi amp。 Ito, 1990). However, when a TDC is applied to real system, the setting of controller gains on the TDC has several problems. First, when a reference input is given, it is some practical problem how the locations of poles will be assigned. Furthermore though a trajectory is determined in the form of reference model for following the reference input, the ability of the system for following the trajectory is unknown before the controller is applied to real system (Chin et al., 1994). Secondly the value of E is related to the inertia of the system. In real system, the estimation of the system inertia is another hard problem. The error between the system constant and the estimated E directly affects the error dynamics of the closedloop system, so it bees a reason why the system does not follow the prescribed reference model with accuracy (YoucefToumi amp。 Reddy, 1992). Thirdly the saturation of actuators or a controller, the friction characteristics of the system, etc. are able to bee causes to obstruct the trajectory following (Chang amp。 Park, 2020). The results of the experiments with the theoretical settings of the TDC controller gains were as follows. Because of the pressibility of the working fluid excluded to simplify the system modeling, it is necessary that the damping ratio of the reference model is designed to be overdamped ( 1). It is very difficult to determine proper n and  due to the friction characteristics on the hydraulic system—the friction of hydraulic actuator is generally larger than other actuators. Though the controller gains are tuned for the system to have some satisfied performance via the above mentioned procedures, it is uncertain that they are the optimal gains under a given performance index. Hence, in the case of the real system, the optimal controller gains of TDC can be searched and settled in the given gain regions via the proposed ESbased method. diagram of the position control system with a time delay controller. 3. Evolution strategies Since ESs had been developed for solving experimental optimization problems applied to hydrodynamics, they have been successfully applied to va。