Research On Nonlinear Robust Control Strategy Of Electro-hydraulic Servo System Considering Constraints

With the background of the Natural Science Foundation of China,in order to achieve high-precision position tracking of electro-hydraulic servo systems,this paper researches the advanced nonlinear robust control strategy with considering the physical constraints contained in actual electro-hydraulic servo systems(EHSS).The research mainly focuses on the following aspects:1.With consideration of constraints contained in EHSS,the nonlinear models of EHSS are constructed.There exists lots of model uncertainties in EHSS which are highly nonlinear.In this paper,in order to realize the high performance control of the EHSS,the physical constraints like saturation and input delay in EHSS,which influence the performance of the systems a lot,should be considered in the construction of the nonlinear system models.2.The control strategy of EHSS with consideration of saturation constraint.Most controllers often ignore the actual physical constraints of the system during the design process.However,once the saturation happens to the system,the control system performance will be deteriorated.In this paper,with consideration of saturation constraint and based on robust control strategy,a novel saturated robust control strategy is designed by using the quality of hyperbolic function.High performance of EHSS with lower conservation can be achieved by the controller,which indicates that the designed control strategy possesses more practical application value.3.The control strategy of EHSS with consideration of input delay constraint.The input delay exists in actual EHSS inevitably due to the influence of components.In order to achieve better control performance,a new control strategy is proposed in this paper.A delay compensation signal is introduced in the controller to obtain an open loop error system without input delay.The influence caused by input delay can be eliminated by using the Lyapunov-Krasovskii functional.In addition,the control scheme which considers both input delay and saturation is also developed to achieve high control performance of more general EHSS.4.The control strategy of overall high-precision position tracking of EHSS.The existing controllers typically cannot take into account both the steady-state and transient performance of the system at the same time.By referring to the adaptive robust control(ARC)strategy which possesses excellent transient performance and the robust integral of the sign of the error(RISE)control strategy which has excellent steady-state performance,a new control strategy is proposed,which achieves overall high-precision position tracking of the EHSS in the presence of external disturbances.5.The effectiveness and superiority of the proposed control strategies are verified via extensive comparative simulation by MATLAB/Simulink.