Continuous-time indirect adaptive control of the electrohydraulic servo systems

A continuous-time robust indirect adaptive control (IAC) algorithm with a self-excitation capability is proposed for position control of an electrohydraulic servo system subject to parametric uncertainties and load disturbances. In this algorithm, a gradient least squares dead zone estimation is used to identify the plant parameters and then a linear pole-placement controller is designed using the estimate. By a coprimeness verification procedure, the proposed algorithm facilitates the establishment of the adaptive pole-placement control of the closed-loop system by using an additional nonlinear feedback signal implemented for supplying the system with sufficiently rich signals. An analysis shows this algorithm can guarantee parameter estimation convergence and system stability based on the certainty equivalence principle. The performance of the proposed algorithm is evaluated through both the simulation results and the experimental studies. Simulations and experiments are conducted to see how well the proposed algorithm compares with two existing control schemes in controlling the same process. The results show that the IAC scheme confirms the analysis and has considerable robustness subject to parametric uncertainties and load disturbances and has better performance than the other two controllers.

[1]  P. Hartman.  Ordinary Differential Equations , 1965 .

[2]  Wolfgang Hahn,et al.  Stability of Motion , 1967 .

[3]  B. Porter,et al.  Performance characteristics of an adaptive hydraulic servo-mechanism† , 1970 .

[4]  Karl Johan Åström,et al.  Robustness of a design method based on assignment of poles and zeros , 1980 .

[5]  C. A. Desoer,et al.  Nonlinear Systems Analysis , 1978 .

[6]  H. Elliott.  Direct adaptive pole placement with application to nonminimum phase systems , 1981, 1981 20th IEEE Conference on Decision and Control including the Symposium on Adaptive Processes.

[7]  Hyungsuck Cho,et al.  Optimal open‐loop control of the mould filling process for injection moulding machines , 1983 .

[8]  M. M. Kulkarni,et al.  An Adaptive Control of an Electro-Hydraulic Position Control System , 1984, 1984 American Control Conference.

[9]  G. Goodwin,et al.  Persistency of excitation in the presence of possibly unbounded signals , 1985 .

[10]  Richard M. Johnstone,et al.  Global adaptive pole positioning , 1985, IEEE Transactions on Automatic Control.

[11]  Hyungsuck Cho,et al.  A Suboptimal Design Approach to the Ring Diameter Control for Ring Rolling Processes , 1985 .

[12]  R. Cristi,et al.  Global stability of adaptive pole placement algorithms , 1985 .

[13]  Karl Johan Åström,et al.  Simnon user's guide for MS-DOS computers , 1986 .

[14]  G. Kreisselmeier.  A Robust Indirect Adaptive Control Approach , 1986 .

[15]  G. Kreisselmeier,et al.  Stable adaptive regulation of arbitrary nth-order plants , 1986 .

[16]  R. M. H. Cheng,et al.  Investigation of an Electrohydraulic Servovalve With Tuneable Return Pressure and Drain Orifice , 1987 .

[17]  Hyungsuck Cho,et al.  Adaptive model following control of electrohydraulic velocity control systems subjected to unknown disturbances , 1988 .

[18]  Pramod P. Khargonekar,et al.  Toward Practical Adaptive Control , 1989, 1989 American Control Conference.

[19]  G. Kreisselmeier.  An indirect adaptive controller with a self-excitation capability , 1989 .

[20]  Karl Johan Åström,et al.  Adaptive Control , 1989, Embedded Digital Control with Microcontrollers.

[21]  Graham C. Goodwin,et al.  Digital control and estimation : a unified approach , 1990 .

[22]  Pramod P. Khargonekar,et al.  Parameter identification in the presence of non-parametric dynamic uncertainty , 1990, Autom..

[23]  Hyungsuck Cho,et al.  Application of an Adaptive Model Following Control Technique to a Hydraulic Servo System Subjected to Unknown Disturbances , 1991 .

[24]  H. E. Merritt,et al.  Hydraulic Control Systems , 1991 .

[25]  Mohammed M'Saad,et al.  On the robustness of discrete-time indirect adaptive (linear) controllers , 1988, Autom..

[26]  Pramod P. Khargonekar,et al.  A comparison of classical stochastic estimation and deterministic robust estimation , 1992 .

[27]  Bor-Sen Chen,et al.  A robust indirect adaptive regulation algorithm with self-excitation capability , 1993, IEEE Trans. Autom. Control..