scholarly journals Simplified Adaptive Robust Motion Control with Varying Boundary Discontinuous Projection of Hydraulic Actuator

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Cungui Yu ◽  
Xianwei Qi

This paper deals with the high performance adaptive robust motion control of electrohydraulic servo system driven by dual vane hydraulic rotary actuator. The recently developed adaptive robust control theory is used to handle the nonlinearities and modelling uncertainties in hydraulic systems. Aside from the difficulty of handling parametric variations, the traditional adaptive robust controller (ARC) is also a little complicated in practice. To address these challenging issues, a simplified adaptive robust control with varying boundary discontinuous projection is developed to enhance the robustness of the closed-loop system, based on the features of hydraulic rotary actuator. Compared with previous ARC controller, the resulting controller has a simple algorithm for more suitable implementation and can handle parametric variations via nonlinear robust design. The controller theoretically achieves a guaranteed transient performance and final tracking accuracy in the presence of both parametric uncertainties and uncertain nonlinearities. Extensive simulation results are obtained for a hydraulic rotary actuator to verify the high performance nature of proposed control strategy.

Author(s):  
Z. B. Xu ◽  
J. Y. Yao ◽  
Z. L. Dong ◽  
Y. Zheng

In this paper, an adaptive robust control for hydraulic actuators with disturbance estimation is proposed for a hydraulic system with mismatched generalized uncertainties (e.g., parameter derivations, external disturbances, and/or unmodeled dynamics), in which a finite time disturbance observer and an adaptive robust controller are synthesized via backstepping method. The finite time disturbance observer is designed to estimate the mismatched generalized uncertainties. The adaptive robust controller is designed to handle parametric uncertainties and stabilize the closed loop system. The proposed controller accounts for not only the parametric uncertainties, but also the mismatched generalized uncertainties. Furthermore, the controller theoretically guarantees a prescribed tracking transient performance and final tracking accuracy while achieving asymptotic tracking performance after a finite time T0, which is very important for high accuracy tracking control of hydraulic servo systems. Simulation results are obtained to verify the high performance nature of the proposed control strategy.


Author(s):  
Hamed Moradi ◽  
Kambiz Haji Hajikolaei ◽  
Firooz Bakhtiari-Nejad

Due to the nonlinear dynamics of hydraulic systems, applying high performance closed-loop controllers is complicated. In this paper, a single-rod hydraulic actuator is considered in which load displacement (for positioning purposes) is controlled via manipulation of the input voltage to the servo-valve. Dynamics of the servo-valve is described by first and second order transfer functions (named as Models 1 and 2). Through linearization of the system around its operating points, dynamics of the hydraulic actuator is represented in the state space. A full-order observer is designed for on-line states estimation. Then, feedback control system is designed for both regulation and tracking objectives through pole-placement approach based on general canonical control form (GCCF). For tracking of the desired commands, a modified integral control is required (since the plant has not integrator). Results show that the regulation, states estimation, desired tracking and final tracking accuracy are achieved after applying the controller. Required input voltage and load positioning are compared for the two distinct dynamics of the servo-valve (Model 1 and 2).


Author(s):  
Bobo Helian ◽  
Zheng Chen ◽  
Bin Yao ◽  
Yi Yan ◽  
Chiang Lee

Pump control hydraulic systems have been widely used in industry by the advantages of no throttling loss and overflow loss as well as high power-to-volume ratio. However, the characteristics of high order dynamics, high nonlinearities and disturbances make the accurate position control of those systems very challenging. And to implement the controllers easily, some dynamics such as servo motor loop are usually ignored in most of existing methods, which may lead to the limitation of closed-loop bandwidth and disturbance rejection ability. In this paper, adaptive robust control (ARC) algorithm is utilized in a pump control electro-hydrualic system. The ARC guarantees the stability and high performance in the presence of model uncertainties and nonlinear disturbances. For the high-order of the hydraulic system, a modified three-step backstepping method is constructed which is covering the whole electro-hydraulic system. The servo motor-pump dynamics is taken into considered in the three-step adaptive backstepping controller design. Theoretical control performance based on Lyapunov functions and the simulation results proved that the control strategy this paper proposed achieved high performance in spite of the nonlinearities and uncertainties.


Author(s):  
Janne Koivumäki ◽  
Jouni Mattila

In order to achieve higher energy efficiency for hydraulic systems the Load Sensing (LS) systems, i.e. a Variable Displacement Pump (VDP) with hydro-mechanical control system, can be considered as a state-of-the-art solution. However, as is well known, these traditional hydraulic LS-systems are usually characterized by difficulties in tuning, which can lead to system stability problems. In our previous studies, we have developed a high precision motion control for hydraulic manipulators with separate meter-in meter-out controlled hydraulic actuators. Our control approach was based on the Virtual Decomposition Control (VDC) approach that ensured high motion tracking performance while rigorously guaranteeing the system stability. In this paper, we propose both energy-efficient and high performance nonlinear model based motion control scheme that utilizes the developed servocontrolled Electric Load Sensing (ELS) system for hydraulic robotic manipulators. Experimental results are presented with the proposed ELS-controlled VDP and hydraulic manipulator lifting servoactuator that utilized a separate meter-in meter-out flow control scheme.


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