Research On Backstepping Sliding Mode Control And Hardware-in-the-loop Simulation For Electro-hydraulic Servo Position System

Electro-hydraulic servo system is the driven part of the continuous cast mold positionsystem which has the law of non-sinusoidal vibration, thus the quality of slab can beimproved by ensuring the dynamic and static performance of this system. However, theexisting unavoidable impact of parameter uncertainties and external disturbance in theactual production applications makes the designing of the control system with highcapability difficult. So in this paper, we carry out the electro-hydraulic servo positionsystem driving continuous casting mold vibration as the research object and conduct thefollowing research aspects of its control system.Firstly, the mathematical model of the electro-hydraulic servo position system drivingcontinuous casting mold is derived based on its structure, working mechanism and actualtest, which is the fundation of the design of the controller with high capability and theresearch of hardware-in-the-loop-simulation.Secondly, considering the problems of unmeasurable states, parameter uncertaintiesand external disturbances in the electro-hydraulic servo position system, a backsteppingsliding mode control method is proposed. This method can estimate the states by using asliding mode observer. Then the controller is designed combining backstepping controland integral sliding mode. And adaptive fuzzy algorithm is used to approximate theunknown part of the designed controller. The stability of the system is proposed bychoosing appropriate Lyapunov functions. And the simulation results show that the systemhas well dynamic and static performance by using this method.Then, aiming at the problems of unmeasurable states, parameter uncertainties andexternal disturbances which exist in the electro-hydraulic servo position system, adynamic surface sliding mode control method is proposed based on the state observer.Proportion integral state observer is employed to estimate the system state efficiently.Then the controller is designed based on dynamic surface control and nonsingular terminalsliding mode to avoid “differential explosion” in traditional backsteppting design.Simultaneously, a kind of quasi potential function is introduced to improve the response speed and steady accuracy of the system. And the simulation results show that thedesigned controller can achieve accurate position tracking control of the electro-hydraulicservo position system.Finally, the mathematical model of the electro-hydraulic servo position systemdriving continuous casting mold is built by simulation circuit, using the CFCprogramming language to realise the dynamic surface sliding mode controller which isproposed previously, then control experiment of the electro-hydraulic servo system ismade due to the SIMATIC TDC. The results of the experiment show that the controlsystem can achieve the exact position tracking of the electro-hydraulic servo positionsystem, ensure that the system has strong robustness.