Research On Control Strategies For Vertical Electro-hydraulic Coupled Position And Force System

The vertical electro-hydraulic coupled force and position control system is mainly used to study the interference effect of another coupling system on the object under the position control or force loading control,which has great significance on improving the tracking performance of the electro-hydraulic system.Hence,supported by the National Natural Science Foundation of China Project “Research on coordination control of super-redundant electro-hydraulic system subject to vibration and force loading”(item number: 51575511),this thesis researchs on the vertical electro-hydraulic coupled force and position control system is carried out.First of all,this paper makes a kinematic analysis based on the structure of the electro-hydraulic system,so that the system can be independently controlled for each degree of freedom.On this basis,a mathematical model of the hydraulic system is set up,and the dynamic characteristics of the system are analyzed by the construction of the simulation model.Secondly,according to the coupling of force and position for electro-hydraulic system,the nonlinear control strategy is proposed.The design of backstepping controller is carried out according to established position and force loading state equation,and the simulation of the controller is carried out.Considering the coupling of force and position,when under the simulation of position system,the force signal is act on the system while the position signal is under control.When the force loading signal is under control,the position signal is act on the force loading system.The simulation analysis is carried out in the two cases respectively.Then,in order to further eliminate the disturbance caused by the coupled system,the adaptive robust controller is proposed on the basis of the designed backstepping controller.For position system,the disturbance observer and parameter adaptive method are used to improve the performance of controller.For the force loading system,adaptive backstepping sliding mode control is applied to improve the performance of controller.The two controllers are simulated to verify the control effect of the proposed adaptive robust controller.Finally,the working principle of the testing system and the composition of the hardware and software are introduced,then the experimental verification of the coupling of force and position for electro-hydraulic system is carried out.On traditional controller,backstepping controller and adaptive robust controllerexperiment,the specific approach is to apply disturbance which is from coupled force loading system to position system,apply disturbance which is from coupled position system to force loading system.The tracking accuracy of the final output signals are compared to verify the effectiveness of the proposed control strategy.