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Robust Control For Flexible Link Manipulator

Posted on:2019-10-31Degree:MasterType:Thesis
Country:ChinaCandidate:H GaoFull Text:PDF
GTID:2428330596950985Subject:Engineering
Abstract/Summary:PDF Full Text Request
With the development of material technology,the demand of all walks of life is tended to lightweight,fast,low energy consumption,high load,high precision of material structure,especially in industry robot.In the field of aerospace,industrial automation and intelligent manufacture,the flexible materials are widely used.Flexible manipulator is a typical representative of these applications,and it is widely concerned and studied in recent years.The flexible mechanical arm as a controlled object in control system is a class of nonlinear,strong coupling,time-varying,multiple input multiple output(MIMO)and unstable system,because of its flexible structure and complex movement characteristic.The two degree of freedom serial flexible manipulator(2DSFM)has been made into a modular experimental platform with low cost,which is an advantageous tool for studying the control algorithm of flexible structure.In this thesis,based on the 2DSFM developed by QUANSER in Canada,considering the modeling error and external disturbance of 2DSFM system,robust control algorithms are designed to achieve the trajectory tracking control of the flexible rod.The main contents are as follows:Firstly,based on the 2DSFM system structure and it's kinematics characteristics,2DSFM kinematics rules are considered and the 2DSFM system dynamics model is established.Secondly,the backstepping control is studied for 2DSFM system dynamics model,and it is applied to the trajectory tracking control of 2DSFM system.Considering the model is affected by the presence of parameter uncertainties and external disturbances caused by system operation,the extended state observer(ESO)has been studied.Regarding the external disturbances and parameter uncertainties as the augmented state,it is estimated and is applied to the controller design to compensate the external disturbances and parameter uncertainties,for increasing the robustness of the controller.Numerical simulations and experiments have proved that the designed backstepping control based on ESO can effectively track the expected signals,and has a certain inhibitory effect on the system chattering.The designed ESO can observe the unknown state of the system in real time,which indirectly verified that the augmented state of ESO can be used to compensate the uncertainties and external disturbances.Then,according to the dynamic model of 2DSFM system,considering the flexible structure of 2DSFM,a high order sliding mode control(HOSMC)method is studied.In this developed method,the switching of traditional sliding mode is hidden in the derivative of the control output,so that the control measure has a smooth output characteristic.HOSMC must exist high derivative of the system state,and this is unpredictable in the actual system.So,there adopt a robust differentiator to estimate the high derivative of the system state according to its low measurable state.The simulation results show that the designed HOSMC can realize the trajectory tracking target for 2DSFM and the control outputs are smoothing.Furthermore,the chattering of the system is greatly reduced.Finally,in view of the 2 DSFM system dynamics model,considering the above two kinds of robust control algorithms are need the information of the upper bound of the disturbance,which is difficult to obtain in the actual system.In such case an integral sliding mode control method based on disturbance observer(DOB)is studied.The designed DOB is mainly used to compensate the modeling error and external disturbance of system,meanwhile,the integral sliding mode controller is used to realize the trajectory tracking of 2DSFM.Numerical simulation shows that the robust controller can enable 2DSFM to track a given signal in case of there exist modeling error and unknown disturbance.
Keywords/Search Tags:2DSFM, nonlinear system, chattering, ESO, disturbance observer, trajectory tracking, robust control
PDF Full Text Request
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