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Research On Robotic Manipulators Trajectory Tracking Control Strategy

Posted on:2019-01-06Degree:MasterType:Thesis
Country:ChinaCandidate:H Q LiangFull Text:PDF
GTID:2428330548967991Subject:Control theory and control engineering
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With the rapid development of science and technology,the robot manipulators has been widely used in various fields,and has imposed higher requirements on the accuracy and safety of its operation.The robot manipulators has flexible control methods and has a strong ability to adapt to the working environment.However,it is a complex and non-linear system and has a high requirement for the control system.Trajectory tracking is the basis for the follow-up work of the robot manipulators.Due to external disturbances,parameter uncertainties,and unmodeled dynamic effects,improving the accuracy of trajectory tracking and maintaining good dynamic and static performance of the robot manipulators are the key issues currently studied.Further study of the manipulator controller has important implications for improving the stability and safety of the system.Based on the study of the trajectory tracking control of the manipulator at home and abroad,the characteristics of the manipulator that is sensitive to external disturbances and the problem of chattering of the control system is studies in this thesis.Based on the disturbance observer(DOB),sliding mode control(SMC)strategy and nonlinear sliding mode control strategy with improved reaching law are designed.First,the spatial position description and basic transformation of the robot manipulator system are studied in depth.On this basis,the dynamic characteristics of the manipulator are analyzed in detail and the dynamical equation of the manipulator with N degrees of freedom is established using the Lagrange function,and a certain degree of simplification is made to establish a mathematical model.Secondly,DOB is introduced to overcome the influence of outside interference and non-modeling dynamics on the system,and a DOB-based robotic arm mathematical model is constructed.Among them,the observable part of the external disturbance is eliminated by DOB,and the unobservable part is compensated by the controller designed in this paper.For the system that requires fast response,an improved exponential reaching law is designed,an appropriate sliding surface is selected,the stability of the system is proved by Lyapunov function,and a corresponding control law is designed to realize compensation for unobserved interference.For systems with high control accuracy requirements,a nonlinear SMC strategy is used,a trajectory tracking error is defined using a DOB-based mathematical model,a nonlinear sliding surface is then designed,system stability is demonstrated,and a corresponding control law is designed.Finally,for the two controllers designed above,the trajectory tracking curves,trajectory tracking errors,and DOB observations are simulated.By comparing the simulation results of traditional SMC method,improved approaching law control method and nonlinear slidingmode control method,it is verified that DOB can reduce the influence of outside interference on the system.Sliding mode controllers and nonlinear sliding mode controllers that improve the reaching law can effectively reduce the system chattering and enhance the dynamic performance of the system.The former has a faster response speed,while the latter can maintain a smaller tracking error.
Keywords/Search Tags:Robotic manipulator, Tracking, Disturbance observer, Reaching law, Nonlinear sliding mode control
PDF Full Text Request
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