Research On Vibration Suppression Control Of Flexible Robotic Arm With Hybrid Structure

With the rapid improvement of industrial automation level,the demand for flexible robotic arm is gradually growing in various industries because of its small weight,long arm span,good flexibility,large load,low cost and other characteristics.At present,flexible robotic arm has a wide range of applications in aerospace,engineering construction,emergency rescue and so on.Therefore,a large number of experts and scholars have conducted a lot of research on the technology related to flexible robotic arms.However,most of the current research results focus on single-linked flexible robotic arm or multi-linked flexible robotic arm,and there is less research on flexible robotic arm with telescopic structure,especially the research on flexible robotic arm which also contains the hybrid structure of rotation and telescoping is less involved.However,in practical applications,the hybrid flexible robotic arm with both rotating and telescoping joints has a greater range of activities and higher flexibility than the flexible robotic arm with only rotating joints or only telescoping joints.Therefore,the study of hybrid flexible robotic arm has more important practical significance and value.In this thesis,a hybrid flexible robotic arm with a rotary joint and a telescopic joint,which is nested by two connecting rods,is studied for its modeling and control method.The main research work includes the following parts.(1)In order to reduce the complexity of the system model,a method is adopted to model the system state variables separately by decomposing them rigidly and flexibly,which is not easy to solve because of the many state variables and high coupling degree of the hybrid flexible robotic arm system.In the modeling process,the system structure is divided into fixed section,overlapping section and extension section to establish the coordinate system according to the structural characteristics of the hybrid structure flexible robot arm with nested connecting rods,and the model analysis is carried out separately.For the modeling of the rigid structure,the rigid body Lagrangian equilibrium equation method is used to derive the dynamics model,and for the modeling of the flexible structure,the system model is simplified to the Euler-Bernoulli beam model for analysis,and the elastic deformation of the beam is described by the hypothetical modal method,and the dynamics equation is derived according to the Lagrangian equation.Among them,the flexible dynamics equation is a linear time-varying system with the coefficient matrix as a function of the state variables of the rigid structure,which effectively reduces the difficulty of system control.(2)For the trajectory tracking control problem of the hybrid structure flexible robotic arm,a sliding mode variable structure control method is used to design the control law to realize the fast tracking of the rigid structure partial model,and the motion trajectory of the state variable of the flexible structure partial dynamics equation is obtained by substituting the rigid structure state variable into the flexible structure partial model.In addition,for the chattering phenomenon in the tracking process,the chattering is effectively suppressed and the control performance is improved by replacing the sign function with the saturation function.(3)For the problem that the state variables of the flexible structure become larger during the trajectory tracking process,the output constraint is realized by combining the Barrier Lyapunov function with the backstepping method,and the vibration of the partial modal variables of the flexible structure is within a reasonable range.In this thesis,the modeling and control methods are studied for a hybrid nested structure flexible robotic arm containing both a rotary joint and a telescopic joint.The system is modeled using the idea of rigid-flexible separation,and the dynamics equations of the rigid structure part and the flexible structure part are established respectively.The output of some state variables of the flexible dynamics equations are constrained during the trajectory tracking control process,and the state variables are verified to be within a reasonable range through simulation experiments,thus the rationality of the proposed model is illustrated.