Research On Trajectory Tracking Control Method Of Cartesian Coordinate Robot

With the continuous rise of labor cost,the shortage of workers in laborintensive industries is becoming more and more serious.Robot,as an automatic and intelligent equipment,is widely used in industrial production.Cartesian coordinate robot occupies a large proportion in industrial production because of its simple structure and low price.The Cartesian coordinate robot mostly does repetitive point position and continuous motion,which has the characteristics of nonlinearity and strong coupling.In this paper,the robot dynamic model is established from the engineering point of view,and three different control methods are designed based on the second-order sliding mode to realize the robot trajectory tracking control.Firstly,the Cartesian coordinate robot is briefly introduced,and the modeling idea of Lagrange method is summarized.Through reasonable engineering simplification of the robot,the dynamics of the robot is modeled by Lagrange equation,which lays a foundation for the design and research of subsequent control methods.Aiming at the influence of parameter uncertainty and external disturbance,an improved second-order sliding mode control based on extended observer is designed.Based on the traditional super spiral algorithm,two functions are introduced to dynamically adjust the parameters of the algorithm,which better weakens the sliding mode chattering and improves the stability of the system.Compared with the traditional super spiral algorithm,the fast performance is improved.The extended observer can estimate the compound disturbance,and combine the two to track the robot.The tracking accuracy of the robot is improved,the robustness is superior,and the desired trajectory can be tracked quickly.Considering that the error will increase with the superposition of repetition times,an iterative learning second-order sliding mode control is designed.Iterative learning can well track the desired trajectory of the robot when it moves repeatedly.The second-order sliding mode learning law is adopted to continuously iterate the tracking error,which can not only reduce the robot tracking error,but also further suppress the influence of external disturbance on the system,improve the control accuracy and enhance the robustness of the system.Aiming at the contour error caused by the disharmony between robots in three-axis motion,an iterative learning second-order sliding mode cross coupling control is designed.The Newton extreme value algorithm is introduced to dynamically estimate the robot contour error,and the cross coupling controller is designed to obtain the error components of each axis.The error components are iteratively learned through iterative second-order sliding mode control,so as to reduce the contour error when the three axes move at the same time and make the robot have better tracking effect when the three axes move.