Research On The Control Method Of 3-Dof DELTA Robot

DELTA robots have the advantages of high rigidity,fast moving speed and high precision,and are widely used in food processing,parallel machine tools and electronic assembly.However,in the application process,DELTA robots will have a series of problems due to the friction of the members and external disturbances.The control problem of repeated positioning accuracy has been a research hotspot.Through the design of the sliding mode controller,this paper realizes the effective control of the repeated positioning accuracy of the DELTA robot,and provides a reference scheme for the high precision application of the DELTA robot.Firstly,the whole structure of DELTA robot is analyzed,the target DELTA mechanism is designed,the constraint relationship of the robot bar is clarified,the kinematics model is constructed,the derivation of the positive and inverse numerical solutions of the target mechanism is completed,and the attitude diagram of all solutions is analyzed.The unique solution of the motion is determined,and the kinematics equation of the target robot is realized.Through the simulation study,the rationality of the model and the correctness of the equation are verified.First-order and second-order derivation of the motion displacement equation,the Jacobian matrix is obtained,and the relationship between the driving joint angle and the end position,velocity and acceleration is obtained.Secondly,the three dynamic modeling methods are compared and studied.Based on the structural characteristics of the target DELTA robot,the dynamic model of the target is established by the principle of virtual work.The mass matrix of the target robot's active arm,the follower arm and the moving platform is completed,and the kinetic energy relationship of the mechanism is used.The mass of the slave arm is equivalent to 1:2 to the moving platform and the active arm,simplifying the dynamic model and establishing The virtual work dynamics equation of the DELTA robot.Finally,a sliding mode controller is designed based on the dynamic model.The theoretical basis of sliding mode variable structure control is studied.For the chattering phenomenon of sliding mode variable structure control,the exponential approach law is used to weaken the processing.The sliding mode controller model based on dynamic equations is designed by selecting the appropriate sliding surface and defining the exponential approach law.Through simulation research,the influence of disturbance and member wear on the trajectory is analyzed,and the effectiveness of the sliding mode controller for improving the control precision of the DELTA robot is verified.