Research On Integration Technology Of Trajectory Tracking And Vibration Suppression For Delta High-Speed Parallel Robot

Delta parallel robots,characterized by their large stiffness and exceptional precision,are capable of conducting rapid material handling,packaging,and sorting operations.They have garnered significant attention in industries such as food,electronics,and pharmaceuticals.In recent years,with the escalating demand for enhanced production efficiency in modern industries,researchers have carried out a lot of research on the high-speed performance of Delta parallel robot,which has greatly improved its application prospect in the industrial field.However,the increasing running speed aggravates the vibration of the Delta parallel robot during operation,which in turn adversely affects its dynamic positioning accuracy and stability,and limits the application of the Delta parallel robot in high-precision scenarios to a certain extent.Consequently,this dissertation delves into the vibration suppression techniques for Delta high-speed parallel robots,encompassing kinematic and dynamic solutions,trajectory optimization,trajectory tracking control,and residual vibration control based on input shaping methods.By combining trajectory optimization and closed-loop input shaping,an integrated trajectory tracking and vibration control system is proposed,aiming to not only maintain production efficiency but also enhance the robot’s dynamic performance.The main research contents of this dissertation are as follows:(1)Modeling and analysis of the Delta high-speed parallel robot were conducted.The robot’s kinematic model was established utilizing geometric methods.Screw theory was employed to describe the interrelations among the robot components,and to determine the generalized actuating forces and generalized inertial forces of these components.With the integration of Kane’s equations,a simplified dynamic model of the Delta high-speed parallel robot was constructed.The accuracy of the kinematic model was validated by comparing MATLAB numerical calculations with motion simulation results from ADAMS.(2)Trajectory planning was undertaken for the Delta high-speed parallel robot,with multiobjective trajectory optimization being executed emphasizing both operational efficiency and stability.Initially,the NURBS curve was employed to fit the pick-up trajectory.Subsequently,the Improved Butterfly Optimization Algorithm(IBOA)was applied for multi-objective trajectory optimization.Within the IBOA,the Circle mapping was utilized to achieve a more uniformly distributed initial population,thus preventing the algorithm from falling into local optima.Moreover,the fractional-order differentiation technique was employed to enhance the convergence rate and accuracy of the original BOA.The convergence of the IBOA was analyzed using test functions and non-parametric testing methods,and it was juxtaposed against four other optimization algorithms.Simulation results highlighted the superior convergence rate and precision of the IBOA.Ultimately,the IBOA was harnessed for trajectory optimization targeting minimal time and impact.The simulation results show that,by using IBOA algorithm for trajectory optimization,the running time of the robot is shortened by 5.52 %,the inoperation impacts diminished by 79.2%,and the Root Mean Square(RMS)value of vibrational acceleration of the end-effector platform decreased by 14.5%,enhancing efficiency while effectively curtailing the vibration of the end-effector platform.(3)Effective trajectory tracking control is a crucial assurance for the optimal vibration suppression results of trajectory optimization.Based on the dynamic model of the Delta robot,the trajectory tracking strategy of the Delta high-speed parallel robot was investigated to cater to the rapid response requirements during high-speed operations.In this study,a predefinedtime nonsingular terminal sliding mode controller is proposed,wherein the improved nonsingular terminal sliding surface ensures that tracking errors converge to zero within a predefined timeframe.The Simulink model of the Delta high-speed parallel robot control system was constructed,and the tracking effect of the proposed predefined time nonsingular sliding mode controller is simulated and analyzed.The simulation results indicate that,compared to the fixed-time terminal sliding mode controller,the designed controller achieved tracking within a predefined time of 0.002 s,substantially enhancing tracking precision.(4)To suppress the residual vibrations of the Delta high-speed parallel robot during highspeed operations,this study integrates the optimal input shaper into the closed-loop of the control system,introducing a closed-loop optimal input shaping controller.Initially,modal analysis was conducted to identify the dominant modes impacting the residual vibrations of the end effector platform,from which the controller parameters were designed based on the dominant modal frequencies.Subsequently,a Smith predictor was employed to reduce the time delay associated with input shaping,and considering the system uncertainties,the closed-loop optimal input shaping controller was established.Simulation results demonstrate that the proposed closed-loop optimal input shaping controller outperforms other input shaping controllers in terms of vibration suppression.Finally,the control parameters were imported into ADAMS to analyze the vibration acceleration of the robot’s end platform.Compared to the approach without input shaping control,the investigated control strategy reduced the root mean square value of the end effector platform’s vibration acceleration by 44.9%.(5)To further enhance the dynamic performance of the robot and achieve superior vibration suppression results,an integrated control system for trajectory tracking and vibration suppression of the Delta high-speed parallel robot was developed by synthesizing trajectory tracking and input shaping techniques.An experimental platform for the motion control of the Delta high-speed parallel robot was established,encompassing a robot prototype,trajectory planning module,control module,and a state monitoring interface.The trajectory was generated by preset trajectory points,and the motion parameters after trajectory optimization were dispatched to the control module to drive the robot.At the meantime,the state monitoring interface enables real-time observation of the robot’s motion parameters and changes in acceleration of the end effector platform.Experiments involving trajectory tracking and integrated control were conducted on the physical prototype.Results demonstrated that,through adopting integrated control method,the variation range of the vibration acceleration of the robot’s end effector platform was reduced by 63.4%,effectively enhancing the robot’s dynamic performance during high-speed operations.