Integral Adaptive Sliding Mode Control Of Fruit Clusters Sorting Parallel Robot Based On On-line Identification Of Rotational Inertia

A significant role in world agricultural production in China,is one of the major agricultural producers in the world.With the development of agricultural modernization,the requirements for automatic sorting technology of agricultural products are constantly increasing.Therefore,based on the potential excellent performance of parallel mechanism with strong bearing capacity,high stiffness and high control precision,this research group developed a parallel robot for fruit sorting that can realize SCARA movement.Cluster fruits such as litchi and grape are difficult to realize automatic sorting due to their different shapes and sizes and close stacking of fruit grains.This paper focuses on the study of cluster fruit sorting control of parallel robot.As for the control of parallel robot for fruit sorting in tandem,the current research difficulties are as follows:the parallel robot has uncertainty problems such as time varying model parameters and external disturbance.In addition,the sorting load of parallel robot for fruit sorting in tandem is unknown and dynamically changing,especially when the fruit string is involved,the moment of inertia of load will change greatly.Therefore,in this paper,aiming at the parallel robot of fruit sorting series,an online identification method of the moment of inertia of a large range of varying loads is proposed and a branch chain motor model of the parallel robot is established.Then,an integral adaptive sliding mode control method is proposed to improve the control performance of the parallel robot of fruit sorting series and suppress chattering under sliding mode control.The main work of this paper is as follows:(1)The kinematics and dynamics of parallel robot for fruit sorting were analyzed.Through the kinematics analysis,the inverse kinematics solution of the mechanism is obtained,and the kinematics characteristics of the parallel robot are analyzed.The virtual work princi ple method is used to analyze the dynamic characteristics of the fruit clusters sorting parallel robot,so as to lay the foundation for establishing a single branch chain motor model with online identification of a wide range of load rotational inertia.(2)An adaptive sliding mode control method based on integrated moment of inertia of a parallel fruit-sorting robot is proposed for on-line identification of a large range of varying loads.In order to solve the problem that the sorting load of parallel robot for parallel fruit sorting is unknown and dynamic,especially when the fruit string is involved,the moment of inertia of the load will change greatly,which will affect the robustness of the control system.Based on the analysis of the mechanical motion equation of AC servo motor,the gradient correction parameter identification algorithm is adopted to identify the moment of inertia of a large range of varying loads online.Then the branch chain motor model is established.In order to improve the robustness of the control system of parallel fruit-sorting robot in parallel series and solve the problem that the uncertain upper bound is difficult to obtain,a sliding mode control method is introduced based on the branch chain motor model which identifies the moment of inertia of a large range of load online,and an integral adaptive law is designed to adjust the sliding mode switching gain quickly and effectively on the near sliding mode surface,thus improving the robustness of the system.The chattering is effectively inhibited by sliding mode control.Complete the stability theory proof,and carry out the MATLAB simulation experiment.The simulation is compared with the integral adaptive sliding mode control which does not consider the on-line identification of the moment of inertia of the large range varying load to verify the necessity of on-line identification of the moment of inertia of the large range varying load.MATLAB simulation is carried out to verify that the proposed control method has better trajectory tracking performance and can effectively suppress chattering of sliding mode control considering the on-line identification of the moment of inertia of a large range of varying loads.(3)The experimental platform of parallel robot control system for fruit sorting was constructed and the prototype was verified.VC++6.0 is used to develop the upper computer program of parallel robot system for fruit sorting,and Pewin32Pro2 is used to develop the lower computer motion program of parallel robot for fruit sorting.Based on the experimental platform of the parallel robot control system for parallel fruit sorting,the motion control experiment of the parallel robot prototype for parallel fruit sorting was carried out to verify the superiority of the proposed control method.