Research On The Tea Picking Robot Based On SCARA Manipulators

Tea picking is an extremely arduous task.There are mainly two types to pick tea currently:the one is manual picking and the other is mechanical picking.The labor demand for manual picking is large and it often faces the problem of labor shortage in the peak season.The existing tea picking machines are mainly for bulk tea picking,which are lack of selectivity.With the continuous development of robot technology and artificial intelligence,researches on the intelligent robot for famous tea picking have attracted more and more attention.Aiming at the automatic picking for famous tea,a new scheme of the tea picking robot based on SCARA manipulators is proposed in this dissertation.The purposes are to improve the efficiency and quality of tea picking and to improve the trajectory tracking performance.The main research contents of this dissertation include the following three aspects:(1)The modeling and analysis of the SCARA picking manipulator are carried out.Firstly,by using the D-H parameter method and the analytical method,the forward and reverse kinematic models of the specific SCARA picking manipulator are established.Then,based on the MATLAB platform and the ADAMS platform,the size of the ma-nipulator’s picking workspace is analyzed by using the Monte Carlo method.The simu-lation results show that the actual movement space of the SCARA picking manipulator virtual prototype is consistent with the theoretical analysis,which provides a theoretical basis for the system design of the tea picking robot and has important reference value for the spatial layout of multiple SCARA picking manipulators in the tea picking robot.(2)The motion control research of the SCARA picking manipulator is carried out.Firstly,by analyzing the methods and characteristics of tea picking,the starting point of the motion and the first tea point to be picked in the workspace are chosen.And the tea picking trajectories of each joint are planned by the fifth-degree polynomial interpola-tion method.Secondly,an adaptive robust PD controller is designed to compensate the unknown time-varying environmental disturbance and the uncertainties existing in the manipulator.Then,the controller is also used to control the end of the picking manip-ulator to reach the target tea position accurately.And based on Lyapunov theorem,the system stability under the controller is analyzed.Finally,co-simulations based on the MATLAB/Simulink platform and the ADAMS platform are performed,which are used to verify the effectiveness and stability of this controller in the practical application of the SCARA picking manipulator.The simulation results show that the designed trajec-tory tracking controller can ensure the smooth movement of the joints of the SCARA picking manipulator without vibration and shock.And the trajectory tracking error is small.(3)The system design of the tea picking robot based on SCARA picking manipu-lators is performed.Considering the overall performance of the intelligent tea picking robot and the specific tea garden application scenario,a novel system design scheme of the tea picking robot based on SCARA picking manipulators is proposed.Its me-chanical system integrates a four-wheel-driven walking mechanism,a tea bud combing mechanism,a tea picking mechanism,a tea collection device and an auxiliary lighting device,etc.Multiple inverted SCARA manipulators are used to pick tea leaves in par-allel to improve the picking efficiency.The end effector is designed as a chute-lever structure and the picking force at the fingertips is analyzed to ensure the integrity of the tea buds.Finally,the NX UG software is used to establish the three-dimensional model of the system,which lays the foundation for the platform construction of the tea picking robot.