Research On Picking Posture And Sequence Of Citrus Picking Robot

Citrus is one of the large-scale cultivated agricultural products in Chongqing and even in the Southwest,and is an important pillar of agricultural economic development.At present,citrus picking is mainly based on artificial methods,which has the disadvantages of concentrated picking operations,high labor intensity,high cost,and low efficiency.Therefore,researching intelligent and efficient citrus picking robots can help reduce labor intensity,reduce production costs,and increase productivity.Picking posture and picking sequence directly affect picking robot's picking success rate,efficiency and energy consumption.For this purpose,the following research has been carried out in these two aspects:(1)The forward kinematics and inverse kinematics of citrus picking robot are solved;the simulation interface of forward kinematics and inverse kinematics solution is designed,and the robot state simulation diagram corresponding to positive and inverse kinematics solutions and different inverse solutions can be visually observed;the Monte Carlo method was used to simulate and analyze the working space of the robot.According to the characteristics of the work space,the coordinates of the citrus center point in the picking space were selected and picked.(2)For the natural environment,it is difficult to obtain spatial position information of citrus stems through the visual system,resulting in the lack of robot picking posture and affecting the success rate of picking.Based on the actual growth of citrus stems and the occlusion type end-effector by the research group,this paper established the model of the end-effector picking the citrus.The objective function of picking posture of the citrus picking robot was proposed and solved.In order to complete the task of picking the robot according to the desired picking attitude,a Cartesian space trajectory planning method with five polynomial and linear functions fitting is proposed and verified by simulation.The simulation results show that the velocity curve of the trajectory planning method proposed in this paper is smoother and can effectively solve the problem of abrupt acceleration of the picking robot in the start and stop phases.(3)Combining the operation requirements of the citrus picking robot to continuously pick multiple citrus,a new picking sequence planning method and intelligent optimization algorithm are proposed based on the existing picking sequence planning method,and the selection of inverse solutions and sorting in the dynamic programming is realized.The simulation results show that using the new picking sequence planning method,the energy consumption during the picking process is smaller;the proposed intelligent optimization algorithm can effectively perform inverse picking and sorting of multiple picking citrus.(4)An experimental platform for citrus picking robots was set up.Indoor and outdoor citrus picking experiments were conducted.The results show that the Cartesian space linear trajectory planning method proposed in this paper can meet the requirements of the robot's indoor and outdoor environment on the picking path and picking posture;the success rate of the picking robot end-effector containing citrus in the indoor and outdoor environment are 89.47% and 70.00% respectively;The "minimum energy consumption" planning method and “the double intelligent optimization algorithm” proposed in this paper can achieve the multi-fruit continuous picking function of the picking robot,compared to the multi-fruit picking algorithm based on the “shortest path” principle,the average energy consumption was reduced 16.20%.Compared to “minimum energy consumption” principle that only considering multi-fruit picking sequence without considering inverse solution selection,the average energy consumption was reduced 12.62%.