Dynamics And Control Research Of High Speed Parallel Transplanting Robot In Greenhouse

The transplanting of seedlings in plugs of different densities is a key step in the greenhouse nursery industry.Transplanting efficiency is one of the problems that limit the scale of nursery.Existing greenhouse transplanters have low rigidity,poor precision,low automation,and are not flexible to plant which cannot meet current production needs.Based on the current research status,a new type of three-degree-of-freedom parallel transplanting robot has been developed to improve the efficiency of transplanting and the precision of its work.For this three-degree-of-freedom parallel transplant robot,the trajectory planning,kinematics,and dynamics were studied.The main contents are as follows:(1)Structural optimization of the transplant robot developed in the early stage of the research group and related parameter analysis of the physical characteristics of the seedlings.The degree of freedom and coupling degree of the optimized parallel transplanting robot are analyzed and the acceleration of the moving platform is simulated and compared with the help of ADAMS software to verify the rationality of structural optimization.The physical characteristics of seedlings include height,width and quality of seedlings,which provide parameter support for transplanting trajectory planning.(2)According to the improved working characteristics of the parallel robot,the transplanting trajectory is planned and kinematics and dynamics simulation analysis.The mathematical analysis software MATLAB was used to analyze the motion control function,and 3-4-5 polynomial functions were selected as the motion law control function of the moving platform.The virtual prototype model was established by Creo 3D modeling software.The simulation analysis of the virtual prototype was carried out with ADAMS simulation analysis software,including the kinematics simulation analysis of the platform speed,acceleration,etc.,verifying the correctness of the control function of the trajectory planning and dynamic platform motion law.(3)The dynamic model of the mechanism is established by means of Lagrange dynamics modeling method,and the rigid-flexible coupling dynamics analysis of the mechanism is performed.In the flexible module of ADAMS software,the easily deformable rods are discretized.Through the different loads on the moving platform,the change trends of the displacement,velocity and acceleration of the moving platform caused by the elastic deformation of the rods are analyzed.Contrast simulation analysis of the effects of two different transplanting trajectories on the torque,power,and angular velocity of the joints in the arc transition and the right angle transition provide the basis for controlling the selection of some motors.Based on PLC with motion control,design and hardware selection of control system.Then according to the column transplanting strategy,the individual transplanting process is programmed and the hole coo rdinates are assigned.(4)Based on the previous trajectory planning and simulation analysis,a parallel transplanting robot was used for the experimental study.The results showed that when the dynamic platform load is less than 1000 g,the error is small and the maximum acceleration is 30m/s 2.The transplanting efficiency is 1865 plants per hour,the transplanting success rate is about 95.3%.Through experiments,the stiffness of the system is a key factor that affects the success rate of transplanting.