Abstract:To address the issues of high labor intensity andlow work efficiency for the transfer of agricultural products from harvesting place to warehouse or transportation vehicle in the agricultural field, a material handling robot was designed, which enabled the robot to perform tasks such as grabbing, transporting, and placing materials. Aiming at the problem that the moving track and the working track were relatively independent and time-consuming when the material handling robot moved and grabed simultaneously, a time-optimal trajectory planning methodology for the cooperative working of the designed material handling robot was proposed, which can obtain the time-optimal trajectory for the simultaneous performance of the robot driving and grasping operation. This methodology was used to conduct the time-optimal trajectory planning for the material handling robot, which allowed to take into account the robot's kinematic and dynamic constraints of both the operation system and the driving system. Additionally, a control law was designed based on Lyapunov theory to reduce the error for the robot's path tracking and improve the accuracy and stability of the robot's trajectory tracking. Finally, the effectiveness of the time-optimal trajectory planning method for collaborative operation was verified through joint simulation by the co-simulation in Matlab/Simulink and ADAMS. The results showed that the proposed methodology can enable the robot to obtain a smooth and time-optimal motion trajectory during the material handling process, the displacement, velocity, acceleration, and force/torque of the operation system, and the tractive force curves of each joint of the robot changed gently, and the two-track tractive force met the requirements of the robot which can quickly and stably track the time-optimal path. The designed material handling robot and the proposed time-optimal trajectory planning methodology can provide an effective technical solution for the transfer of agricultural products in the agricultural field.
