Motion Planning and Test of Robot for Seedling Tray Handling in Narrow Space

Abstract

Due to the high cost of plant factory, we put forward a logistics handling robot, worked in a wide range but took up a narrow space when in non working state, based on plant factory. First, we introduced its work environment and task characteristics. The space, which the robot takes up, needs to be minimized as far as possible, what’s more, the optimal trajectory must ensure that the distance between the robot and the seeding platform reaches the minimum. Then, we adopted D-H method to establish the connecting rod coordinate system, and analyzed the robot movement space through solving the kinematics equation. On this basis, we planned a kind of sliding handling optimal trajectory to meet the vertical cultivation characteristics of plant factory. Then, we extracted some points on the trajectory and solved the kinematics inverse solution of those points. Next, we fitted time varying function curve of manipulator’s joint variable by using cubic spline interpolation. Last, we made a test machine and set up a vertical seedling platform in the lab. We controlled the robot to move along the optimal trajectory with a high speed camera recording its actual moving tracking. The test showed that the maximum absolute deviation of actual moving tracking was 8mm which was within the error range and verified the correctness of the inverse solution. So the invention can complete the needed handling work and provide a good platform for the following study of plant factory.

Keywords: plant factory, handling robot, seedling management, narrow spac, trajectory planning