Robot workcell for transplanting of seedlings. Part I. Layout and materials flow

The transplanting of seedlings from high density plug trays into low density growing flats, as currently practiced in the bedding plant production systems, was the operation studied within a prototype workcell utilizing a Selective Compliance Assembly Robot Arm (SCARA) type robot. The concept of a multi-stop local work trajectory surrounding each seedling was incorporated into the workcell design consideration. The trays and flats were envisioned to flow across each other's path at different heights within the workcell. A straight-line robot wrist motion was used between the locations on a tray and a flat. A computer program for checking the interactions of the workcell layout, the robot motions and the flows of materials was developed. The average robot wrist horizontal travel distance per transplanting (AHT) for a given workcell could be readily calculated using this computer program. The AHT was evaluated for its use as an indication of the performance of any given workcell design. For the 12 cases studied, the AHT ranged from 0.381 m to 0.993 m which was found to correlate well with the average cycle time per transplanting.