Robotic end effector for handling greenhouse plant material.
ABSTRACT An end effector was developed to investigate the mechanics and control of robotic handling and manipulation of plant material of a type commonly found in commercial greenhouses. The end effector was shown to handle a wide range of sizes of geranium cuttings with rare indications of damage to the petioles (1.5%) and main stem (2.0%). Several features of the end effector were determined to be important for reliable, non-damaging performance. A two-stage feedback controller which combined position/velocity control with force control was successful in minimizing cycle time while also minimizing impact velocity and resultant impact loads on plant material. A machine vision local scene analysis technique provided an automatic method of obstacle avoidance by the fingers in a plant canopy. Padded fingers with relatively small, curved ends minimized contact area and assisted in decreasing impact forces. In general, results indicate the importance of sensing and interpretation of the sensor data to assist a robot in accommodating the nonuniformity typical of plants.