Kinematics and Dynamics of a Fruit Picking Robotic Manipulator

Abstract. Fruit harvesting is widely done by hand. But labor availability and cost is a major problem in many countries. Accordingly, there have been many studies attempting to develop robotic fruit harvesting. Many of these studies utilize manipulators with an end effector to grasp and detach the fruit, at least six degrees of freedom, and at least three rotational joints connecting neighboring links to cover the workspace. Further research is needed to develop practical and economical technologies.

 Initially, this work starts with the common Puma 560 robot arm. Forward and reverse kinematics and dynamic analyses are performed using the MATLAB Robotics Toolbox. The kinematics analyses study the positions of the end effector and the dynamic analyses study the needed joint torques. The joint angles, velocities, and torques as a function of time are studied during example pick cycles which span the workspace of representative peach and orange trees.

 The development of the best fruit picking manipulators will depend largely on the tree size and the fruit distribution within that tree. An arm designer graphical user interface (GUI) is introduced and demonstrated which can analyze different arm lengths and base heights for manipulators similar in structure to the Puma 560. Kinematic and dynamic analyses are integrated into the GUI, which helps the user of the GUI understand the picking performance of the generated arm. The use of it to study the relationships between given fruit locations and the resulting needed arm dimensions and joint torques is demonstrated.