Robotic systems, methods, and end-effectors for harvesting produce

Abstract

Robotic systems and specialized end-effectors provide for automated harvesting of produce such as fresh market apples. An underactuated design using tendons and flexure joints with passive compliance increases robustness to position error, overcoming a significant limitation of previous fruit harvesting end-effectors. Some devices use open-loop control, provide a shape-adaptive grasp, and produce contact forces similar to those used during optimal hand picking patterns. Other benefits include relatively low weight, low cost, and simplicity.

1 - 25 . (canceled) 
     
     
         26 . A robotic produce harvesting system, comprising:
 an end-effector comprising
 a plurality of fingers which are tendon-driven, and 
 a plurality of actuators configured for independent actuation of the plurality of fingers, 
 wherein the end-effector is underactuated, and 
 wherein the end-effector is configured to grasp a piece of produce to be harvested with a power grasp; 
   a manipulator for positioning the end-effector in three-dimensional space; and   a machine vision system for providing a location of the piece of produce to be harvested.   
     
     
         27 . The system of  claim 26 , wherein the manipulator is configured to execute planned trajectories using a look-and-move approach. 
     
     
         28 . The system of  claim 26 , wherein the end-effector has a passive, adaptive grasp. 
     
     
         29 . The system of  claim 26 , wherein the end-effector utilizes open-loop, feedforward control. 
     
     
         30 . The system of  claim 26 , wherein the end-effector is configured to grasp a piece of produce selected from apples, tomatoes, lemons, grapefruits, and oranges. 
     
     
         31 . The system of  claim 26 , wherein the plurality of fingers comprises three or more primary fingers. 
     
     
         32 . The system of  claim 31 , wherein the end-effector further comprises a palm. 
     
     
         33 . The system of  claim 32 , wherein the primary fingers are arranged symmetrically about the palm. 
     
     
         34 . The system of  claim 26 , wherein the manipulator and end-effector are configured to move in a combined pulling and pendulum motion. 
     
     
         35 . The system of  claim 26 , wherein the machine vision system is configured to determine a location of a piece of produce that is nearest to and reachable by the end-effector. 
     
     
         36 . The system of  claim 26 , wherein the machine vision system is configured to identify and localize pieces of produce at the beginning of each harvest cycle. 
     
     
         37 . The system of  claim 36 , where the machine vision system is configured to identify and localize pieces of produce only at the beginning of each harvest cycle. 
     
     
         38 . The system of  claim 26 , wherein the machine vision system is configured to identify clearly visible fruit using Circular Hough transformation. 
     
     
         39 . The system of  claim 38 , wherein the machine vision system is further configured to identify individual apple clusters using Circular Hough transformation. 
     
     
         40 . The system of  claim 26 , wherein the machine vision system is configured to identify partially visible fruit using block analysis. 
     
     
         41 . The system of  claim 26 , wherein the machine vision system comprises a CCD color camera and a time-of-fight based three-dimensional (3D) camera. 
     
     
         42 . The system of  claim 41 , wherein the machine vision system is configured to identify apples by acquiring color images with the CCD camera and to localize apples in three-dimensional space with the 3D camera. 
     
     
         43 . A method of autonomous robotic harvesting of produce, comprising
 determining with a machine vision system a location of a piece of produce to be harvested;   positioning with a manipulator an end-effector in three-dimensional space such that the end effector is guided to the determined location of the piece of produce to be harvested;   grasping the piece of produce with a plurality of tendon-driven, underactuated fingers of the end-effector, wherein the grasping comprises a power grasp, and wherein the grasping comprises independently actuating the plurality of fingers with a plurality of actuators; and   picking and dropping the piece of produce.   
     
     
         44 . The method of  claim 43 , wherein the positioning step comprises approaching the piece of produce along an azimuth angle.