industrial robots provided greater accuracy and more degrees of freedom than would be required

of a fruit harvester. Thus, a task-specific robot could be designed for the purpose of fruit

picking. A closed-loop system would be needed that could tie the sensing functions with the

arm motion controllers.

 Some of the earliest work in the development of the technology was conducted by

Parrish and Goksel (1977). These men studied the feasibility of analyzing the work space of

the robot by use of machine vision. In their study, a black-and-white video camera was used to

detect the fruit, which were represented by blobs in the two-dimensional picture array. By

analyzing their perimeters, the larger blobs which contained overlapping fruit were

successfully divided into separate fruit. The location of the fruit centroids were determined in

the two-dimensional picture array. Trajectories were calculated from the camera lens center to

the positions of the detected fruit centroids. The mechanical arm was driven to follow these

trajectories toward the fruit. When contact with a fruit was detected by a touch sensor, the

motion of the robot was halted. As fruit removal was not in the scope of this work, a successful

picking attempt was recorded when contact with the fruit was detected. In this work, a scene

was analyzed and one trajectory was calculated for each fruit in the scene. The arm was driven

until all of the trajectories were exhausted. Then, a new scene was analyzed, and the operation

was repeated. Although this system was quite elementary, the concepts and the feasibility of

robotically harvesting tree fruit were inspired. These concepts have been used as a motivation

for many of the later attempts.

 Grand d'Esnon (1984 and 1985) developed an apple picker which used similar ideas for

the detection of fruit. This manipulator was a cylindrical coordinate robot (PRP, prismatic in

the first joint, revolute in the second, and prismatic in the third). Using the vision system to

determine the fruit's position in two coordinates, the robot was pointed towards the fruit by

raising the arm along a vertical prismatic joint and then pivoting around a vertical axis. This

motion relied on the concept that the fruit did not move between the time that the image was

acquired and the picking tool reached the fruit. In a later attempt, Grand d'Esnon et al. (1987)