fruit motion was large enough that the fruit would be lost by the vision system, the supervising

program would cause the robot to return to the search mode in search of another fruit.


 Overall Controller Performance

 Although acceptable performance was not demonstrated for all of the controllers when

 operated separately, their performance within the intelligence base was most important for

 this application. As previously mentioned, the ability of the controllers to move the end-

 effector to a previously determined position and orientation in its workspace was not of

 importance in this case. The capability of the controllers to repeat a motion was not important

 either. Rather, the usefulness of these controllers in the fruit-picking operation as governed by

 the intelligence base was of great significance. This capacity could be demonstrated only by

 examination of the pick cycle and the response of the motion controllers to the commands from

 the intelligence base. The velocity controllers for joints 0 and 1 were used only during the fruit

 search routine. Thus, data from a typical search routine are presented and discussed. Data

 plots from a typical pick cycle are presented for explaining the effectiveness of the position and

 vision controllers for joints 0 and 1 and the position and velocity controllers for joint 2. Also, the

 ability of the intelligence base to enhance the operation of the vision controllers for tracking

 the large and fast fruit motions is presented. The output from the velocity controller for joint 2

 was used for detection of collisions during the extension of the joint. The results of this

 technique are exhibited here.

 Performance in the Search Routine

 In the initial stages of the pick cycle, if a fruit was not detected in the image of the

vision system, the robot was instructed to begin a search routine. In this search routine, the

intelligence base called for velocity control on joints 0 and 1 for scanning the robot's workspace

and position control on joint 2 to hold the slider stationary. The direction of motion for both

revolute joints was changed when the joint reached a specified position. Data from a typical

search routine is presented in Figures 9.20 9.23. For this presentation, the robot began with