were mounted sprockets which were driven by a 25 pitch chain and a larger set of sprockets

providing a 3:1 drive ratio. The rear drive shaft, holding the larger set of sprockets, was

turned by a 5 cm long lever arm which converted the linear motion of the actuating cylinder to

rotary motion of the drive sprockets (Figure 4.10). A square aluminum linkage was connected

between the actuating cylinder and the lever arm. On the rear end of the sliding tube, the end

cap was bolted to the tube and used for mounting the actuator for the rotating lip picking

mechanism. On the forward end of the tube, an end cap was welded for mounting the end-

effector. Kinematic coordinate frame 3 was assigned to the end-effector (see Figure 4.1).

Fruit Sensor Package

 The sensor package for locating the fruit in the canopy of the tree was mounted inside of

the tube of the picking mechanism (Figure 4.11). The sensor package included a color CCD

camera, an ultrasonic ranging transducer, and four small light sources and provided the real-

time three-dimensional position sensing between the end of the arm and a fruit in the

manipulator's workspace.

 CCD camera. A Sony DXC-101 color CCD video camera with an 8 mm fixed focal length

and automatic aperture control lens was employed for detecting the fruit in the canopy of the

tree. The camera was mounted in the picking mechanism so that the optical axis of its lens was

approximately 25 mm below and parallel to the Z axis of the tube. The sensing element of the

camera was an 8.8 mm x 6.6 mm Charge Coupled Device (CCD) array. The CCD array was


 Picking
 Mechanism


Figure 4.10. Picking mechanism actuation assembly.