10



 1




 .01
 .01 I


 .001-. ... ... . ... ...
 .1 1 3.1 6.9 10 100
 ( (rad/sec)

 0-


 -90


 30 -180-

 .coI
 -1 -270


 -360- .... ... .. I ...
 .1 1 3.1 6.9 10 100
 ( (rad/sec)

Figure 9.15. Closed-loop magnitude and phase plots for joint 0 vision control system:
 K = 4.0 (D/A word)/pixel Kp = 2.27 pixels/(D/A word)
 ri= 0.02 sec 8= 0.18
 Td = 0.01 sec oh = 17 rad/sec


Static Performance

 Even though the requirements for the amplitude ratio and the phase lag were not met

for the vision systems, the responses of the controlled systems were still respectable. The

actual performance of each of the vision systems to position the end-effector within reach of a

targeted fruit proved sufficient for most cases. In fact, their steady-state performance proved

that still fruit could be approached with errors of 6 pixels or less (Figures 9.18 and 9.19). The

first test (Figure 9.18), an artificial fruit was positioned so that it was above the center of the