As measured by task completion time in a 6 DOF docking task, the experiment has conclusively shown that the Fball is a more efficient isotonic position control device than the glove for this class of manipulation tasks, although this performance advantage was not unanimously supported by subjective ratings.
Theoretically, there are two major differences between the Fball
and the glove. The Fball allows the use of finger joints in addition
to the shoulder, elbow and wrist, while the glove uses the shoulder,
elbow and wrist only. The second difference is that the glove
utilises a clutch to resolve the limited range of rotation by
the wrist and the arm, by allowing the user to release the object
and reset the hand position (re-clutching). The re-clutching process
takes a certain amount of time. Figure 4.9 shows the mean completion
time with the Fball, the mean completion time with the glove,
and the re-clutching time with the glove, all from test 5. The
mean re-clutching time in test 5 was 1.056 second, accounting
for 10.7 % of the mean completion time with the glove. Statistical
results demonstrated that the use of finger joints for the Fball
operation must be beneficial, since the Fball outperforms the
glove even if the re-clutching times with the glove are subtracted
from the total completion times.