Research Article

Proportional-Derivative Observer-Based Backstepping Control for an Underwater Manipulator

Figure 10

Time trajectories of the task space ( ) errors for the circular trajectory in an uncertain and disturbed condition.
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(a) Position tracking errors in PID
397092.fig.0010b
(b) Position observer errors in PID
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(c) Position tracking errors in MRC
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(d) Position observer errors in MRC