A reduced order observer for underwater manipulators using potentiometers for position measurements

In this paper an improved manipulator joint velocity observer is presented which is reduced in its order. The observer provides a smooth velocity estimate to be used by a trajectory tracking controller. The observer, controller and manipulator form a system where the observer error as well as the position and velocity tracking errors tend to zero asymptotically. The proposed observer is compared to numerical differentiation plus filtering as a means to provide a velocity signal which is used in control. When considering joint position signals corrupted with measurement noise, it is found that the proposed observer is superior in its performance compared to numerical differentiation plus filtering