  This work presents the design and the corresponding stability analysis of a
model based, joint position tracking error constrained, adaptive output
feedback controller for robot manipulators. Specifically, provided that the
initial joint position tracking error starts within a predefined region, the
proposed controller algorithm ensures that the joint tracking error remains
inside this region and asymptotically approaches to zero, despite the lack of
joint velocity measurements and uncertainties associated with the system
dynamics. The need for the joint velocity measurements are removed via the use
of a surrogate filter formulation in conjunction with the use of desired model
compensation. The stability and the convergence of the closed loop system are
proved via a barrier Lyapunov function based argument. A simulation performed
on a two-link robotic manipulator is provided in order to illustrate the
feasibility and effectiveness of the proposed method.
