Experimental results for end-point positioning of multi-link flexible manipulators are considered. This control strategy has been implemented on an experimental test-bed developed at the Control/Robotics Research Laboratory at Polytechnic University. The advocated approach is based on a two-stage control design. The first stage is an inner-loop nonlinear-based controller corresponding to the rigid body motion of the manipulator. The second stage is an outer control loop based on linear output LQR design. The outer-loop control design results in a nonconvex nonlinear optimization problem. A software package has been developed to solve this problem. The outer-loop controller enhances vibration damping and robustness of the closed-loop dynamics to parameter variations. The measurement utilized for vibration suppression is through an accelerometer attached at the end point of the manipulator.