Novel concept in control of robot manipulators

The method uses Horowitz quantitative feedback theory (QFT) to design the feedback loop to stabilize the plant, to reduce the loop sensitivity, and to reject disturbances. A prefilter is used to shape the nominal transmission from reference to output Astrom. In the paper a QFT loop is used as the inner loop which should ensure a robust control, however to establish robustness the control action may be too lively. Differential adaptive control is then applied to provide fine tuning on control and dealing with plant uncertainties