QUANTITATIVE FEEDBACK DESIGN FOR A VARIABLE-DISPLACEMENT HYDRAULIC VANE PUMP

In this paper the model development, problem specification, constraint formulation, and optimal feedback controller design for a variable-di splacement hydraulic pump system are shown using the Quantitative Feed back Theory (QFT) technique. The use of variable-displacement pumps in hydraulic system applications has become widespread due to their effi ciency advantages; however, this efficiency gain is often accompanied by a degradation of system stability. Here we develop a QFT controller for a variable-displacement pump based upon a linear, parametrically uncertain model in which some of this uncertainty reflects variation i n operating point-dependent parameters. After presentation of a realis tic non-linear differential equation model, the linearized model is de veloped and the effect of parametric uncertainty is reviewed. From thi s point, closed-loop performance specifications are formulated and the QFT design technique is carried out. An initial feasible controller i s designed, and this design is optimized via a non-linear programming technique. In conclusion, a non-linear closed-loop system response is simulated, This paper is intended to have tutorial value, both in term s of the detailed hydraulic system model development, as well as in te rms of the detailed exposition of the QFT controller design and optima l loop shaping processes. (C) 1998 John Wiley & Sons, Ltd.