The use of root-locus-based robust design techniques in the design of a digital controller for a high-performance variable-amplitude fatigue test is described. Evaluation of the resulting controller on a prototype laboratory materials testing system, designed to simulate the mechanical stress loads experienced by certain aircraft components, shows that it meets design performance goals of 0.25% specimen load accuracy while providing robustness to specimen compliance over a 10 to 1 range. This performance significantly exceeds that obtained with traditional hand-tuned controllers. >

In this paper the model development, problem specification, constraint formulation, and optimal feedback controller design for a variable-displacement hydraulic pump system are shown using the Quantitative Feedback Theory (QFT) technique. The use of variable-displacement pumps in hydraulic system applications has become widespread due to their efficiency 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 in operating point-dependent parameters. After presentation of a realistic non-linear differential equation model, the linearized model is developed and the effect of parametric uncertainty is reviewed. From this point, closed-loop performance specifications are formulated and the QFT design technique is carried out. An initial feasible controller is 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 terms of the detailed hydraulic system model development, as well as in terms of the detailed exposition of the QFT controller design and optimal loop shaping processes. © 1998 John Wiley & Sons, Ltd.

Robust control for high-performance materials testing

Quantitative feedback design for a variable-displacement hydraulic vane pump

From the Publisher:
This well-respected, market-leading text discusses the use of digital computers in the real-time control of dynamic systems The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude Both classical and modern control methods are described and applied to illustrative examples The strengths and limitations of each method are explored to help the reader develop solid designs with the least effort Two new chapters have been added to the third edition offering a review of feedback control systems and an overview of digital control systems Updated to be fully compatible with MATLAB versions 4 and 5, the text thoroughly integrates MATLAB statements and problems to offer readers a complete design picture The new edition contains up-to-date material on state-space design and twice as many end-of-chapter problems to give students more opportunities to practice the material

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Robust control for high-performance materials testing

Citations

Quantitative feedback design for a variable-displacement hydraulic vane pump

References

Digital control of dynamic systems

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