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YU Jinying
ZHAO Keding
CAO Jian
Department of Mechanical Engineering,
Harbin Institute of Technology,
Harbin 150001, China
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IMPROVED QUANTITATIVE
FEEDBACK THEORY TECHNIQUE AND APPLICATION TO THREE-AXIS
HYDRAULIC SIMULATOR
Abstract:
In order to meet tracking performance index of three-axis hydraulic simulator, based on classical quantitative feedback theory (QFT), an improved QFT technique is used to synthesize controller of low gain and bandwidth. By choosing a special nominal plant, the improved method assigns relative magnitude and phase tracking error between system uncertainty and nominal control plant. Relative tracking error induced by system uncertainty is transformed into sensitivity problem and relative tracking error induced by nominal plant forms into a region on Nichols chart. The two constraints further form into a combined bound which is fit for magnitude and phase loop shaping. Because of leaving out pre-filter of classical QFT controller structure, tracking performance is enhanced greatly. Furthermore, a cascaded two-loop control strategy is proposed to heighten control effect. The improved technique’s efficacy is validated by simulation and experiment results.
Key words:
Three-axis hydraulic simulator Quantitative feedback theory (QFT) Cascaded two-loop |