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A master's thesis from Aalborg University
Book cover


Adaptive Backstepping Control of Asymmetric Electro-Hydraulic System

Translated title

Adaptiv Backstepping Kontrol af Asymmetrisk Elektro-Hydraulisk System

Author

Term

4. term

Publication year

2012

Submitted on

Pages

160

Abstract

Projektet udvikler og evaluerer styringsdesign baseret på backstepping til et asymmetrisk elektrohydraulisk system med stærkt ikke-lineær adfærd, store forstyrrelser og parametervariationer, herunder påvirkninger der ikke kan modvirkes direkte (unmatched). Først udvikles en ikke-lineær model af systemet og verificeres med eksperimenter. Derefter designes en robust, adaptiv backstepping-regulator med både ikke-lineær og lineær parameteradaptation. Der gives en matematisk garanti for stabilitet og for, at følgefejlen holdes inden for en på forhånd fastsat grænse. Der foreslås også en forenklet backstepping-regulator, der bygger på den mere omfattende løsning, men hvor den indre styresløjfe bruger en forenklet, lineariseret model af trykdynamikken. Det reducerer antallet af parametre og gør designet realiserbart i det eksperimentelle setup. Robustheden af denne regulator blev påvist i både simulationer og eksperimenter, og simulationerne viste god følgningspræstation selv ved store parametervariationer og forstyrrelser.

This project develops and evaluates controller designs based on the backstepping method for an asymmetric electro-hydraulic system with strong nonlinear behavior, large disturbances, and parameter variations, including disturbances that cannot be directly counteracted (unmatched). First, a nonlinear model of the system is built and verified with experiments. Next, a robust adaptive backstepping controller is designed with both nonlinear and linear parameter adaptation. A mathematical guarantee of stability is provided, ensuring that the tracking error stays within a preset bound. A simplified backstepping controller is also proposed: it is derived from the full design but uses a simplified, linearized model of the pressure dynamics in the inner control loop to reduce the number of parameters and make the design practical for the experimental setup. The robustness of this controller is demonstrated in both simulations and experiments, and the simulations show good tracking performance even under large parameter changes and disturbances.

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