Comparison of Controllers for a Separate Meter-In and Separate Meter-out System
Authors
Fleischer, Oliver Gregory Inuk Slaughter ; Zubarev, Sergej
Term
4. term
Education
Publication year
2020
Submitted on
2020-05-29
Pages
110
Abstract
This thesis analyzes and compares control methods for a separate meter-in/separate meter-out (SMISMO) hydraulic system with two proportional valves and a single-degree-of-freedom inertial load. The study is simulation-based without a test bench: a nonlinear model is developed, checked against steady-state calculations, and then linearized for system analysis and controller design. The linear model is used to examine dynamics and input–output coupling to guide the choice of linearization point and the conservativeness of tuning. Under a pressure/velocity control strategy that tracks rod-side pressure and piston velocity, multi-input multi-output controllers based on full-state feedback and the linear-quadratic family are designed. Controllers are first tested on the linear model; three candidates are then evaluated on the nonlinear model with measurement noise and an external force, for horizontal and vertical cylinder orientations. The results indicate that LQI performs best in the horizontal case, whereas LQG-I performs best in the vertical case. The work provides a modeling and comparison framework to support controller selection and tuning for SMISMO actuators, with the limitation that findings are based on simulations and lack experimental validation.
Dette speciale undersøger og sammenligner reguleringsmetoder for et separate meter-in/separate meter-out (SMISMO) hydraulisk system med to proportionalventiler og en inert belastning med én frihedsgrad. Arbejdet er en simuleringsundersøgelse uden testbænk; der udvikles en ikke-lineær model, som valideres med stationære beregninger og herefter lineariseres til brug for systemanalyse og regulatordesign. Den lineære model anvendes til at belyse dynamik og kobling mellem ind- og udgange for at informere valg af linearisationspunkt og graden af konservativ tuning. Med en strategi for samtidig regulering af stempelstangsside-tryk og stempelhastighed sammenlignes MIMO-regulatorer baseret på fuldtilstandsfeedback og lineær-kvadratiske metoder. Regulatorerne afprøves først i den lineære model og tre kandidater vurderes derefter i den ikke-lineære model under målestøj og en ekstern kraft, for både vandret og lodret cylinder. Resultaterne viser, at LQI klarer sig bedst i vandret position, mens LQG-I er bedst i lodret position. Arbejdet bidrager med en modellerings- og sammenligningsramme, der kan understøtte valg og tuning af controllere til SMISMO-aktuatorer, men er begrænset til simulering uden eksperimentel verifikation.
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