Control of Robot
Author
Manganas, Ioannis
Term
4. term
Education
Publication year
2018
Abstract
Denne afhandling omhandler styring af elektrohydrauliske aktuatorer, der fungerer som ledaktuatorer i en 2DOF manipulator. Det indledende mål er at udvikle en integrator-backstepping-regulator, der undgår den velkendte “eksplosion af termer” og samtidig bevarer Lyapunov-baserede resultater for begrænsethed og stabilitet. Et ikke-lineært modelapparat for manipulatoren og de symmetriske hydraulikcylindre udvikles og valideres mod laboratoriemålinger. Med udgangspunkt i et litteraturstudie af forenklede backstepping-metoder for elektrohydrauliske servosystemer tilpasses en kandidatdesign til anlægget; det viser sig dog vanskeligt at bevise stabilitet for det lukkede system. Afhandlingen foreslår derfor en alternativ reguleringsstrategi, hvor de første trin af en adaptiv backstepping-struktur kombineres med en sliding-mode forstyrrelsesobservatør for at estimere og kompensere usikkerheder og forstyrrelser uden at øge designkompleksiteten. For den foreslåede regulator opnås Lyapunov-baserede begrænsethedsresultater. Effektiviteten vurderes i simulering og sammenlignes med reference-regulatorer ved hjælp af udvalgte ydeevneindikatorer, og der udføres en følsomhedsanalyse over for centrale hydrauliske og mekaniske parametre. Resultaterne peger på effektiv sporingspræstation og øget robusthed over for parametervariationer sammenlignet med reference-løsningerne, samtidig med at den høje kompleksitet i fuld backstepping undgås.
This thesis addresses the control of electro-hydraulic actuators used as joint drives in a 2DOF robotic manipulator. The initial objective is to realize an integrator backstepping controller that mitigates the well-known explosion of terms while retaining Lyapunov-based guarantees of boundedness and stability. A nonlinear model of the manipulator and its symmetric hydraulic cylinders is developed and validated against laboratory measurements. Building on a survey of simplified backstepping methods for electro-hydraulic servo systems, a candidate design is adapted to the plant; however, formal stability proofs for the resulting closed-loop system prove difficult. The thesis therefore proposes an alternative control scheme in which the first steps of an adaptive backstepping structure are combined with a sliding-mode disturbance observer to estimate and compensate uncertainties and disturbances without increasing design complexity. For this controller, boundedness of the closed-loop signals is established within a Lyapunov framework. The effectiveness of the proposed algorithm is evaluated in simulation and benchmarked against reference controllers using selected performance metrics, and a sensitivity analysis is conducted with respect to key hydraulic and mechanical parameters. The results indicate effective tracking and improved robustness to parameter variations compared with the reference solutions, while avoiding the complexity typically associated with full backstepping implementations.
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