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Observer Based Robust-Adaptive Fractional-Order Control for Cable Parallel Robots in the Presence of Perturbations and Model Uncertainties Characterized by Unknown Nonlinear Functional Upper Bounds
  • Mansour Peimani ,
  • Farzad Jafarlou,
  • Nasser Lotfivand
Mansour Peimani
Islamic Azad University Tabriz Branch

Corresponding Author:[email protected]

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Farzad Jafarlou
Islamic Azad University Tabriz Branch
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Nasser Lotfivand
Islamic Azad University Tabriz Branch
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Abstract

This article investigates the challenges of stabilizing Cable Suspended Parallel Robots (CSPRs) when dealing with uncertainties in models and external disturbances. It presents a novel Robust Adaptive Fractional-Order Sliding Mode Controller (RAFOSMC) designed specifically to handle uncertain nonlinear functional upper bounds that define disturbances and uncertainties. The approach employs stable adaptive laws to determine the unknown coefficients within the perturbation functional upper bounds. Analysis demonstrates that the Fractional-Order Sliding Mode Controller (FOSMC) surpasses traditional Integer-Order Sliding Mode Controllers (IOSMC). FOSMC exhibits advantages such as decreased chattering, swifter convergence toward the intended trajectory during initial movement, and eventual finite-time convergence to the fractional sliding surface. The study also proposes an innovative approximation for the sign function to further minimize chattering. Additionally, for situations where cable states are unavailable, the study introduces a nonlinear observer capable of estimating both cable position and model perturbations. Simulation results and comparisons with recent research support the efficacy of the proposed approaches.