{
  "abstract": "Disturbances from multiple sources propagate through coupled motor, hydraulic, and mechanical channels in electro-hydrostatic actuators, while increasing observer bandwidth introduces a trade-off with sensitivity to high-frequency components. To address these challenges, this study proposes a cascaded control method that integrates parallel disturbance estimation with fractional-order error damping. A detailed model incorporating the instantaneous flow rate of a piston pump, leakage, fluid compressibility, and dynamic friction is developed, and a control-oriented model is derived through time-scale separation. A three-channel parallel observer is constructed according to the locations at which disturbances enter the state equations, enabling corresponding compensation within a position–pressure difference–rotational speed backstepping control cascade. A Caputo fractional derivative is introduced into the motor-level error feedback to shape the magnitude and phase characteristics within the target frequency band by adjusting the fractional order and damping gain. This term is implemented using a rational approximation over a finite frequency band. The approximation filter states are incorporated into a composite Lyapunov function. Under prescribed filter dissipation conditions, positive feedback gains, and uniformly bounded equivalent residuals, uniform ultimate boundedness of the augmented continuous-time closed-loop error dynamics is established, together with residual-dependent error bounds. Co-simulation results show that the position root-mean-square error during multilevel step tracking is 5.68 mm, representing reductions of 45.8%, 24.6%, and 12.6% relative to proportional–integral–derivative control, fractional-order linear active disturbance rejection control, and cascaded sliding-mode control with multiple-disturbance observation, respectively. In semi-physical experiments, the steady-state position error during the plateau phases remains largely within ±2 mm under loads of 5 kN and 10 kN. During motion-reversal tracking under variable loads, the position root-mean-square error is reduced by 26.8% and 14.8% relative to the first two baseline methods, respectively. These results demonstrate that, under the tested conditions, channel-specific disturbance compensation combined with fractional-order dynamic shaping improves actuator tracking performance and provides a basis for fractional-order controller design and finite-dimensional implementation analysis in coupled electrohydraulic systems.",
  "abstract_shown": true,
  "affiliations": [
    "School of Artificial Intelligence, Wuhan University of Technology, Wuhan 430070, China",
    "College of Electrical Engineering, Northwest Minzu University, Lanzhou 730124, China",
    "Hubei ChuangSiNuo Electrical Technology Corp., Enshi 445000, China"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Shuai Cao",
      "orcid": "0009-0002-5663-8858"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Weibo Li"
    },
    {
      "affs": [
        2
      ],
      "name": "Xiaoqing Deng"
    },
    {
      "affs": [
        2
      ],
      "name": "Yingting Deng"
    },
    {
      "affs": [
        2
      ],
      "name": "Qing Li"
    },
    {
      "affs": [
        2
      ],
      "name": "Junyi Zeng"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fay2h1cyvzb3b.bib",
  "cited_by": 0,
  "doi": "10.3390/fractalfract10100729",
  "fulltext_url": null,
  "id": "fay2h1cyvzb3b",
  "issns": [
    "2504-3110"
  ],
  "landing_url": "https://www.mdpi.com/2504-3110/10/10/729",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2210|Hydraulic and Pneumatic Systems"
    ]
  ],
  "openalex": "W7223067642",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-20",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/fay2h1cyvzb3b.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:32Z",
      "native_id": "10.3390/fractalfract10100729",
      "source": "crossref",
      "url": "https://www.mdpi.com/2504-3110/10/10/729"
    }
  ],
  "subjects": [
    {
      "field": "mathematics",
      "origin": "issn:2504-3110",
      "subfield": "analysis-pdes"
    }
  ],
  "title": "Hierarchical Fractional-Order Disturbance-Rejection Control of an Electro-Hydrostatic Actuator for Marine Steering Gear",
  "title_text": "Hierarchical Fractional-Order Disturbance-Rejection Control of an Electro-Hydrostatic Actuator for Marine Steering Gear",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:32Z",
  "url": "https://research.draconitic.com/paper/fay2h1cyvzb3b",
  "venue": "Fractal and Fractional",
  "versions": []
}