Phase-Based Repetitive Control for Rehabilitation Systems: A Case Study on Ankle Assistance

Öz

Active ankle foot orthoses (AAFOs) are widely used in gait rehabilitation to assist patients with impaired dorsiflexion and plantarflexion control. Due to the cyclic and quasi-periodic nature of human walking, repetitive disturbances and tracking errors frequently arise from actuator dynamics, transmission nonlinearities, and human device interaction forces. This article presents a phase based repetitive control (RC) framework specifically tailored for AAFO systems and integrated with a baseline impedance like controller to ensure safe and compliant assistance. By embedding an internal model of gait periodicity through phase synchronized learning, the proposed controller progressively reduces cycle to cycle tracking errors while remaining robust to cadence variations. A simulation case study demonstrates that the AAFO can learn a phase dependent assistive torque profile, resulting in improved tracking accuracy and smooth assistance under variable gait conditions. The results highlight the suitability of repetitive control as an interpretable and performance enhancing strategy for rehabilitation oriented biomechatronic devices.

Anahtar Kelimeler

• Repetitive
• control
• rehabilitation
• ankle

Rehabilitasyon Sistemleri için Faz Tabanlı Tekrarlayan Kontrol: Ayak Bileği Destek Sistemi Üzerine Bir Vaka Çalışması

Öz

Aktif ayak bileği-ayak ortezleri (AAFO'lar), ayak bileği dorsifleksiyon ve plantarfleksiyon kontrolünde bozukluk yaşayan hastalara yardımcı olmak için yürüyüş rehabilitasyonunda yaygın olarak kullanılmaktadır. İnsan yürüyüşünün döngüsel ve yarı periyodik doğası nedeniyle, aktüatör dinamikleri, iletim doğrusal olmayanlıkları ve insan-cihaz etkileşim kuvvetlerinden kaynaklanan tekrarlayan bozulmalar ve izleme hataları sıklıkla ortaya çıkar. Bu makale, AAFO sistemleri için özel olarak tasarlanmış ve güvenli ve uyumlu destek sağlamak için temel empedans benzeri bir kontrolörle entegre edilmiş faz tabanlı tekrarlayan kontrol (RC) çerçevesini sunmaktadır. Faz senkronize öğrenme yoluyla yürüyüş periyodikliğinin içsel bir modelini yerleştirerek, önerilen kontrolör, kadans varyasyonlarına karşı sağlam kalırken döngüden döngüye izleme hatalarını kademeli olarak azaltır. Bir simülasyon vaka çalışması, AAFO'nun faza bağlı bir yardımcı tork profili öğrenebileceğini ve bunun da değişken yürüyüş koşulları altında izleme doğruluğunu ve düzgün desteği iyileştirdiğini göstermektedir. Sonuçlar, tekrarlayan kontrolün rehabilitasyon odaklı biyomekatronik cihazlar için yorumlanabilir ve performansı artırıcı bir strateji olarak uygunluğunu vurgulamaktadır.

Anahtar Kelimeler

• Tekrarlayan
• kontrol
• rehabilitasyon
• ayak bileği

Kaynakça

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