• Title/Summary/Keyword: active force control

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The control of an upper extremity exoskeleton for stroke rehabilitation: An active force control scheme approach

  • Majeed, Anwar P.P. Abdul;Taha, Zahari;Abdullah, Muhammad Amirul;Azmi, Kamil Zakwan Mohd;Zakaria, Muhammad Aizzat
    • Advances in robotics research
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    • v.2 no.3
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    • pp.237-245
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    • 2018
  • This study evaluates the efficacy of a class robust control scheme namely active force control in performing a joint based trajectory tracking of an upper limb exoskeleton in rehabilitating the elbow joint. The plant of the exoskeleton system is obtained via system identification method whilst the PD gains were tuned heuristically. The estimated inertial parameter that enables the AFC disturbance rejection effect is attained by means of a non-nature based metaheuristic optimisation technique known as simulated Kalman filter (SKF). It was demonstrated from the present investigation that the proposed PDAFC scheme outperformed the classical PD algorithm in tracking the prescribed trajectory both in the presence and without the presence of disturbance attributed by the mannequin limb weights (1 kg and 1.5 kg) that mimics the weight of actual human limb weight. Therefore, it is apparent from the results obtained from the present study that the proposed control scheme, i.e., PDAFC is suitable for the application of exoskeleton for stroke rehabilitation.

Active Force Control of Electro-Hydraulic Hybrid Load Simulator using Quantitative Feedback Theory (QFT를 이용한 전기유압 하이브리드 부하 시뮬레이터의 능동 힘제어)

  • Yoon, Joo-Hyeon;Ahn, Kyoung-Kwan;Truong, Dinh Quang;Jo, Woo-Geun
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.2
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    • pp.45-53
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    • 2009
  • Today, reduction of $CO_2$ exhaustion gas for global-warming prevention becomes important issues in all industrial fields. Hydraulic systems have been widely used in industrial applications due to high power density and so on. However hydraulic pump is always being operated by engine or electric motor in the conventional hydraulic system. Therefore most of the conventional hydraulic system is not efficient system. Recently, an electro-hydraulic hybrid system, which combines electric and hydraulic technology in a compact unit, can be adapted to a wide variety of force, speed and torque requirements. In the electro-hydraulic hybrid system, hydraulic pump is operated by electric motor only when hydraulic power is needed. Therefore the electro-hydraulic system can reduce the energy consumption drastically when compared to the conventional hydraulic systems. This paper presents a new kind of hydraulic load simulator which is composed of electro-hydraulic hybrid system. Disturbances in the real working condition make the control performance decrease or go bad. QFT controller is designed to eliminate or reduce the disturbance and improve the control performance of the electro-hydraulic load simulator. Experimental results show that the proposed controller is verified to apply for electro-hydraulic hybrid system with varied external disturbances.