Fractional multi-loop active disturbance rejection control for a lower knee exoskeleton system

Rehabilitation Exoskeleton is becoming more and important in physiotherapists’ routine work. To improve the treatment performance, such as reducing recovery period and/or monitoring reacting to unpredictable situations, rehabilitation manipulators need help patients various physical trainings. A special case of active disturbance rejection control (ADRC) applied govern a proper realisation basic limb The experimental study performed on model flexible joint manipulator, whose behaviour resembles real exoskeleton device (a one-degree-of-freedom, rigid-link, flexible-joint manipulator). fractional (FADRC) an unconventional model-independent approach, acknowledged effective controller existence total plant uncertainties, these uncertainties are inclusive disturbances unknown dynamics plant. In this work, three FADRC schemes used, first one using state observer (FSO), or FADRC1, second proportional-derivative (FPD), FADRC2, third Multi-loop PD-loop observer-loop (Feedforward Feedback), FADRC3. simulated system subjected noise FADRC3 shows effectiveness compensate all effects satisfies desired position when compared with FADRC1 FADRC2. design simulation were carried out MATLAB/Simulink.