Robust output feedback assistive control of a compliantly actuated knee exoskeleton

Kardan, Iman; Akbarzadeh, Alireza

doi:10.1016/j.robot.2017.09.006

Cited by 25 publications

(7 citation statements)

References 33 publications

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“…It is because a larger closed loop bandwidth can be achieved by C2 due to considering all characteristic of system dynamics, which results in larger high-level controller gains and adaptive rates. Then, better parameter estimation and force control performance 16 Applied Bionics and Biomechanics can be achieved by FARC+C2. In Set3, a 2:72kg weight is mounted at the shank to study the performance of the proposed ARCFC to parameter variation.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…Also, the proposed low-level motion tracking algorithm cannot guarantee the fast response and accurate tracking of human motion in the presence of strongly coupled nonlinearities and various model uncertainties. Other control methods have considered the model uncertainties in the controller design, such as the adaptive impedance control [12], neural network control [13], sliding mode controller [14,15], and robust output feedback-assistive control [16]. However, these methods are mainly focused on the controller design of motor-driven exoskeletons which cannot be easily extended to the control of hydraulic exoskeletons.…”

Section: Introductionmentioning

confidence: 99%

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Generalized Multiphase Dynamic Modeling and Precision Interaction Force Control of a Walking Lower Limb Hsydraulic Exoskeleton

Chen

Dong

et al. 2022

Applied Bionics and Biomechanics

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Wearable lower limb hydraulic exoskeletons can be used to augment the human performance in heavy load transportation. Nonlinear and walking phase-dependent dynamics make the lower limb hydraulic exoskeleton become difficult to be modeled. This paper presents a generalized multiphase dynamic modeling method in which the dynamic model of each walking phase can all be solved based on a general higher dimensional dynamic model and different holonomic constraints. Compared to traditional lower limb exoskeleton modeling methods where the modeling of each walking phase is done independently, the proposed method is simple and applicable to arbitrary walking phases, especially for double leg support phase (closed-chain dynamics). Based on the established dynamic models, MIMO adaptive robust cascade force controllers (ARCFC) are designed both for double leg support phase and single leg support phase to effectively address high-order nonlinearities and various modeling uncertainties in hydraulic exoskeletons. An additional torque allocation method is proposed to deal with the overactuated characteristic in double leg support. Comparative simulations are conducted to verify the excellent human-machine interaction force control performance of the proposed scheme.

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Section: Simulation Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Generalized Multiphase Dynamic Modeling and Precision Interaction Force Control of a Walking Lower Limb Hsydraulic Exoskeleton

Chen

Dong

et al. 2022

Applied Bionics and Biomechanics

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“…Many examples of electric motors producing linear motion are actually rotary electric motors paired with Ball screws. [27,32,35], and [36] make use of Ball Screws to convert the rotational motion of a rotary electric motor into linear motion, becoming a type of electric linear actuator. In [27], the motor is connected via a pulley and timing belt to the ball screw, that then provides the translational push-pull motion to the supported ankle.…”

Section: Functionmentioning

confidence: 99%

“…In [27], the motor is connected via a pulley and timing belt to the ball screw, that then provides the translational push-pull motion to the supported ankle. [35] uses a similar ball screw method but integrates an additional compliant spring element, the ball screw forms an inner shaft that moves a spring element that connects to the outer shaft. This compliant element is seen in series elastic actuator designs and can be used to allow for minor movements in the leg without necessitating motor movement, as well as resisting backlash.…”

Section: Functionmentioning

confidence: 99%

A Systematic Review of Low-Cost Actuator Implementations for Lower-Limb Exoskeletons: a Technical and Financial Perspective

Slucock

2022

J Intell Robot Syst

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A common issue with many commercial rehabilitative exoskeletons and orthoses are that they can be prohibitively expensive for an average individual to afford without additional financial support. Due to this a user may have limited to the usage of such devices within set rehabilitation sessions as opposed to a continual usage. The purpose of this review is therefore to find which actuator implementations would be most suitable for a simplistic, low-cost powered orthoses capable of assisting those with pathologic gait disorders by collating literature from Web of Science, Scopus, and Grey Literature. In this systematic review paper 127 papers were selected from these databases via the PRISMA guidelines, with the financial costs of 25 actuators discovered with 11 distinct actuator groups identified. The review paper will consider a variety of actuator implementations used in existing lower-limb exoskeletons that are specifically designed for the purpose of rehabilitating or aiding those with conditions inhibiting natural movement abilities, such as electric motors, hydraulics, pneumatics, cable-driven actuators, and compliant actuators. Key attributes such as technical simplicity, financial cost, power efficiency, size limitations, accuracy, and reliability are compared for all actuator groups. Statistical findings show that rotary electric motors (which are the most common actuator type within collated literature) and compliant actuators (such as elastic and springs) would be the most suitable actuators for a low-cost implementation. From these results, a possible actuator design will be proposed making use of both rotary electric motors and compliant actuators.

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“…[30] Integral admittance shaping... Robotics and Autonomous Systems. [31] Output feedback assistive control of single-dof sea powered exoskeletons. [32] Robust output feedback assistive control of a compliantly ... [33] Kinematic analysis and optimization of a planar parallel ... [34] Clinical gait analysis: theory and practice.…”

mentioning

confidence: 99%

Design and implementation of a fuzzy output feedback assistive controller for a series-elastic-actuator-driven knee exoskeleton

Ashrafi

Nazari²,

Sepehry³

et al. 2022

Modares Mechanical Engineering

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The series elastic actuators make more comfort in the use of assistive exoskeletons. In this paper, an assistive controller is designed for a series-elastic-actuator-driven knee exoskeleton to restore normative mobility of individuals with weak muscles. The main target of the proposed controller is to modify the dynamics performance of the coupled humanexoskeleton system. In other words, the proposed controller modifies the relationship between the net muscle torque exerted by the human and the resulting angular motion. There are fewer sensors in the proposed intent-independent method relative to other methods. Moreover, there are less controller coefficients to regulate where these coefficients are extracted from a type zero Takagi-Sugeno-Kang fuzzy system. The performance of the controller is evaluated by simulations and experiments. The amplitude of the EMG signals decreased in a healthy person worn the SUT-KneeExo. Moreover, the proposed algorithm has a better performance in comparison with integral admittance shaping mothed and output feedback assistive controller. In other words, the amplitude of the integral admittance is more and the phase lag is less than other methods.

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Robust output feedback assistive control of a compliantly actuated knee exoskeleton

Cited by 25 publications

References 33 publications

Generalized Multiphase Dynamic Modeling and Precision Interaction Force Control of a Walking Lower Limb Hsydraulic Exoskeleton

Generalized Multiphase Dynamic Modeling and Precision Interaction Force Control of a Walking Lower Limb Hsydraulic Exoskeleton

A Systematic Review of Low-Cost Actuator Implementations for Lower-Limb Exoskeletons: a Technical and Financial Perspective

Design and implementation of a fuzzy output feedback assistive controller for a series-elastic-actuator-driven knee exoskeleton

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