Sequential time-dependent reliability analysis for the lower extremity exoskeleton under uncertainty

Yu, Shui; Wang, Zhonglai; Zhang, Kewang

doi:10.1016/j.ress.2017.10.006

Cited by 69 publications

(27 citation statements)

References 26 publications

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“…Uncertainties in practical systems can be divided into two parts, namely internal interference and external uncertainty [41][42][43]. The former mainly includes the case where the parameters such as mass and rotational inertia of the system are unknown, while the latter mainly refers to some unmodeled dynamics such as external disturbance and friction.…”

Section: Adaptive Fuzzy Approximationmentioning

confidence: 99%

Novel Design and Adaptive Fuzzy Control of a Lower-Limb Elderly Rehabilitation

Zhang

Chen

et al. 2020

Electronics

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Design and control of a lower-limb exoskeleton rehabilitation of the elderly are the main challenge for health care in the past decades. In order to satisfy the requirements of the elderly or disabled users, this paper presents a novel design and adaptive fuzzy control of lower-limb empowered rehabilitation, namely MOVING UP. Different from other rehabilitation devices, this article considers active rehabilitation training devices. Firstly, a novel product design method based on user experience is proposed for the lower-limb elderly exoskeleton rehabilitation. At the same time, in order to achieve a stable operation control for the assistant rehabilitation system, an adaptive fuzzy control scheme is discussed. Finally, the feasibility of the design and control method is validated with a detailed simulation study and the human-interaction test. With the booming demand in the global market for the assistive lower-limb exoskeleton, the methodology developed in this paper will bring more research and manufacturing interests. Electronics 2020, 9, 343 2 of 17 the effectiveness of rehabilitation training. A wearable upper limb therapy robot based on Pneumatic Muscle Actuator (PMA) was introduced in Reference [13]. This device has five degrees of freedom, works similarly to human muscle functions, has high compliance and safety. Besides, Reference [14] developed a cable drive for the exoskeleton, which has seven degrees of freedom and can be used in medical, remote control, test research, and other fields.In general, the structure of the exoskeleton rehabilitation device is simple, but it is challenging to carry out rehabilitation training for the local body parts, and the rehabilitation effect is not ideal [15,16]. The research of the end-effector rehabilitation device is mainly used in limb rehabilitation, remote control, and other fields, and its research direction focuses on improving freedom, ensuring safety and reducing complexity, and so forth. Existing exoskeleton rehabilitation devices are complicated and expensive, and they are mostly used in experiments and difficult to achieve marketization. Both types of rehabilitation devices have their own advantages and disadvantages. It is necessary to select a suitable rehabilitation device type in specific applications and match different training modes to achieve a better training effect [17].The early version in Reference [18] developed by the Federal Institute of Technology in Zurich, was passive gait training. Continuous passive movement (CPM) machines and simple rehabilitation treadmills, which are widely used in clinical practice, generally only provide passive training modes. An ankle rehabilitation robot based on steady-state visual evoked potentials was discussed in Reference [19], which combined SSVEP signals with a virtual reality environment and was able to determine the subject's intention to perform passive training. In addition, for rule-based control structures, a human-machine interface was presented in Reference [20]. The robot manipulator (RM) can pe...

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Section: Adaptive Fuzzy Approximationmentioning

confidence: 99%

Novel Design and Adaptive Fuzzy Control of a Lower-Limb Elderly Rehabilitation

Zhang

Chen

et al. 2020

Electronics

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“…Although many researches have been published in this field, challenges still exist for simulating the fluidstructure coupled effect of blades accurately in practical engineering, especially in the situation that there are high design dimensions and non-linearity MDO problems. [30][31][32][33][34][35][36] To solve the above problem, a fluid-structure multidisciplinary analysis approach is proposed here. The total pressure ratio and the adiabatic efficiency of blades are analyzed here by the given method.…”

Section: Introductionmentioning

confidence: 99%

Structural reliability analysis and uncertainties‐based collaborative design and optimization of turbine blades using surrogate model

Meng

Yang

Zhang³

et al. 2018

Fatigue Fract Eng Mat Struct

137

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In power and energy systems, both the aerodynamic performance and the structure reliability of turbine equipment are affected by utilized blades. In general, the design process of blade is high dimensional and nonlinear. Different coupled disciplines are also involved during this process. Moreover, unavoidable uncertainties are transported and accumulated between these coupled disciplines, which may cause turbine equipment to be unsafe. In this study, a saddlepoint approximation reliability analysis method is introduced and combined with collaborative optimization method to address the above challenge. During the above reliability analysis and design optimization process, surrogate models are utilized to alleviate the computational burden for uncertainties‐based multidisciplinary design and optimization problems. Smooth response surfaces of the performance of turbine blades are constructed instead of expensively time‐consuming simulations. A turbine blade design problem is solved here to validate the effectiveness and show the utilization of the given approach.

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“…Since the mechanical systems become more and more complex, multi-failure modes occurring and time-consuming design of experiments (DOE), instantaneous reliability estimation techniques by data-driven technology combining with physics of failure modeling methods have been developed and widely used in aerospace, transportation, oil and gas exploration, and petrochemical industries. [8][9][10][11][12] In these studies, how to choose key points to improve the accuracy and efficiency of physics of failure modeling, and the performance of different surrogate modeling methods were recently studied and demonstrated. Due to the more complex uncertainty, time-dependent reliability estimation is more complex than the traditional ones.…”

Section: Introductionmentioning

confidence: 99%

A time-dependent reliability estimation method based on surrogate modeling and data clustering

Peng

Huang

et al. 2019

Advances in Mechanical Engineering

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Due to the complex uncertainty of working loads and design parameters, time-dependent reliability estimation is timeconsuming. Various works aim to improve the accuracy and efficiency of time-dependent reliability estimation methods with a known time-dependent response of the mechanical system. Time-dependent reliability calculation with complex uncertainty and unknown limit state function are more complex. In this article, surrogate modeling and data clustering technology are utilized to estimate the time-dependent reliability of mechanical structure. First, the physics of failure with respect to time for a mechanical structure is analyzed, and BP neural network is introduced to build the surrogate model of time-dependent response for mechanical structure. Second, data clustering technique is used to find the most probable failure domains. Furthermore, the Genetic Algorithm is utilized to search the extreme values of the response at the most probable failure points during the given time interval. Then, the surrogate model for the extreme values at the most probable failure points is approximately established using BP neural network and Monte Carlo simulation is used for time-dependent reliability estimation. Finally, two examples are presented to verify the accuracy and efficiency of the proposed method.

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Sequential time-dependent reliability analysis for the lower extremity exoskeleton under uncertainty

Cited by 69 publications

References 26 publications

Novel Design and Adaptive Fuzzy Control of a Lower-Limb Elderly Rehabilitation

Novel Design and Adaptive Fuzzy Control of a Lower-Limb Elderly Rehabilitation

Structural reliability analysis and uncertainties‐based collaborative design and optimization of turbine blades using surrogate model

A time-dependent reliability estimation method based on surrogate modeling and data clustering

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