Biomechanical modeling and load-carrying simulation of lower limb exoskeleton

Zhu, Yanhe; Zhang, Guoan; Zhang, Chao; Liu, Gangfeng; Zhao, Jie

doi:10.3233/bme-151364

Cited by 23 publications

(16 citation statements)

References 14 publications

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“…6. The curve in the figure references the torque needed for level-walking; although the novel link decreased the initial torque, it was still able to guarantee the level-walking torque requirement [10]. In addition, the peak of the torque moved backwards significantly; this solved the question of whether the torque demand increased along with the joint angle augment.…”

Section: Kinematics Modelingmentioning

confidence: 84%

Biomechanical design of escalading lower limb exoskeleton with novel linkage joints

Zhang¹,

Liu²,

Ma³

et al. 2017

THC

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Abstract. In this paper, an obstacle-surmounting-enabled lower limb exoskeleton with novel linkage joints that perfectly mimicked human motions was proposed. Currently, most lower exoskeletons that use linear actuators have a direct connection between the wearer and the controlled part. Compared to the existing joints, the novel linkage joint not only fitted better into compact chasis, but also provided greater torque when the joint was at a large bend angle. As a result, it extended the angle range of joint peak torque output. With any given power, torque was prioritized over rotational speed, because instead of rotational speed, sufficiency of torque is the premise for most joint actions. With insufficient torque, the exoskeleton will be a burden instead of enhancement to its wearer. With optimized distribution of torque among the joints, the novel linkage method may contribute to easier exoskeleton movements.

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Section: Kinematics Modelingmentioning

confidence: 84%

Biomechanical design of escalading lower limb exoskeleton with novel linkage joints

Zhang¹,

Liu²,

Ma³

et al. 2017

THC

Self Cite

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“…After BLEEX, SAC is seldom being used in other exoskeletons for its strick requirements of the model. MBC, such as direct force control 7,8 and impedance control, 9,10 is relatively easy to implement. HEXAR-CR50 developed by Hanyang University uses direct force control to calculate the desired joint torques in the stance phase and then applied a proportional–integral–derivative (PID) controller at each joint.…”

Section: Introductionmentioning

confidence: 99%

Fuzzy cerebellar model articulation controller-based adaptive tracking control for load-carrying exoskeleton

Lang

et al. 2020

Measurement and Control

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Load-carrying exoskeletons need to cope with load variations, outside disturbances, and other uncertainties. This paper proposes an adaptive trajectory tracking control scheme for the load-carrying exoskeleton. The method is mainly composed of a computed torque controller and a fuzzy cerebellar model articulation controller. The fuzzy cerebellar model articulation controller is used to approximate model inaccuracies and load variations, and the computed torque controller deals with tracking errors. Simulations of an exoskeleton in squatting movements with model parameter changes and load variations are carried out, respectively. The results show a precise tracking response and high uncertainties toleration of the proposed method.

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“…However, if the active joint is directly driven by the gear pairs facilitates, although the transmission form and implementation is easy, the torque transmission for heavy loads requires large-diameter gears and high-power motors which should be avoided in compact structure design. In addition, the applied load torque increases with the joint angle when the joint bends in the stance phase [14]- [16]. Since the bevel gear transmission structure can only output a constant torque, resulting in poor torque availability and guarantee of torque demand at various positions during the motion trajectory.…”

Section: Introductionmentioning

confidence: 99%

A Novel Weight-Bearing Lower Limb Exoskeleton Based on Motion Intention Prediction and Locomotion State Identification

et al. 2019

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A variable magnification ratio transmission structure powered by the electric actuators is proposed to improve the flexibility and portability of the exoskeleton under heavy load carrying condition. The parameters of connecting rod size and hanging position are optimized to ensure that the output torque of active joints can fully envelope the demand load area. The control strategy based on intrinsic sensing is designed to realize the automatic human motion intention prediction and flexible trajectory tracking. The newly developed split embedded connecting rod can accurately measure the human-robot interaction (HRI) force applied to the exoskeleton and extract the human motion intention without being affected by the differences in wearing status. The force tracking control based on the zero-force following is modified by feedforward compensation with extreme learning machine (ELM), which enhances the response speed to human motion intention and reduces the HRI force by 70.6%. Based on multi-sensor information, stacked autoencoder deep neural networks (DNNs) are utilized to realize the automatic locomotion transition and the corresponding control parameters' switching. After optimization by a hybrid algorithm of genetic algorithm and particle swarm optimization (GA_PSO), the identification accuracy is enhanced from 96.2% to 99.7%. The adaptive neural-fuzzy inference system (ANFIS) is used to analyze the plantar pressure to achieve flexible switching between the swing phase and the stance phase. The experiments under various gait motion trajectories assisted by novel weight-bearing exoskeleton are carried out for evaluation, and the performance of the proposed control strategy based on motion intention prediction, locomotion mode identification, and gait phase switching is effectively verified.

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Biomechanical modeling and load-carrying simulation of lower limb exoskeleton

Cited by 23 publications

References 14 publications

Biomechanical design of escalading lower limb exoskeleton with novel linkage joints

Biomechanical design of escalading lower limb exoskeleton with novel linkage joints

Fuzzy cerebellar model articulation controller-based adaptive tracking control for load-carrying exoskeleton

A Novel Weight-Bearing Lower Limb Exoskeleton Based on Motion Intention Prediction and Locomotion State Identification

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