A Control Strategy for a Lower Limb Exoskeleton with a Toe Joint

2016 ◽  
pp. 1-8 ◽  
Author(s):  
Sergey Jatsun ◽  
Sergei Savin ◽  
Andrey Yatsun
Keyword(s):  
Control Strategy ◽  
Lower Limb ◽  
Lower Limb Exoskeleton

Dynamic trajectory adjustment of lower limb exoskeleton in swing phase based on impedance control strategy

2020 ◽  
Vol 234 (10) ◽  
pp. 1120-1132
Author(s):  
Lingling Chen ◽  
Chao Wang ◽  
Xiaowei Song ◽  
Jie Wang ◽  
Tengyu Zhang ◽  
...  
Keyword(s):  
Contact Force ◽  
Control Strategy ◽  
Lower Limb ◽  
Impedance Control ◽  
Swing Phase ◽  
Motion Trajectory ◽  
Movement Trajectory ◽  
The Road ◽  
Lower Limb Exoskeleton ◽  
Coupling Characteristics

The lower limb exoskeleton provides assistance by following the lower limb joints’ desired motion trajectory. However, angle control is not enough to meet the requirements in some special circumstances such as encountering obstacles. In the swing phase of the attached leg with the exoskeleton, there is a different contact force between the sole and the road surface in different road conditions. Therefore, it is particularly important to control the joint angle and contact force simultaneously, that is, it is not only necessary to follow the desired angle but also to minimize the influence of external contact force. In this article, a novel scheme is proposed to adjust the trajectory dynamically in the swing phase. First of all, the physical model is streamlined and the Lagrangian principle is carried out to dynamic analysis and established a model of lower limb exoskeleton in the swing phase. Furthermore, the angle dynamics equation is transformed into a Cartesian coordinate system to calculate the end contact force for the impedance model. Finally, the impedance control strategy together with a disturbance observer is designed which is suitable for nonlinear and strong coupling characteristics. The simulation result shows that the control system can follow the angle accurately in the condition of minimizing external constraints. Hardware experiment shows that lower extremity exoskeleton can adjust motion trajectory actively when encountering obstacles and complete the movement trajectory tracking at the same time.

scholarly journals Command Filter Backstepping Sliding Model Control for Lower-Limb Exoskeleton

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Peng Yang ◽  
Gaowei Zhang ◽  
Jie Wang ◽  
Xiaozhou Wang ◽  
Lili Zhang ◽  
...  
Keyword(s):  
Control Strategy ◽  
Lower Limb ◽  
Sliding Mode ◽  
Lyapunov Theory ◽  
Reference Trajectory ◽  
Fuzzy Logic Systems ◽  
Lower Limb Exoskeleton ◽  
Model Control ◽  
Command Filter ◽  
The Stability

A command filter adaptive fuzzy backstepping control strategy is proposed for lower-limb assisting exoskeleton. Firstly, the human-robot model is established by taking the human body as a passive part, and a coupling torque is introduced to describe the interaction between the exoskeleton and human leg. Then, Vicon motion capture system is employed to obtain the reference trajectory. For the purpose of obviating the “explosion of complexity” in conventional backstepping, a second-order command filter is introduced into the sliding mode control strategy. The fuzzy logic systems (FLSs) are also applied to handle with the chattering problem by estimating the uncertainties and disturbances. Furthermore, the stability of the closed-loop system is proved based on the Lyapunov theory. Finally, simulation results are presented to illustrate the effectiveness of the control strategy.

Analyzing Motor Primitives of Healthy Subjects Wearing a Lower Limb Exoskeleton

2017 ◽  
Author(s):  
Wilian dos Santos ◽  
Samuel Lourenco ◽  
Adriano Siqueira ◽  
Polyana Ferreira Nunes
Keyword(s):  
Lower Limb ◽  
Healthy Subjects ◽  
Motor Primitives ◽  
Lower Limb Exoskeleton

Impedance-based Backdrivability Recovery of a Lower-limb Exoskeleton for Knee Rehabilitation

2019 ◽  
Author(s):  
Miguel D. Sanchez Manchola ◽  
Luis J. Arciniegas Mayag ◽  
Marcela Munera ◽  
Carlos A. Cifuentes Garcia
Keyword(s):  
Lower Limb ◽  
Lower Limb Exoskeleton ◽  
Knee Rehabilitation
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