Simulation of impedance control applied to lower limb exoskeletons: assessment of its effectiveness in assisting disabled people during gait swing phase

2021 ◽  
Author(s):  
Denis Mosconi ◽  
Adriano A. G. Siqueira
Keyword(s):  
Lower Limb ◽  
Impedance Control ◽  
Swing Phase ◽  
Disabled People

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.

Impedance Control Based Sliding Mode for Lower Limb Rehabilitation Robot

2014 ◽  
Vol 672-674 ◽  
pp. 1770-1773 ◽  
Author(s):  
Fu Cheng Cao ◽  
Li Min Du
Keyword(s):  
Dynamic Response ◽  
Sliding Mode Control ◽  
Lower Limb ◽  
Control Method ◽  
Sliding Mode ◽  
Impedance Control ◽  
Rehabilitation Robot ◽  
Active Rehabilitation ◽  
Limb Rehabilitation ◽  
Lower Limb Rehabilitation

Aimed at improving the dynamic response of the lower limb for patients, an impedance control method based on sliding mode was presented to implement an active rehabilitation. Impedance control can achieve a target-reaching training without the help of a therapist and sliding mode control has a robustness to system uncertainty and vary limb strength. Simulations demonstrate the efficacy of the proposed method for lower limb rehabilitation.

sEMG-based impedance control for lower-limb rehabilitation robot

2017 ◽  
Vol 11 (1) ◽  
pp. 97-108 ◽  
Author(s):  
Vahab Khoshdel ◽  
Alireza Akbarzadeh ◽  
Nadia Naghavi ◽  
Ali Sharifnezhad ◽  
Mahdi Souzanchi-Kashani
Keyword(s):  
Lower Limb ◽  
Impedance Control ◽  
Rehabilitation Robot ◽  
Limb Rehabilitation ◽  
Lower Limb Rehabilitation

The Muscle Myogram as a Control Signal for Use in Powered Limb Orthosis

2006 ◽  
Author(s):  
M. Antonelli ◽  
P. Beomonte Zobel ◽  
J. Giacomin
Keyword(s):  
Lower Limb ◽  
Assistive Device ◽  
Sitting Position ◽  
Test Bed ◽  
Disabled People ◽  
Test Protocol ◽  
Prosthetic Devices ◽  
Specific Device ◽  
Definition Of

The choice of the command technique to be used in orthotic and prosthetic devices is very critical for the acceptance and, finally, the success of the specific device. Many variables influence this choice: the general characteristics of the signal, the quality of the correlation between signal and specific actions of the user and the algorithm that is derived, the acceptance of the technique, as applied to the specific device, from the user, etc. Among the command techniques, MMG signal seems to be promising to command an assistive device. In this paper a test protocol for studying MMG signal, to investigate the prospective for its use as a command technique of a powered lower limb orthosis capable of raising elderly and disabled people from the sitting position, is proposed. The definition of the test protocol, including the description of the test bed and the sensors application, is presented. Finally, the experimental results are showed and discussed.

Design and fabrication of a lower limb exoskeleton to assist in stair ascending

2019 ◽  
Vol 46 (2) ◽  
pp. 290-299 ◽  
Author(s):  
Payman Joudzadeh ◽  
Alireza Hadi ◽  
Bahram Tarvirdizadeh ◽  
Danial Borooghani ◽  
Khalil Alipour
Keyword(s):  
Lower Limb ◽  
System Performance ◽  
Design Methodology ◽  
Stair Climbing ◽  
Robot Design ◽  
Disabled People ◽  
Content Type ◽  
Lower Limb Exoskeleton ◽  
Knee Braces ◽  
Novel Design

Purpose This paper aims to deal with the development of a novel lower limb exoskeleton to assist disabled people in stair ascending. Design/methodology/approach For this purpose, a novel design of a mixture of motors and cables has been proposed for users to wear them easily and show the application of the system in stair climbing. Findings One of the prominences of this study is the provided robot design where four joints are actuated with only two motors; each motor actuates either the knees or ankles. Another advantage of the designed system is that with motors placed in a backpack, the knee braces can be worn under clothes to be concealed. Finally, the system performance is evaluated using electromyography (EMG) signals showing 28 per cent reduction in energy consumption of related muscles. Originality/value This investigation deals with the development of a novel lower limb exoskeleton to assist disabled people in stair ascending.

Fault tolerant control based on backstepping nonsingular terminal integral sliding mode and impedance control for a lower limb exoskeleton

2021 ◽  
pp. 095440622110357
Author(s):  
Majied Mokhtari ◽  
Mostafa Taghizadeh ◽  
Pegah Ghaf Ghanbari
Keyword(s):  
Sliding Mode Control ◽  
Lower Limb ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Impedance Control ◽  
Fault Tolerant Control ◽  
Integral Type ◽  
Lower Limb Exoskeleton ◽  
Mode Control ◽  
Control Scheme

In this paper, an active fault-tolerant control scheme is proposed for a lower limb exoskeleton, based on hybrid backstepping nonsingular fast terminal integral type sliding mode control and impedance control. To increase the robustness of the sliding mode controller and to eliminate the chattering, a nonsingular fast terminal integral type sliding surface is used, which ensures finite time convergence and high tracking accuracy. The backstepping term of this controller guarantees global stability based on Lyapunov stability criterion, and the impedance control reduces the interaction forces between the user and the robot. This controller employs a third order super twisting sliding mode observer for detecting, isolating ad estimating sensor and actuator faults. Motion stability based on zero moment point criterion is achieved by trajectory planning of waist joint. Furthermore, the highest level of stability, minimum error in tracking the desired joint trajectories, minimum interaction force between the user and the robot, and maximum system capability to handle the effect of faults are realized by optimizing the parameters of the desired trajectories, the controller and the observer, using harmony search algorithm. Simulation results for the proposed controller are compared with the results obtained from adaptive nonsingular fast terminal integral type sliding mode control, as well as conventional sliding mode control, which confirm the outperformance of the proposed control scheme.

Investigating the Effect of Real-Time Center of Pressure (CoP) Feedback Training on the Swing Phase of Lower Limb Kinematics in Transfemoral Prostheses with SACH foot

2021 ◽  
Author(s):  
Ashutosh Tiwari ◽  
Abhijeet Kujur ◽  
Jyoti Kumar ◽  
Deepak Joshi
Keyword(s):  
Real Time ◽  
Lower Limb ◽  
Knee Flexion ◽  
Center Of Pressure ◽  
Feedback System ◽  
Swing Phase ◽  
Flexion Angle ◽  
Heel Strike ◽  
Knee Flexion Angle ◽  
Joint Angles

Abstract Transfemoral amputee often encounters reduced toe clearance resulting in trip-related falls. Swing phase joint angles have been shown to influence the toe clearance therefore, training intervention that targets shaping the swing phase joint angles can potentially enhance toe clearance. The focus of this study was to investigate the effect of the shift in the location of the center of pressure (CoP) during heel strike on modulation of the swing phase joint angles in able-bodied participants (n=6) and transfemoral amputees (n=3). We first developed a real-time CoP-based visual feedback system such that participants could shift the CoP during treadmill walking. Next, the kinematic data were collected during two different walking sessions- baseline (without feedback) and feedback (shifting the CoP anteriorly/posteriorly at heel strike to match the target CoP location). Primary swing phase joint angle adaptations were observed with feedback such that during the mid-swing phase, posterior CoP shift feedback significantly increases (p<0.05) the average hip and knee flexion angle by 11.55 degrees and 11.86 degrees respectively in amputees, whereas a significant increase (p<0.05) in ankle dorsiflexion, hip and knee flexion angle by 3.60 degrees, 3.22 degrees, and 1.27 degrees respectively compared to baseline was observed in able-bodied participants. Moreover, an opposite kinematic adaptation was seen during anterior CoP shift feedback. Overall, results confirm a direct correlation between the CoP shift and the modulation in the swing phase lower limb joint angles.

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