scholarly journals Design and Control of an Adaptive Knee Joint Exoskeleton Mechanism with Buffering Function

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8390
Author(s):  
Yapeng Wang ◽  
Wei Zhang ◽  
Di Shi ◽  
Yunhai Geng
Keyword(s):  
Knee Joint ◽  
Tracking Error ◽  
Adaptive Controller ◽  
Average Force ◽  
Human Knee ◽  
Rotation Center ◽  
Structure And Motion ◽  
System A ◽  
Motion Characteristics ◽  
And Control

A knee exoskeleton with an adaptive instantaneous rotation center and impact absorption is used for rehabilitation. Due to the human knee joint’s special physiological structure and motion characteristics, the exoskeleton mechanism needs to be designed for both static and dynamic aspects. Therefore, a novel knee exoskeleton mechanism was designed. To adapt to the rotation center of the knee joint, a mechanism with cross-configuration was designed according to the equivalent degree of freedom and the stiffness of the springs was calculated by its combination with gait motion, so that the average force of the human body was minimized. A dynamic model of the exoskeleton was established. To overcome the uncertainty in the parameters of the human and robotic limbs, an adaptive controller was designed and a Lyapunov stability analysis was conducted to verify the system. A simulation was conducted and experimental results show that the tracking error of the knee joint angle between the actual and desired trajectory was within the range of −1 to 1 degree and indicate the effectiveness of the controller.

Cadaveric Evaluation of Soft-Tissue Constraint in the Human Knee

2013 ◽  
Author(s):  
Adam Cyr ◽  
Lorin Maletsky
Keyword(s):  
Soft Tissue ◽  
Knee Joint ◽  
Joint Kinematics ◽  
Motion Patterns ◽  
Passive Motion ◽  
Human Knee ◽  
Human Knee Joint ◽  
Knee Joint Kinematics ◽  
Motion Characteristics

The motion patterns of the human knee joint depend on its passive motion characteristics, which are described by the ligamentous and articular constraints. Since active motions, like walking and squatting are believe to fall within a passive envelope, the basis for the understanding of the knee joint kinematics lies in the description of its passive characteristics.

The reproducibility of passive human knee-joint motion characteristics

1985 ◽  
Vol 18 (7) ◽  
pp. 529-530
Author(s):  
L. Blankevoort ◽  
R. Huiskes ◽  
A. de Lange
Keyword(s):  
Knee Joint ◽  
Joint Motion ◽  
Human Knee ◽  
Human Knee Joint ◽  
Knee Joint Motion ◽  
Motion Characteristics

scholarly journals Ligament-Bone Interaction in a Three-Dimensional Model of the Knee

1991 ◽  
Vol 113 (3) ◽  
pp. 263-269 ◽  
Author(s):  
L. Blankevoort ◽  
R. Huiskes
Keyword(s):  
Knee Joint ◽  
Line Element ◽  
External Rotation ◽  
Contact Point ◽  
Three Dimensional ◽  
Considerable Effect ◽  
Joint Models ◽  
Three Dimensional Model ◽  
Human Knee ◽  
Motion Characteristics

In mathematical knee-joint models, the ligaments are usually represented by straightline elements, connecting the insertions of the femur and tibia. Such a model may not be valid if a ligament is bent in its course over bony surfaces, particularly not if the resulting redirection of the ligament force has a considerable effect on the laxity or motion characteristics of the knee-joint model. In the present study, a model for wrapping of a ligament around bone was incorporated in a three-dimensional mathematical model of the human knee. The bony edge was described by a curved line on which the contact point of the line element representing a ligament bundle was located. Frictionless contact between the ligament bundle and the bone was assumed. This model was applied to the medial collateral ligament (MCL) interacting with the bony edge of the tibia. It was found that, in comparison with the original model without bony interactions, the bony edge redirected the ligament force of the MCL in such a way that it counterbalanced valgus moments on the tibia more effectively. The effect of the bony interaction with the MCL on the internal-external rotation laxity, however, was negligible.

Output Synchronization for Teleoperation of Wheel Mobile Robot

2009 ◽  
Author(s):  
Patrick Miller ◽  
Leng-Feng Lee ◽  
Venkat Krovi
Keyword(s):  
Mobile Robot ◽  
Adaptive Controller ◽  
Robotic Systems ◽  
Lagrangian Systems ◽  
Slave System ◽  
Hardware In The Loop ◽  
System A ◽  
Output Synchronization ◽  
Stable Means ◽  
And Control

The potential for use of robotic systems in remote applications arenas has long motivated development of robust and stable means of teleoperated control of slave systems. However, telerobotic systems face challenges stemming from the devices themselves, environmental factors, communication and control complexities. To address these challenges, we will adopt the passivity based synchronization framework [1] and study its applicability to safely synchronize two heterogeneous Lagrangian systems. Within this framework, an adaptive controller identifies and stabilizes the dynamics of the master and slave systems and renders the dynamics passive to a secondary coupling input. The passive mapping used to couple the output states of the master and slave systems and is made insensitive to lossy and delayed communication medium. Specifically, an adaptive passive synchronization teleoperation controller is developed between an Omni haptic device that serves as our master and a differentially driven nonholonomic Wheel Mobile Robot (WMR) as the slave system. A battery of hardware-in-the-loop simulations are used to verify the proposed controller.

Modeling and Control of Electric Linear Actuator for Driving Knee Joint of a Lower Body Exoskeleton

2020 ◽  
pp. 50-67
Author(s):  
Ganesh Roy ◽  
Hano Jacob Saji ◽  
Subir Das ◽  
Subhasis Bhaumik
Keyword(s):  
Knee Joint ◽  
Sliding Mode ◽  
Ease Of Use ◽  
Control Action ◽  
Assistive Device ◽  
Linear Actuator ◽  
Modeling And Control ◽  
Human Knee ◽  
Engineering And Technology ◽  
And Control

The actuator is an integrated part of every robotic system which can actuate the joint for the necessary movement of the device. Depending on the energy conversion mechanism, the actuators are subdivided into three classes, namely electric, pneumatic, and hydraulic. The electric actuators are very popular in the field of engineering and technology due to their ease of use and low maintenance. In this chapter, an electric linear actuator (Manufactured by TiMOTION, Model: TA1) has been modeled by considering its each and every associated physical parameter and also simulated in MATLAB Simscape to observe its performance. Also, different control actions like PID, LQR, and Sliding mode methods have been studied to select the best control action for the actuator. Finally, as an application of the developed actuator model, a one DOF robotic assistive device called human knee exoskeleton has been designed in the MATLAB Simscape. It has been tested that the knee joint trajectory has been followed by the actuator with suitable control action.

scholarly journals Stability Analysis and Control of a New Smooth Chua's System

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Guopeng Zhou ◽  
Jinhua Huang ◽  
Xiaoxin Liao ◽  
Shijie Cheng
Keyword(s):  
Stability Analysis ◽  
Equilibrium Points ◽  
Adaptive Controller ◽  
Invariant Set ◽  
Estimation Errors ◽  
Linear Controller ◽  
System A ◽  
Chaotic Characteristic ◽  
The Stability ◽  
And Control

This paper is concerned with the stability analysis and control of a new smooth Chua's system. Firstly, the chaotic characteristic of the system is confirmed with the aid of the Lyapunov exponents. Secondly, it is proved that the system has globally exponential attractive set and positive invariant set. For the three unstable equilibrium points of the system, a linear controller is designed to globally exponentially stabilize the equilibrium points. Then, a linear controller and an adaptive controller are, respectively, proposed so that two similar types of smooth Chua's systems are globally synchronized, and the estimation errors of the uncertain parameters converge to zero asttends to infinity. Finally, the numerical simulations are also presented.

Evaluating Relationship Between Passive Knee Envelope and a Dynamically Simulated Walk

2010 ◽  
Author(s):  
Amit M. Mane ◽  
Lorin P. Maletsky
Keyword(s):  
Knee Joint ◽  
Principal Component ◽  
Motion Patterns ◽  
Human Knee ◽  
Human Knee Joint ◽  
Analysis Technique ◽  
Knee Joint Kinematics ◽  
Motion Characteristics ◽  
Muscle Activations ◽  
Tibiofemoral Kinematics

The motion patterns of the human knee joint depend on its passive motion characteristics, which are described by the ligamentious and articular constraints. Since active motions, like walking and squatting are believed to fall within a passive envelope, the basis for the understanding of the knee joint kinematics lies in the description of its passive constraint characteristics [1]. The link between the knee passive envelope and the kinematics during various dynamic activities has not been studied. It is unclear how the articular geometry and muscle activations of the knee influence the contribution of ligament constraints during dynamic activities. To explain the relationship between knee passive envelope and dynamic activities completely, new methodology must be developed. The objective of the present study was to estimate the effects of variation in passive knee envelope on the tibiofemoral kinematics during dynamically simulated gait using a multivariate analysis technique, principal component (PC) analysis.

Event Triggered Neuroadaptive Controller (ETNAC) Design for Uncertain Affine Nonlinear Systems

2018 ◽  
Author(s):  
A. Ghafoor ◽  
J. Yao ◽  
S. N. Balakrishnan ◽  
J. Sarangapani ◽  
T. Yucelen
Keyword(s):  
Nonlinear Systems ◽  
Controller Design ◽  
Tracking Error ◽  
Adaptive Controller ◽  
Fast Estimation ◽  
System A ◽  
High Frequency Oscillations ◽  
Feedback Network ◽  
Affine Nonlinear Systems ◽  
Event Triggered

In this paper, a novel event triggered neural network (NN) adaptive controller is presented for uncertain affine nonlinear systems. Controller design is based on an observer, called as Modified State Observer (MSO), which is used to approximate uncertainties online. State is sensed continuously yet sent on feedback network only when required, in aperiodic fashion. Lyapunov analysis is used to derive this condition which is dynamic in nature since it is based on tracking error. In this way ETNAC helps to not only saves communication cost but also computational efforts. MSO formulations have two tunable gains which let you do fast estimation without inducing high frequency oscillations in the system. A benchmark example of 2-link robotic manipulator is used to show the efficacy of the proposed controller.

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