Implementation of Pneumatic Air Muscle for Actuating Knee Exoskeleton Using Four-Bar Linkage

2019 ◽  
Vol 2 (3) ◽  
pp. 157-163
Author(s):  
Eka Budiarto ◽  
Dimas Anindito Widjanarko ◽  
Lydia Kidarsa
Keyword(s):  
Muscle Contraction ◽  
Linear Actuator ◽  
The Real ◽  
Human Knee ◽  
Control Scheme ◽  
Electrical Motors ◽  
Air Muscle ◽  
Four Bar Linkage

The knee exoskeleton is a device that assists users with weak knees to walk. It consists of a mechanical construction put around the human knee which is equipped with an actuator for movement. One mechanism that can be used to mimic movement of the real knee is the four-bar linkage. This research explores the possibility of using pneumatic air muscles as actuators for a knee exoskeleton with four-bar linkage implementation. A pneumatic air muscle is a single-acting linear actuator that contracts when filled with pressurized air, mimicking muscle contraction. It is much lighter than electrical motors, but—according to characterization done in this research—is difficult to control due to its inconsistent torque output. Nevertheless, this research shows that simple gait movements can be simulated using a knee exoskeleton actuated by pneumatic air muscles with an on-off control scheme. 

scholarly journals Development of a hinge compatible with the kinematics of the knee joint

2007 ◽  
Vol 31 (4) ◽  
pp. 371-383 ◽  
Author(s):  
José María Baydal Bertomeu ◽  
Juan Manuel Belda Lois ◽  
Ricard Barberà Guillem ◽  
Álvaro Page Del Pozo ◽  
Javiersanchez Lacuesta ◽  
...  
Keyword(s):  
Knee Joint ◽  
Lower Limb ◽  
Measurement Techniques ◽  
Knee Kinematics ◽  
Biomechanical Model ◽  
Human Movement ◽  
Helical Axis ◽  
Linkage Mechanism ◽  
Human Knee ◽  
Four Bar Linkage

This study aims to present a new concept of a knee hinge based on a crossed four-bar linkage mechanism which has been designed to optimally follow a motion curve representing the knee kinematics in the position at which the knee hinge should be placed. The methodology used to determine the optimal knee hinge is based on the optimization of certain variables of the crossed four-bar mechanism using genetic algorithms in order to follow a certain motion curve, which was determined using a biomechanical model of the knee motion. Two current, commercially available knee hinges have been used to theoretically determine their motion by means of the path performed by their instantaneous helical axis. Comparison between these two different knee hinges, Optimal Knee Hinge and the theoretical motion performed by a human knee reveals that a common monocentric hinge has a maximum misalignment of up to 27.2 mm; a polycentric hinge has a maximum misalignment of 23.9 mm. In contrast, the maximum misalignment produced by the Optimal Knee Hinge is 1.99 mm. The orthotic joint presented significantly improves the kinematical compatibility and the adjustment between orthotic and human joint motion, and should provide several advantages in terms of comfort and safety. Furthermore, the determination of the instantaneous helical axis for a particular user, by means of human movement measurement techniques, will enable the optimal crossed four-bar mechanisms to be determined in a customized and personalized manner. As a consequence, this new concept of orthotic knee joint design may improve the adaptability of lower limb orthoses for the user, and may lead to significant advantages in the field of orthotics for the lower limb.

Buoyancy Control for Low-Speed Under-Actuated AUVs

2014 ◽  
Vol 644-650 ◽  
pp. 735-740
Author(s):  
Yu Ling Ye
Keyword(s):  
Real Time ◽  
Control Algorithm ◽  
Sea Water ◽  
Water Tank ◽  
Low Speed ◽  
The Real ◽  
Control Approach ◽  
Control Scheme ◽  
Control Devices ◽  
Buoyancy Control

An engineering buoyancy control scheme was proposed to compensate the change of residual buoyancy for low-speed under-actuated AUVs. The buoyancy control system is made up of buoyancy controller and two sets of buoyancy control devices include: water tank, sea water pump, valve grouping, pipeline etc. Buoyancy control devices were configured to both head and tail part of the AUV symmetrical to its buoyant center. Depth control algorithm and buoyancy control algorithm were proposed separately. In the process of voyage at a constant depth, the real time speed, pitch angle and depth error were detected to evaluate the residual buoyancy indirectly, and then the real time buoyancy control was executed by pumping the water into or out of the tanks. The buoyancy control scheme was applied to the type of low-speed under-actuated AUV and simulation and experiments results show that the buoyancy control approach and the control laws are feasible and effective.

scholarly journals On singularities of real algebraic sets and applications to kinematics

2020 ◽  
Vol 18 (1) ◽  
pp. 1788-1813
Author(s):  
Marc Diesse
Keyword(s):  
Algebraic Variety ◽  
Configuration Spaces ◽  
The Real ◽  
Algebraic Sets ◽  
Delta Robot ◽  
Four Bar Linkage

Abstract We address the question of identifying non-smooth points in V ℝ ( I ) {{\bf{V}}}_{{\mathbb{R}}}(I) the real part of an affine algebraic variety. Two simple algebraic criteria will be formulated and proven. As an application, we investigate the configuration spaces of the planar four-bar linkage and the delta robot and prove that all singularities are CS-singularities.

scholarly journals Optimization of 3D controlled ELM-free state with recovered global confinement for tokamak fusion plasmas

2021 ◽  
Author(s):  
SangKyeun Kim ◽  
Ricardo Shousha ◽  
SangHee Hahn ◽  
Andrew Nelson ◽  
Josiah Wai ◽  
...  
Keyword(s):  
Real Time ◽  
Free State ◽  
Fusion Reactors ◽  
Fusion Plasmas ◽  
Real Time Control ◽  
The Real ◽  
Time Control ◽  
Control Scheme ◽  
Edge Localized Modes ◽  
Viable Approach

Abstract Mitigation of deleterious heat flux from edge-localized modes (ELMs) on fusion reactors is often attempted with 3D perturbations of the confining magnetic fields. However, the established technique of resonant magnetic perturbations (RMPs) also degrades plasma performance, complicating implementation on future fusion reactors. In this paper, we introduce an adaptive real-time control scheme as a viable approach to simultaneously achieve both ELM-free states and recovered high-confinement (βN~1.91$ and HN~0.9), demonstrating successful handling of a volatile complex system through adaptive measures. We show that, by exploiting a salient hysteresis process to adaptively minimize the RMP strength, stable ELM suppression can be achieved while actively encouraging confinement recovery. This is made possible by a self-organized transport response in the plasma edge which reinforces the confinement improvement through a widening of the ion pedestal and promotes control stability, in contrast to the deteriorating effect on performance observed in standard RMP experiments. These results establish the real-time approach as an up-and-coming solution towards an optimized ELM-free state, which is an important step for the operation of ITER and reactor-grade tokamak plasmas. Notably, the real-time adaptive control scheme introduced here provides a path towards economic fusion reactors by maximizing the fusion gain while minimizing damage to machine components.

Research on Design and Simulation of Four-Bar Linkage Mechanism of Hydraulic Support Based on Virtual Prototype Technology

2012 ◽  
Vol 170-173 ◽  
pp. 3539-3542 ◽  
Author(s):  
Yue Kan Zhang ◽  
Lin Jing Xiao
Keyword(s):  
Simulation Analysis ◽  
Graphical Method ◽  
Motion Path ◽  
Linkage Mechanism ◽  
Hydraulic Support ◽  
Work Requirements ◽  
3D Kinematics ◽  
The Real ◽  
Set Up ◽  
Four Bar Linkage

Four-bar linkage mechanism of the hydraulic support is designed by means of analytical and graphical method. A 3D kinematics model with Pro/E software is set up for the hydraulic support. The simulation analysis and interference of the hydraulic support is carried out and the motion path of the four-bar linkage mechanism under the real project condition is shown. The simulation result shows that the design of the four-bar linkage mechanism is reasonable and the designed hydraulic support meets its actual work requirements.

scholarly journals Design and Control of a New Biomimetic Transfemoral Knee Prosthesis Using an Echo-Control Scheme

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Mario G. Bernal-Torres ◽  
Hugo I. Medellín-Castillo ◽  
Juan C. Arellano-González
Keyword(s):  
Control Strategy ◽  
Knee Prosthesis ◽  
The Body ◽  
Metabolic Energy ◽  
Knee Prostheses ◽  
Human Knee ◽  
Knee Movement ◽  
Control Scheme ◽  
Sound Side ◽  
And Control

Passive knee prostheses require a significant amount of additional metabolic energy to carry out a gait cycle, therefore affecting the natural human walk performance. Current active knee prostheses are still limited because they do not reply with accuracy of the natural human knee movement, and the time response is relatively large. This paper presents the design and control of a new biomimetic-controlled transfemoral knee prosthesis based on a polycentric-type mechanism. The aim was to develop a knee prosthesis able to provide additional power and to mimic with accuracy of the natural human knee movement using a stable control strategy. The design of the knee mechanism was obtained from the body-guidance kinematics synthesis based on real human walking patterns obtained from computer vision and 3D reconstruction. A biomechanical evaluation of the synthesized prosthesis was then carried out. For the activation and control of the prosthesis, an echo-control strategy was proposed and developed. In this echo-control strategy, the sound side leg is sensed and synchronized with the activation of the knee prosthesis. An experimental prototype was built and evaluated in a test rig. The results revealed that the prosthetic knee is able to mimic the biomechanics of the human knee.

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