scholarly journals Biped Gait Generation and Control Based on Mechanical Energy Constraint

10.5772/4861 ◽  
2007 ◽  
Author(s):  
Fumihiko Asano ◽  
Masaki Yamakita ◽  
Norihiro Kamamichi ◽  
Zhi-Wei Luo
Keyword(s):  
Mechanical Energy ◽  
Gait Generation ◽  
Energy Constraint ◽  
And Control

scholarly journals Dynamic Gait Generation and Control based on Mechanical Energy Restoration

2005 ◽  
Vol 23 (7) ◽  
pp. 821-830 ◽  
Author(s):  
Fumihiko Asano ◽  
Zhi-Wei Luo ◽  
Masaki Yamakita
Keyword(s):  
Mechanical Energy ◽  
Gait Generation ◽  
And Control ◽  
Dynamic Gait

Design of Powered Ankle-Foot Prosthesis With Nonlinear Parallel Spring Mechanism

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Fei Gao ◽  
Yannan Liu ◽  
Wei-Hsin Liao
Keyword(s):  
Energy Consumption ◽  
Design Method ◽  
Mechanical Energy ◽  
Power Requirement ◽  
Human Ankle ◽  
Cam Profile ◽  
Quadratic Bézier Curve ◽  
Spring Mechanism ◽  
Power And Energy ◽  
And Control

In this paper, a powered ankle-foot prosthesis with nonlinear parallel spring mechanism is developed. The parallel spring mechanism is used for reducing the energy consumption and power requirement of the motor, at the same time simplifying control of the prosthesis. To achieve that goal, the parallel spring mechanism is implemented as a compact cam-spring mechanism that is designed to imitate human ankle dorsiflexion stiffness. The parallel spring mechanism can store the negative mechanical energy in controlled dorsiflexion (CD) phase and release it to assist the motor in propelling a human body forward in a push-off phase (PP). Consequently, the energy consumption and power requirements of the motor are both decreased. To obtain this desired behavior, a new design method is proposed for generating the cam profile. Unlike the existing design methods, the friction force is considered here. The cam profile is decomposed into several segments, and each segment is fitted by a quadratic Bezier curve. Experimental results show that the cam-spring mechanism can mimic the desired torque characteristics in the CD phase (a loading process) more precisely. Finally, the developed prosthesis is tested on a unilateral below-knee amputee. Results indicate that, with the assistance of the parallel spring mechanism, the motor is powered off and control is not needed in the CD phase. In addition, the peak power and energy consumption of the motor are decreased by approximately 37.5% and 34.6%, respectively.

scholarly journals Spring-like leg behaviour, musculoskeletal mechanics and control in maximum and submaximum height human hopping

2011 ◽  
Vol 366 (1570) ◽  
pp. 1516-1529 ◽  
Author(s):  
Maarten F. Bobbert ◽  
L. J. Richard Casius
Keyword(s):  
Energy Expenditure ◽  
Muscle Activation ◽  
Mechanical Energy ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Centre Of Mass ◽  
Leg Stiffness ◽  
Reaction Forces ◽  
And Control ◽  
The Relationship

The purpose of this study was to understand how humans regulate their ‘leg stiffness’ in hopping, and to determine whether this regulation is intended to minimize energy expenditure. ‘Leg stiffness’ is the slope of the relationship between ground reaction force and displacement of the centre of mass (CM). Variations in leg stiffness were achieved in six subjects by having them hop at maximum and submaximum heights at a frequency of 1.7 Hz. Kinematics, ground reaction forces and electromyograms were measured. Leg stiffness decreased with hopping height, from 350 N m −1 kg −1 at 26 cm to 150 N m −1 kg −1 at 14 cm. Subjects reduced hopping height primarily by reducing the amplitude of muscle activation. Experimental results were reproduced with a model of the musculoskeletal system comprising four body segments and nine Hill-type muscles, with muscle stimulation STIM( t ) as only input. Correspondence between simulated hops and experimental hops was poor when STIM( t ) was optimized to minimize mechanical energy expenditure, but good when an objective function was used that penalized jerk of CM motion, suggesting that hopping subjects are not minimizing energy expenditure. Instead, we speculated, subjects are using a simple control strategy that results in smooth movements and a decrease in leg stiffness with hopping height.

scholarly journals The Mechanical Roles of Chaperones

2020 ◽  
Author(s):  
Deep Chaudhuri ◽  
Souradeep Banerjee ◽  
Soham Chakraborty ◽  
Shubhasis Halder
Keyword(s):  
Mechanical Energy ◽  
Protein Translation ◽  
Magnetic Tweezers ◽  
Trigger Factor ◽  
Biological Processes ◽  
Cellular Processes ◽  
Unfolded State ◽  
Cellular Energetics ◽  
Client Proteins ◽  
And Control

AbstractProtein folding under force is an integral source of generating mechanical energy in various cellular processes, ranging from protein translation to degradation. Although chaperones are well known to interact with proteins under mechanical force, how they respond to force and control cellular energetics remains unknown.To address this question, we introduce novel real-time microfluidics-magnetic-tweezers technology to apply physiological force pulses on client proteins, keeping the chaperones unperturbed. Interestingly, we observe that chaperones behave differently under force than its previously known functions. For instance, tunnel associated chaperones (trigger factor and DsbA), otherwise working as holdase without force, assist folding under force. This process generates an additional mechanical energy up to ~59 zJ to facilitate translation or translocation. However, other cytoplasmic oxidoreductases (PDI, thioredoxin) or well-known foldase chaperone (DnaKJE) does not possess this mechanical folding ability. Notably, the transferring chaperones (DnaK, DnaJ, SecB), act as unfoldase and slow down folding process to prevent misfolding of the client proteins. This provides an emerging insight of mechanical roles of chaperones: they can generate or consume energy by shifting energy landscape of the client proteins towards folded or unfolded state; suggesting an evolutionary mechanism to minimize the energy consumption in various biological processes.

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