scholarly journals Design and Preliminary Results of a Reaction Force Series Elastic Actuator for Bionic Ankle Prostheses

Author(s):  
Matt Carney ◽  
Tony Shu ◽  
Roman Stolyarov ◽  
Jean-Francois Duval ◽  
Hugh Herr

The TF8 actuator is an untethered, lower-extremity powered-prostheses designed to replicate biological kinetic and kinematic function of ankles. An energy optimal hardware specification was found by kinematically clamping walking gait data to the dynamic model of a series elastic actuator (SEA). We searched for a minimal electrical energy configuration of motor, reduction ratio, and spring, subject to specified constraints and ultimately discretely available components. The outcome translated into a mechanical design that heavily weighted the importance of mechanical energy storage in springs. The resulting design is a moment-coupled cantilever-beam reaction-force SEA (RFSEA) that has a nominal torque rating of 85Nm, peak torque of 175Nm, 105 degree range of motion, and a hardware mass of 1.6kg.

2012 ◽  
Vol 245 ◽  
pp. 99-106 ◽  
Author(s):  
S.M. Mizanoor Rahman

This paper presents the analysis of electro-mechanical design, selection of materials and manufacturing techniques for physical construction, dynamics, control etc. of a novel variable impedance compact compliant series elastic actuator (SEA) for human-friendly robotics applications. The electro-mechanical design consists of a servomotor, a ball screw, a torsional spring connecting the servomotor and the ball screw via a pair of spur gear, and a set of translational springs connecting the ball screw nut to the output link. The translational springs have low stiffness and these are used to handle low force operations that reduce non-linear friction, output impedance, impact etc. The torsional spring is in the high speed range, has high effective stiffness and it enhances the system bandwidth for large force operations when the translational springs are fully compressed. Suitable materials and appropriate manufacturing techniques for the construction of the actuator are discussed. Kinematics and working principle of the actuator are analyzed. The actuator model is simulated on the physical implementation for dynamics and control for different conditions. Simulation results prove satisfactory performances of the design. Then, advantages of the design over its existing counterparts are discussed, and its potential applications and future extensions are mentioned.


Author(s):  
Tian-Bing Xu ◽  
Lei Zuo

Abstract A “33” mode (mechanical stress being in parallel to the electric dipole moment direction) piezoelectric lead zirconate titanate (PZT) multilayer stack-based piezoelectric flextensional energy harvester (PZT-Stacked-FEH) has been developed. Interdisciplinary approaches had been taken to increase the performance of the PZT-Stacked-FEH. First, an elastic flextensional frame for force amplification has been optimally designed to capture more mechanical energy with high energy transition efficiency into the PZT-Stacked-FEH. Second, a “33” mode piezoelectric PZT multilayer stack (PZT-Stack) was employed instead of “31” mode (stress being in perpendicular to the dipole moment direction) single layer piezoelectric component to increase mechanical to electrical energy conversion efficiency and to generate more electrical charges in order to improve energy storage efficiency. With these approaches, the PZT-Stacked-FEH demonstrates excellent performance: 1) a 19% of overall mechanical to electrical energy conversion efficiency was achieved, 2) 48.6 times more mechanical energy was transited into PZT-Stacked-FEH and 26.5 times more electrical power was generated than directly applying force to the PZT-stack, and 3) energy storage efficiency was significantly improved. In this paper, we are focusing on the investigations for the off-resonance mode performance of the PZT-Stacked-FEH through theoretical modeling, prototype development, and experimental studies. A prototype PZT-Stacked-FEH of weight 18 grams was able to generate 666 mW electrical power under 52 Nrms force at 250 Hz, which is much lower than the resonant frequency (936 Hz). At this condition, a 6,600 μF super-capacitor was charged from 0 to 7 V in 1.6 second, at an average rate of 100 mW. Furthermore, 70% of generated appear electrical powers were delivered to matched resistive loads in the investigated regime of frequencies. Finally, the experimental results matched well with theoretical predictions which verified the developed theoretical models.


Author(s):  
Akin Oguz Kapti ◽  
Ahmet Karaca

This study proposes a joint simulator to evaluate new prosthesis designs prior to patient trials to minimize the inconveniences encountered in prosthesis applications for amputees. Design and prototype manufacturing of a force-controlled series elastic actuator was realized. In addition, actively controlled trans-tibial and trans-femoral amputation prostheses were designed by utilizing this actuator. A pneumatic joint simulator consisting of a proportional air pressure valve was also designed and manufactured. The experimental results demonstrated that good position tracking performances and effective assistive forces under the simulated walking conditions were achieved. The developed systems have the potential to contribute to the improvement of inadequate features of passive prostheses and to the development of new assistive systems that better respond to the needs of people with orthopedic disabilities.


Author(s):  
Ana-Maria Nasture ◽  
Maria Simona Raboaca ◽  
Laurentiu Patularu ◽  
Ciprian Lupu

Energy storage is a vital component in the chain of production-distribution-consumption of energy, even more so if the energy comes from a source that is intermittent and/or is not controllable as is the case with for example solar energy and wind energy. For many people, the term energy storage is the storage of electricity in batteries, as it is the most commonly found way of storing energy. In addition to classic batteries, there are other energy storage alternatives from a primary source for later use. The most valuable forms of energy storage are the ones that can both take over and release the energy on demand, in the form of electricity, such that, in the end, the electrical energy is transformed into thermal or mechanical energy. In stationary applications, energy can be stored in various forms such as batteries, ultracapacitors, or tanks of hydrogen, water, and different types of materials. This chapter will evaluate each form of energy storage.


2019 ◽  
Vol 8 (02) ◽  
pp. 1-6
Author(s):  
Adhe Anggry ◽  
Yuli Dharta ◽  
Andri Wiguna ◽  
Armada Armada ◽  
Ririn Martasari

Recent days, more and more people are becoming interested in "free-energy". "Free-energy" means the energy sources used freely without to pay. The sources of "free-energy" are sunlight, rainfall, wind energy, wave power, and tidal power. There are other sources of power such as gravity, electrical charge in the atmosphere and ionosphere, and a mass. FESS (Flywheel Energy Storage System) is an attempt to store kinetic energy generated from the rotation flywheel in which the electrical power output from the generator as an input to the motor. Mass flywheel greatly affects the amount of power generated by a generator which will serve as a flywheel device or distributors of energy while at the induction generator to eventually convert mechanical energy into electrical energy and vice versa. In this system design becomes very important for the flywheel can store the kinetic energy. This research aims to design and build mechanisms as a means of comparison FESS flywheel effect of the geometry of the kinetic energy generated. The research method is done by making three different geometric design flywheels, and then analyzed with the help of FESS. From the experimental results, flywheel 1 with a ringtype web-concave generate kinetic energy of 312.30 J and specific energy of 31.23 J / kg, at the flywheel 2 which is type-straight arm kinetic energy gained by 316.73 J and energy specific of 31.67 J / kg and flywheel 3 with a ring-type web-straight kinetic energy obtained by 284.997 J and specific energy of 28.49 J / kg. From the research data we can conclude that each design geometry flywheel has a different contribution to the performance of energy storage.


2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Roberta Alò ◽  
Francesco Bottiglione ◽  
Giacomo Mantriota

The human knee absorbs more energy than it expends in level ground walking. For this reason it would be useful if the actuation system of a wearable robot for lower limbs was able to recover energy thus improving portability. Presently, we recognize three promising technologies with energy recovery capabilities already available in the literature: the Series Elastic Actuator (SEA), the Clutchable Series Elastic Actuator (C-SEA), and the flywheel Infinitely Variable Transmission (F-IVT) actuator. In this paper, a simulation model based comparison of the performance of these actuators is presented. The focus is on two performance indexes: the energy consumed by the electric motor per gait and the peak torque/power requested to the electric motor. Both quantities are related to the portability of the device: the former affects the size of the batteries for a given desired range; the latter affects the size and the weight of the electric motor. The results show that, besides some well-explained limitations of the presented methodology, the C-SEA is the most energy efficient whereas the F-IVT allows cutting down the motor torque/peak power strongly. The analysis also leads to defining how it is possible to improve the F-IVT to achieve a reduction of the energy consumption.


2016 ◽  
Vol 8 (4) ◽  
Author(s):  
Jonathan P. Cummings ◽  
Dirk Ruiken ◽  
Eric L. Wilkinson ◽  
Michael W. Lanighan ◽  
Roderic A. Grupen ◽  
...  

This paper presents the development of a compact, modular rotary series elastic actuator (SEA) design that can be customized to meet the requirements of a wide range of applications. The concept incorporates flat brushless motors and planetary gearheads instead of expensive harmonic drives and a flat torsional spring design to create a lightweight, low-volume, easily reconfigurable, and relatively high-performance modular SEA for use in active impedance controlled devices. The key innovations include a Hall effect sensor for direct spring displacement measurements that mitigate the negative impact of backlash on SEA control performance. Both torque and impedance controllers are developed and evaluated using a 1-degree-of-freedom (DoF) prototype of the proposed actuator package. The results demonstrate the performance of a stable first-order impedance controller tested over a range of target impedances. Finally, the flexibility of the modular SEA is demonstrated by configuring it for use in five different actuator specifications designed for use in the uBot-7 mobile manipulator requiring spring stiffnesses from 3 N · m/deg to 11.25 N · m/deg and peak torque outputs from 12 N · m to 45 N · m.


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