2,959 Hits in 6.3 sec

Properties of Elasto-Hydrodynamic Oil Film in Meshing of Harmonic Drive Gears

Adam Kalina, Aleksander Mazurkow, Waldemar Witkowski, Bartłomiej Wierzba, Mariusz Oleksy
2021 Materials  
Among the essential issues facing designers of strain wave gears, the provision for correct lubrication should be of paramount importance.  ...  The paper also provides a review of information concerning the design and principle of operation of strain wave transmission.  ...  Plastic greases used for strain wave gears.  ... 
doi:10.3390/ma14051194 pmid:33802557 fatcat:zk75bobr6vawbntv3xgi76r2ci

Vibration Signal Analysis for the Lifetime-Prediction and Failure Detection of Future Turbofan Components

N. Mokhtari, M. Grzeszkowski, C. Guhmann
2017 Technische Mechanik  
Tooth flank damage of a planet gear in a planetary gearbox design is investigated. High demands are placed on the signal processing due to design-related amplitude modulation effects.  ...  A separated analysis of each planet and evaluation of the envelope spectrum finally allows the detection of this failure type. Instead of roller bearings, HJB can be integrated in planet gears.  ...  Because the load and the viscosity were held constant, there is only a speed dependency. In the area with low speed and high AE RMS value solid friction occurs.  ... 
doi:10.24352/ub.ovgu-2017-118 fatcat:yno4trdpdbgl7h347irkdq3yny

Study on Lubrication Characteristics of Novel Forced Wave Generator of Harmonic Drive without Flexible Bearing

Hongli Jia, Hongbing Xin
2021 Materials  
speed.  ...  Further, the computational fluid dynamics (CFD) method is employed to study the effect of some factors on the lubrication characteristics of the ESB model including elliptical gap ratio, width, and rotational  ...  For HD, the stress in the FS depends on the load transmitted by the transmission, as well as the size of the meshing area and the distribution of loads in the meshing area.  ... 
doi:10.3390/ma15010215 pmid:35009360 pmcid:PMC8746004 fatcat:figtrzygczcirgkunn3stlj2wm

Compact Gearboxes for Modern Robotics: A Review

Pablo López García, Stein Crispel, Elias Saerens, Tom Verstraten, Dirk Lefeber
2020 Frontiers in Robotics and AI  
In most industrial robots, two relatively unconventional transmission technologies-Harmonic Drives© and Cycloid Drives-are usually found, which are not so broadly used in other industries.  ...  In this paper we propose an assessment framework strongly conditioned by HRI applications, and we use it to review the performance of conventional and emerging robotic gearbox technologies, for which the  ...  ., Stam s.r.l. and Wittenstein Galaxy GmbH for the kind support and explanations received, and for giving us permission to use the included images of their devices.  ... 
doi:10.3389/frobt.2020.00103 pmid:33501270 pmcid:PMC7806062 fatcat:m5jskuaaavb7tfbkfx753tmn7m

Motor Modeling and Optimization of a Back Actuated Lower Extremity Exoskeleton for Stair Gait Cycles

Amir Jafari
2017 International Robotics & Automation Journal  
Joint torque and power requirements of the unencumbered subject were scaled to include the effects of the extra mass and the position of the mass.  ...  Overall it was found that the selected power train could provide assistance positive assistance to the operator under these loading conditions.  ...  Strain wave gear units have several positive attributes such as the ability to fit extremely high reductions in small spaces.  ... 
doi:10.15406/iratj.2017.02.00031 fatcat:4uiy3ie7a5eohjqfmo5tb6v4ee

Multiscale modeling and simulation of rolling contact fatigue

Mir Ali Ghaffari, Yan Zhang, Shaoping Xiao
2018 International Journal of Fatigue  
In addition, the effects of temperature and nano-particles (debris) on the friction forces were discussed.  ...  In addition, the effects of temperature and nano-particles (debris) on the friction forces were discussed.  ...  The intention to study the fatigue of mechanical systems under random loads was raised from considering the effects of wind speed and direction on bearings and gear-teeth in wind turbine gearboxes.  ... 
doi:10.1016/j.ijfatigue.2017.11.005 fatcat:2booynju6vgcpi2fdqm44y3z7y

Experiments on the pressure distribution and frictional torque in articulating pin joints

J Zhu, S Pugh, R S Dwyer-Joyce, A Beke, G Cumner, T Ellaway
2010 Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology  
Friction coefficients in the range 0.08 to 0.11 were deduced in this way and were found to increase slightly with load.  ...  An estimate of the friction coefficient between pin and bush can be obtained directly from this lateral load and torque data.  ...  Acknowledgement The authors are grateful for the help and support of Safran Group and Messier-Dowty Ltd for their permission to publish this research.  ... 
doi:10.1243/13506501jet767 fatcat:exf4hrb2fzdl3crklq4gge2era

Model and experiments to determine lubricant film formation and frictional torque in aircraft landing gear pin joints

J Zhu, S Pugh, RS Dwyer-Joyce
2012 Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology  
In this paper, a mixed lubrication model of a grease lubricated landing gear joint is established to determine a theoretical Stribeck curve, frictional torque and lubricant film thickness under different  ...  The model can also predict the proportion of the load that is supported by contacting asperities and lubricant film.  ...  Acknowledgement The authors acknowledge the help and support of the Safran Group and Messier-Dowty Ltd and are grateful for their permission to publish.  ... 
doi:10.1177/1350650111434247 fatcat:ksk2mhte2res3fnmbfskz52rgu

Reliability Evaluation of Drivetrains: Challenges for Off‐ Highway Machines [chapter]

Lothar Wöll, Katharina Schick, Georg Jacobs, Achim Kramer, Stephan Neumann
2017 System Reliability  
The challenges, in determining both load cycles for the entire system and local component loads, are discussed in this work, along with approaches to face them.  ...  Since life expectancy of systems and its components strongly depends on the experienced load history, this information needs to be available as accurately as possible to allow reliable lifetime calculation  ...  For many applications, such as gears and bearings, the combination of speed and torque determines the strain on the component.  ... 
doi:10.5772/intechopen.70280 fatcat:6s4fwaweyba5xcvdxef4kjh66y

Passivity Guaranteed Dynamic Friction Model With Temperature and Load Correction: Modeling and Compensation for Collaborative Industrial Robot

Meseret Abayebas Tadese, Francisco Yumbla, June-Sup Yi, Woongyong Lee, Jonghoon Park, Hyungpil Moon
2021 IEEE Access  
In general, load-dependent friction is assumed to vary among the fourquadrant operation depending on the sign of load torque and speed.  ...  The robot has an integrated joint containing a direct drive frameless motor, strain wave gear set, a high-resolution encoder, brake, and integrated motor control electronics, including a temperature sensor  ...  For more information, see This article has been accepted for publication in a future issue of this journal, but has not been fully edited.  ... 
doi:10.1109/access.2021.3076308 fatcat:sym3lazb6bg5hjowjx56ftkxba


Anand Mohan Singh, Megha Bhawsar, Neeraj Kumar Nagayach
In this present work a virtual environment has been created to investigate the failure analysis on spur gear assembly in which structural analysis, fatigue failure analysis and contact stress analysis  ...  analysis, Augmented Lagrange method is set for contact analysis, for fatigue life analysis the fatigue strength factor is used as 0.85 for fully reverse loading and the life of shear stress in cycles  ...  Today, precision maneuverability means that it can also be used in positioning devices such as antenna readers. [45] Figure 6 . You can work at high speed and high loads.  ... 
doi:10.24113/ijoscience.v4i4.133 fatcat:ibp3u7zq4jf3hfio6blnw7zide

Analysis of slip-weakening frictional laws with static restrengthening and their implications on the scaling, asymmetry, and mode of dynamic rupture on homogeneous and bimaterial interfaces

L. M. Olsen-Kettle, D. Weatherley, E. Saez, L. Gross, H.-B. Mühlhaus, H. L. Xing
2008 Journal of Geophysical Research  
We employ various slip-weakening frictional laws to examine their effect on the resulting earthquake rupture speed, size and mode.  ...  We demonstrate the applicability of our elastoplastic fault model for modeling dynamic rupture and wave propagation in fault systems, and the rich array of dynamic properties produced by our elastoplastic  ...  In this model the compressional wave speed is V p = 6 km/s and the shear wave speed is Vs = 3.46 km/s.  ... 
doi:10.1029/2007jb005454 fatcat:ymueevevpnghxmgp5uki7evv3a

Torque ripple and misalignment torque compensation for the built-in torque sensor of harmonic drive systems

H.D. Taghirad, P.R. Belanger
1998 IEEE Transactions on Instrumentation and Measurement  
The method proposed by Hashimoto, in which strain gauges are directly mounted on the flexspline, is employed and improved in this paper.  ...  To minimize sensing inaccuracy, four Rosette strain gauges are used employing an accurate positioning method.  ...  Although only two Rosette strain gauges are sufficient to extract the torsional strain, two other Rosette strain gauges are introduced to maintain symmetry and to minimize the effect of positioning error  ... 
doi:10.1109/19.728840 fatcat:6qdosya5kjf7vmynaehwexsxea

Smart material/actuator needs in extreme environments in space

Stewart Sherrit, William D. Armstrong
2005 Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics  
These devices must be lightweight, compact and operate effectively under extreme conditions.  ...  Future missions to the planets and moons in our Solar System may require new technology.  ...  Research reported in this manuscript was conducted at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under a contract with National Aeronautics and Space Administration (NASA)  ... 
doi:10.1117/12.606475 fatcat:a2bot7uolzalvd7xtxy2qjpsqq

Implementation, Identification and Control of an Efficient Electric Actuator for Humanoid Robots

Florent Forget, Kevin Giraud-Esclasse, Rodolphe Gelin, Nicolas Mansard, Olivier Stasse
2018 Proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics  
The results show that this type of actuation is very suitable for legged robots and is a good candidate to replace strain wave gears.  ...  In particular, it is desirable that the actuators are back-drivable, efficient (low friction) and compact.  ...  Implementation, Identification and Control of an Efficient Electric Actuator for Humanoid Robots 37  ... 
doi:10.5220/0006825500390048 dblp:conf/icinco/ForgetGGMS18 fatcat:4xyipbqrirgzjk3tvgygjahybm
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